PYSC 220 Exam 2
The receptive field of a typical bipolar and ganglion cell
Co-centric receptive field
Transduction
a process by which light is converted into electrical signals in the rod cells, cone cells and photosensitive ganglion cells of the retina of the eye; photoreceptors detect light then create a neural memo and sends it back to the rest of the brain
even long after the sensitive period
a prolonged experience of no visual stimulation produces a measurable effect on the visual cortex
Nerve Growth Factor (NGF)
a protein that promotes the survival and growth of the axon - neurotrophin
simple V1 neurons converge their data onto one complex V1 neuron to result in
a receptive field which is rectangular with no stat "on" or "off" region
several V1 complex cells converge their data onto one hypercomplex V1 neuron to result in
a receptive field which may respond movement as well as length of line
LGN neurons converge their data onto one V1 cortical simple cell to result in
a receptive fields which looks like a rectangle with a surround
negative color afterimage
a replacement of red with green, green with red, yellow and blue with each other, and black and white with each other
Foveal Vision Brightness sensitivity
Distinguishes among bright lights; responds poorly to dim light
chemoreceptors
a sensory receptor that transduces a chemical signal into an action potential. In more general terms, a chemosensor detects certain chemical stimuli in the environment
phantom pain elimination
using an artificial limb can make the brain attribute the sensations to the artificial limb, displacing the abnormal connections that causes phantom sensations
Brains of adults can reorganize with special training but...
usually not enough to show changes on an MRI
Koniocellular Neurons Respond to
varied
people's ability to recognize faces
varies because they don't care or don't pay attention
Problem with place theory
various parts of the basilar membrane are bound together too tightly to resonate like a piano string
to what is the organization of the auditory cortex similar?
very similar to the organization of the visual cortex → auditory cortex also has dorsal and ventral streams (and some of these areas overlap with the visual areas)
size of the vestibular system
very small in almost all creatures
vestibular pathway
vestibular hair cells sends info to → brainstem & cerebellum • (e.g., projections to brainstem = nausea/vomiting) • (cerebellum = balance)
monocular cues
• relative size height in plane • linear perspective • texture gradient • interposition • light and shadow
vestibular organ consists of
• saccule • utricle • three semicircular canals
primary tastes & molecules
• salty • sweet • bitter • sour • umami
C fibers and pain
• smaller diameter than A-δ fibers; unmyelinated, bit slower • dull, aching pain (tooth ache, post-operative pain)
properties of vision stimulus
• wavelength • Frequency • amplitude • purity
Surrounding the primary auditory cortex
additional auditory areas that respond best to auditory "objects" • i.e. animal cries, machinery noises, music, etc.
DNA contains four "bases"
adenine, guanine, cytosine, and thymine
neurons make...
adjustments to maintain a nearly constant level of arousal • learning arouses your brain so after learning strengthens one set of synapses, others weaken and vice versa
olfactory stimuli
airborne chemicals • odorants (volatile substances with molecular weights of 15 to 300 daltons)
olfaction processes...
airborne chemicals that do not range along a single continuum
damage to MT aka V5
akinetopsia/motion blindness
Why have pain?
alert us when something is wrong
amygdala and pain
fear emotions
glutamate and pain
feel a little pain
during reproduction
female gives an X and the male gives an X or a Y which determines the gender of the offspring - Exceptions are possible but uncommon
Sensitive period
a period of time when experiences have a particularly strong and enduring influence • ends with the onset of certain chemicals that stabilize synapses and inhibit axonal sprouting
spina bifida
a portion of the neural tube has failed to become submerged properly and has grown on the outside of the fetus - nervous tissue must be put back in but children will never be the same/have all control - FOLIC ACID
Most cells in the primary auditory cortex have...
a preferred tone
different parts of the brain's visual system get information on a
need-to-know basis
Information from the auditory system...
passes through subcortical areas, axons cross over in the midbrain to enable each hemisphere of the forebrain to get most of its information from the opposite ear
Color constancy
the ability to recognize colors despite changing light • not easily explained by the trichromatic or opponent process theory
Color constancy lost when
the ability to recognize something as being the same color despite changes in lighting • lost if V4 is damaged
Blindsight
the ability to respond in limited ways to visual information without perceiving it consciously (insist they are "just guessing"
Motion Blindness
the ability to see objects but impairment at seeing whether they are moving or, if so, which direction and how fast - caused by damage to MT and MST - severe impairment - Saccades
effects of a stroke: edema
the accumulation of fluid • Increases pressure on the brain and the probability of additional strokes
three semicircular canals for...
the three planes • saggital (nodding) • transverse (cartwheeling) • horizontal (turning head)
horizontal cells
type of cell that receives input from receptors and delivers inhibitory input to bipolar cells
primary olfactory cortex
uncus located in the temporal lobe
damaged axons grow back...
under certain circumstances
where do we have trouble localizing low and medium frequency sounds?
underwater
Genes
units of heredity that maintain their structural identity from one generation to another; part of a chromosome composed of the double stranded molecule deoxyribonucleic acid (DNA) • Come in pairs aligned along chromosomes
c fibers
unmyelinated nerves that slowly transmit pain signals • free nerve endings
taste transduction: umami
unsalted meat flavor, savory - receptor linked to transducin & gustducin (just know that the receptor is therefore metabotropic but you don't have to memorize "transducin" and "gustducin") - T1R1 + T1R3 - receptor can sense sweet or umami but not both • so again, taste depends on which receptors AS WELL AS the actual pattern of receptor firing
necrosis
unwanted death; bad rotting
humans can recognize
up to 10,000 odorants (though we are bad at labeling the odors specifically; usually just know we have smelled it before)
foliate papillae
up to 1300 taste buds
circumvallate papillae
up to 250 taste buds
fungiform papillae
up to 8 taste buds (you don't have to memorize this information—just know that there are different types of "bumps" and they are associated with different numbers of taste buds)
Current theory: frequencies higher than 4000 Hz
use a mechanism like place theory → the highest frequency sounds vibrate hair cells near from base where the basilar membrane is still and the lower frequency sounds vibrate hair cells farther along the membrane where is gets floppier
evolutionary psychology is
useful but must be tested to find out if it's true
Transcutaneous electrical nerve stimulation
uses low-voltage electrical current for pain relief • may be because the electricity from the electrodes stimulates the nerves in an affected area and sends signals to the brain that block or "scramble" normal pain signals • the electrical stimulation of the nerves may help the body to produce natural painkillers called endorphins, which may block the perception of pain
cell bodies of Parvocellular Neurons
Smaller
Color sensitivity of Koniocellular Neurons
Some are
sometimes genes...
Sometimes several genes overlap on a stretch of chromosome - Means genetic outcome depends on parts of two or more chromosomes • Part of a chromosome alters the expression of a gene without coding for any protein of its own
ventral MST
motion of objects relative to its background
in the PNS
motor and sensory axons grow back toward the periphery at about 1 mm per day
taste nerves project to the...
nucleus of the tractus solitarius (NTS
touch on the tongue processed by...
somatosensory cortex
Binocular input
stimulation from both eyes
taste results from...
stimulation of taste buds
sensation
stimuli and the receptors; the biology, physics, mechanics of it
Chromosomes
strands of genes that come in pairs • Male mammals → have an unpaired X and Y chromosome with different genes
NTS
structure in the medulla From here, info branches out reaching the pons, the lateral hypothalamus, the amygdala, the ventral-posterior thalamus, and two areas of the cerebral cortex: - Somatosensory cortex → touch on the tongue - Insula → primary taste cortex
stronger pain releases...
substance P and CGRP
sweet receptor stimuli
sugars, but also some amino acids
ferret study: damage to
superior colliculus (visual), occipital lobe (visual), inferior colliculus (auditory) (in one, e.g., left hemisphere) - destroyed target location for retinal nerves; kept auditory cortex intact
penumbra
surrounding area (also affected in a few days after stroke; may die or just not function normally)
olfactory receptors survive...
survive on average just over a month - at that point a stem cell makes a new olfactory cell in the same place that does the same thing • axon must connect to the same place
olfaction, emotions, and sweat
sweat from different emotions evokes different emotions in others
if experience is deprived from one eye in a young kitten
synapses in the visual cortex become unresponsive or go to the other eye and the deprived eye becomes unresponsive • less severe in older animals but still occurs
mcclintock effect
synchronization of menstrual cycles when females have a lot of contact with each other • Robust effect in humans
visible "light" for humans is between the range of
380 and 760 nanometers (billionths of a meter).
blueprint hypothesis
A growing axon follows a path of cell surface molecules attracted by some chemicals and repelled by others in a process that steers the axons in the correct direction Pioneer growth cones interact with NCAMS along the path to the target. Subsequent neurons follow this "blazed trail" (fasciculation)
estradiol and pain
facilitates opiate activity - women have a lot of estradiol when pregnant
unilateral deafferentiation of upper limb
numb limb, didn't like to use but actually could but only used normal arm
bilateral deafferentation of upper limbs
numb limbs, used both arms because they were both numb
Primate ganglion cells fall into 3 categories
parvocellular, magnocellular, and koniocellular
Neurogenesis/Proliferation
the production of new cells; very rapid - symmetrical and asymmetrical division
Free nerve ending
(unmyelinated or thinly myelinated axons) - located Near base of hairs and elsewhere in skin - responds to Pain, warmth, cold
Merkel's disks in men and women
Women have same number packed into smaller area than men so can detect smaller differences
Ewald Hering
19th century physiologist who proposed the opponent-process theory
adaptation of taste buds
(that is, a taste bud can quickly adapt to a particular taste); the fatigue of receptors sensitive to sour tastes • makes buffets dangerous because we quickly tire of one taste but not another and will move on to eating something else just for the new taste so we overeat
vestibular sacs: utricle
(tilting of head)
most receptors are
"mixed," "polymodal"
neural darwinism
"survival of the fittest" with neurons; neurons that are stronger/better are kept, weaker neurons are eliminated we start with more neurons and synapses than we can keep and then a selection process keeps some synapses and rejects other • the most successful axons and combos survive; others fail
current theory: for low frequency sounds
( up to 100 Hz) the basilar membrane vibrates in synchrony with the sound waves
outer hair cells
(12,000) - cause auditory acuity; if damaged can still hear just not as well
inner hair cells
(3,500) - very important; if damaged can't hear
Tympanic membrane
(aka eardrum) a membrane that vibrates at the same frequency as the sound waves that strike it • Connects to 3 tiny bones (Ossicles)
bitter receptor stimuli
(alkaloids, often poisonous)
syphilis
(bacteria)—Tuskegee tragedy • eat up neural tissue • penicillin found to cure syphilis but researchers did not share this with the black participants because they wanted to study the effects of syphilis
contusion
(bruise) • due to broken blood vessels • usually contrecoup injury → the injury is in the opposite side as where brain got hit, because brain bangs against opposite side of skull
90% of visual information goes through what pathway
(from retina, to LGN, to V1)
purity
(how complex is the waveform—that is, how many different types of sine waves make up this sound wave?) - timbre
amplitude
(how high/low peaks/troughs go) → brightness - stimuli of the same wavelength, but different amplitudes will look differently to us (aka brighter or dimmer)
purity
(how much of the same wavelength you're getting) → saturation - the more similar wavelengths are combined, the more vivid the picture looks to us - if you have many different wavelengths, it's going to look whitish like sunlight • additive color mixing • subtractive color mixing
belt region of the auditory cortex
(just surrounds the core region) first level of association cortex
Strabismus
(lazy eye) a condition in which the eyes do not point in the same direction • generally, children with this condition attend to one eye and not the other
The result of an experience...
(maternal deprivation, cocaine exposure, new learning, etc.) in some way alters the chemical environment within a cell
Evidence that plasticity occurs during the lifetime
(not just prenatally or several years after birth) • Enriched environment vs. impoverished environment vs. over-enriched environment
Frequency
(number of peaks/troughs) - Short wavelength = high frequency - Long wavelength = low frequency
wavelength
(peak to peak difference) → color/hue - R O Y G B I V (moving from long wavelength to short wavelengths)
Non-taster, taster, supertaster
- # of fungiform papillae near tip of tongue affect how well you taste - those who are more insensitive to taste have slightly more body weight
Pain perception pathway is different
- C fibers - A-δ fibers
Deafness
- Conductive deafness/Middle-ear deafness - Nerve deafness/Inner-ear deafness
Congenital insensitivity to pain with anhidrosis
- Defect from birth - Also associated with Anhidrosis → proplems with temperature control
sensations of the somatosensory system include
- Discriminative touch - Deep pressure - Cold/warmth - Pain vs. itch. Vs. tickle - Position and movement of joints
fetal alcohol syndrome damages the brain in several ways...
- Early stages → interferes with neuron proliferation - Little later → impairs neuron migration and differentiation - Still later → impairs synaptic transmission - Kills neurons by apoptosis by inhibiting glutamate (which upregulates glutamate receptors) and enhancing GABA receptors - As alcohol leaves, upregulated glutamate receptors are overexcited bringing in excess sodium and calcium which poisons the mitochondria resulting in cell death
Various experiences can ...
- Ex → offspring of malnourished rats are genetically predisposed to conserve energy so if rich food becomes available later in life, they're more likely to become obese - Ex → rats with little maternal care early in life have altered gene expression in the hippocampus leading to high vulnerability to emotional stress reactions later in life
Brain adaptations in people blind since infancy
- Fingers → more sensitive, especially in those who read Braille because they are used more • Touch and sound actually activates the occipital cortex in blind people which is usually devoted to vision alone - Lips → no more sensitive because they are not used more
somatosensory receptors
- Free nerve ending - Hair-follicle receptors - Meissner's corpuscles - Pacinian corpuscles - Merkel's disks - Ruffini endings - Krause end bulbs
chemical coding
- Labeled-line principle - Across-fiber pattern principle
Transduction in the light: When light hits the photopigments...
- Light converts 11-cis-retinal in rhodopsin to all-trans-retinal thus releasing energy that... - activates the G-protein transducin which... - helps activate/create the enzyme cGMP phosphodiesterase which... - breaks down cGMP which was previously holding the Na+/Ca2+ channels open, closing the channels which... - leads to hyperpolarization which leads to... - decrease in glutamate secretion by rods which results in depolarization/disinhibition (aka almost excitation) of bipolar cells - The disinhibition of bipolar cells excites the ganglion cells through a receptor potential leading to a ganglion action potential
Who experiences color-blindness more and why?
- Males experience colorblindness more than females because they only need one defective X chromosome to experience colorblindness whereas females would need two defective X chromosomes to experience colorblindness • Tested for with special circles • Colorblind people do see some color they just don't see them the same as other people - Red-green color blind is most common - Can reach a pretty late age without realizing you're color blind because can interpret some color but in different hues
What type of vision do cones provide?
- Needs more light than cones; day vision - Provides visual acuity, responsible also for color vision
Two reasons why we never notice our blind spots
- Our brains fill in the gap; brain automatically likes to fill things in; takes info from around it, extrapolates and completes the image - Anything in the blind spot of one eye is visible to the other eye; blindspot of one eye is not in the same place as the other eye and both eyes are looking at the exact same thing except for the extremes
Inner ear
- Oval window - cochlea
Outer ear
- Pinna - External Auditory Canal
What type of vision do rods provide?
- Provides night vision as it does not need as much light as cones - Provides basic outlines of objects (contrast information)
What causes damage in closed head injuries
- Rotational forces that drive brain tissue against the inside of the skull - Blood clots that interrupt blood flow to the brain
cutaneous mechanoreceptors
- Ruffini's endings → sustained pressure - Meissner's corpuscle → changes in texture, slow vibrations - Pacinian corpuscle → deep pressure, fast vibrations - Merkel's disc → sustained touch and pressure - Free nerve endings
pain pathways
- Spinothalamic tract - Spinomesencephalic tract
Humans differ from chimpanzeesin two genes responsible for glucose transport:
- We have more of the protein that transports glucose into the brain - We have less of the protein that transports glucose into the muscles • Meaning we devotes more energy to our brains and less to physical strength
Sperry's eye rotation experiment
- Worked with newt/salamanders - Points in our visual field next to each other are organized next to each other in the brain - Cut the connection between the retinal area and the Tectum; then he twisted the eye around so that the retina was reversed
Color vision deficiency
- aka color blindness • except very few people actually see only in black and white - results when people with certain genes fail to develop one type of cone, or develop an abnormal type of cone
Properties of the stimulus (and how they influence perception)
- amplitude - frequency - purity
Functions of vestibular sensation
- balance; keeping head upright • in relation to gravity - adjustment of eye movements to compensate for the head movements
strabismus treatment
- treatment is to put a patch over the active eye and force attention to the other eye • works to some extent if begun early and if children comply with patch procedures - new treatment is to make kids play action video games which require the attention of both eyes
children born with cataracts not removed until age 7
- can see pictures but cannot understand them - had difficulty feeling a building block and pointing to a picture of it • a week later this skill improved • many other aspects of vision also improved - Motion perception and depth perception remained permanently impaired
tickle
- cannot tickle yourself like you cannot surprise yourself because it's expected - poorly understood sensation
V4
- color constancy (Retinex theory) • colors change in different lights - visual attention • certain things draw our attention
synesthesia fMRI cases studies
- different brain areas may be activated (than expected) - suggests some axons from one area have branches to other cortical regions (at least in some cases) OR you are on a hallucinogen! • are the brain areas involved cause or effect?
Reproduction
- egg survives 24-48 hours - sperm survives for 72 hours and in some cases 5-7 days • there is a pretty extended period of time during which you can get pregnant
pheromones in animals
- finding/attracting mate - identifying enemies/competition • male mice covered in female mouse urine will not be fought by other male mice
Where are neurotrophic factors from?
- glial cells, esp. astrocytes - target cells - incoming axons
pain chemicals
- glutamate - substance P
pioneer neurons
- growth cones (special parts of an immature axon or dendrite) • filopodia - needle like projections • lamellipodia - fanlike thin membrane - chemical signals in the environment that pulls neurons in the right directions; guided by chemokines - left by pioneer neurons?
taste transduction: sourness
- hydrogen ions (H+) with anions in acidic - close K+ channels resulting in action potential
a bipolar cell that receives excitation from a short wavelength cone (blue) and inhibition from long (red) and medium (green) wavelength cones
- increases its activity in response to short (blue) light and decreases in response to yellowish light - after prolonged exposure to blue light, the fatigued cells decreases its response - because a low level of response by that cell usually means yellow, you perceive yellow - see nothing at basal rate of firing - cannot see both blue and yellow at the same time with one neuron • different neurons can detect blue and yellow • because it takes opposing actions to convey message to the brain
meningitis --> encephalitis
- inflammation, infection of the meninges - flu-like symptoms - neck pain - if gets really inflamed, swelled causes pressure on the brain - can spread to the brain causing infection known as encephalitis
the earlier the training (aka therapy), the better
- just because someone isn't doing an ability doesn't mean they can't do it - is effort based though; more disfunction occurs when people feel tired, etc. • requires cognitive functioning
Phototransduction cascade
- light hits rhodopsin - breaks apart rhodopsin because the shape of rhodopsin is changing from 11-cis-retinal to all-trans-molecule - transducin is activated which activates cGMP phosphodiesterase which makes the channels close so glutamate is not released - hyperpolarization of rod decreases glutamate secretion, disinhibiting bipolar cells • bipolar have receptor potentials • ganglion cells have action potentials
Hair-follicle receptors
- located in Hair-covered skin - responds to Movements of hair
Krause end bulbs
- located in Mostly or entirely in hairless areas, perhaps including genitals - responds to uncertain
later mechanisms of recovery
- many surviving brain areas increase or reorganize their activity following damage, taking over the functions of the damaged area - OR they do not take over the functions of the damaged area, but compensate in other ways
omega-3 fatty acids during stroke
- may block apoptosis? - just is beneficial; don't know why
Taste transduction: salt
- metallic cation with small ion , e.g., NaCl - Na+ channels open because of Na in NaCla, causing action potential
when must tPA be administered
- must be administered within the first several hours because the cell is not going to last very long without oxygen and you're not going to get these cells back after they die so to prevent other deaths from happening, get rid of the clot
fetal alcohol syndrome (class)
- need a lot of alcohol; have mental abnormalities (smaller, less convoluted, asymmetrical brains [structure influences function]); have certain physical characteristics • Dose-response relationship
primary scents
- no primaries discovered • i.e. smell pizza but can't break it down into basic units that combine together to make the smell
Chemicals which increase pain
- nocebos - damaged tissue - strong, repeated stimulation
visual modules
- ocular dominance columns - orientation columns
Behavior in old age
- old people's memory and reasoning begin to fade - neurons lose some of their synapses and the remaining synapses change more slowly than before, etc. - exercise can help slow this - even the blood contains chemicals impairing cognitive function - BUT old people have more experiences • they do better than young people on certain kinds of questions • their brains become more active in some areas to compensate for loss of activity in others
vestibular sacs: saccule
- otolithic membrane (gelatinous membrane) with otoconia (little stones) • if membrane shifts due to gravitational force, little stones (otoconia) shift and pull on membrane which causes shearing of the hair cells and transduction to occur • otoconia can become misplaced and people can feel rattling/dizziness is head
Ventral stream receives
- parvocellular input = details - magnocellular input = movement - mixed input = brightness, color, & some shape
Pitch perception theories
- place theory - frequency theory - volley theory
stimuli of the somatosensory system
- pressure, mechanical deformation of skin - temperature - tissue damage/noxious stimuli - body position/movement of joints, tendons, muscles - lining of organs
MT/V5 (middle temporal cortex) and an adjacent region area MST (medial superior temporal cortex)
- receive input from the magnocellular path which detects overall patterns, including movement over large areas but is color insensitive - allow you to distinguish between the result of eye movements and the results of object movements
3 long fluid-filled tunnels
- scala vestibule - scala media - scala tympani
pregnancy tests
- use a pregnancy test after your missed period • measure HCG which is released from the embryo so you must be far along enough in your pregnancy to have an embryo and for HCG to accumulate
receptive field of End-stopped or hypercomplex cells
- size: larges of the V1 cells - rectangular - excitatory/inhibitory zones
itch pathways are...
- slow to respond and transmit at an unusually slow velocity - useful because it directs you to scratch the itchy area and remove whatever is irritating your skin
Bottom-up processing
- spots of light detected by photoreceptors → lines detected by cells in V1 → location of object by parietal lobe & form of object by temporal lobe - BUT: no "grandmother cell" • binding problem again
Pain modulation pathway: PNS trigger
- stimulate A beta fibers by rubbing skin around an injury but no the actual information → transmission neurons • will help interneurons to release interneurons to block the transmission of pain information - alpha beta fibers which transmit touch information
timbre
- timbre (quality) is how you can tell the difference between different types of sounds, e.g., violin vs. voice - tone quality or tone complexity
Herpes (virus)
- transmitted through Skin to skin contact even when nothing is visible - No affinity for eating neural tissue, but it hides out in the nervous system and travels out through the PNS to cause an outbreak • No cure - highly contagious
Retinal design does not interfere with visual acuity because the cells/neurons in front of the photoreceptors are
- transparent - small and unmyelinated in front of the fovea (dead center of the eye where cells move away to give a clear passageway) - dispersed away from the fovea
vestibular sacs
- utricle - saccule - depolarization, no action potentials
color vision
- visible lights consists of electromagnetic radiation within the range from less than 400 nm to more than 700 nm - ROYGBV • shortest visible wavelengths → violet • longest visible wavelengths → red - other species can see other wavelengths such as UV rays
3 kinds of evidence that determine heritability
1. Compare monozygotic ("from one egg") twins and dizygotic ("from two eggs") twins 2. Studies of adopted children 3. Identify specific genes linked to some behavior
two explanations for Blindsight
1. small islands of healthy tissue remain within an otherwise damaged visual cortex, not large enough to provide conscious perception but enough to support limited visual functions 2. the thalamus sends visual input to several other brain areas outside V1 including parts of the temporal cortex; after V1 damage, the connections to these other areas strengthen enough to produce certain kinds of experience despite a lack of conscious visual perceptions
Humans hear between
15-20 and 20,000 Hz • children hear higher frequencies • ability to perceive high frequencies decreases with age and exposure to loud noises
proteins consist of
20 amino acids and the order of those amino acids depends on the order of DNA and RNA bases
start of 4th week of fetal growth
3 swellings (forebrain, midbrain, hindbrain, then spinal cord)
Info from receptors below the head enters the spinal cord and passes toward the brain through
31 spinal nerves
7th week of fetal growth
5 swellings: • telencephalon (cerebral hemispheres) • diencephalon • mesencephalon (midbrain) • metencephalon • myelencephalon (medulla) • spinal cord
Continuous flash suppression
50% of people presented with visual stimuli in one eye while focusing on flashing stimuli with the other who did not have time to consciously perceive the not flashing stimuli, they correctly guessed where it was in their visual field
the first muscle movements occur at age...
7.5 week to stretch the muscles • spontaneous activity in the spinal cord drives all muscle functions at that age • sensory organs are not yet functional
topographic gradient hypothesis
According to this hypothesis, axons growing from one topographic surface (ex-the retina) to another (ex-the optic tectum) are guided to specific targets that are arranged on the terminal surface in the same way as the axons cell bodies are arranged on the original surrface. Growing axons are guided to their destinations by two intersecting signal gradients ( ex- an anterior-posterior gradient and a medial-lateral gradient.) • neurons are arranged in a particular way in relation to each other, on a coordinate system resulting from (at least) two intersecting chemical gradients. Thus, axons from these neurons form synapses which are arranged in the same way. • dorsal-ventral (top to bottom) gradient of protein muscles • medial to lateral (side to side) gradient of protein molecules (in retina) • third-dimensional layer • these two or three gradients are imposed and provide an individual set of coordinates for each • axons retain the spatial relationships based on two intersecting molecular gradients in the new location
Neuronal fatigue
After staring at one color in one location long enough, you fatigue that response and tend to swing to the opposite
What can interfere with receiving neurotrophic factors?
Alcohol - CNS depressant; if neurons are depressed, they are not stimulated meaning they're less likely to connect/active and exchange neurotrophic factors
insertional plaque
At an insertional plaque is an ion channel.
Transduction in the dark: In the dark when rod is at rest...
At rest, the rod continuously releases glutamate which acts as an inhibitor (NOT exciter like normal) and is slightly depolarization (-40mV) - cGMP holds cation channels open which allows for Na+ and Ca2+ inflow - rhodopsin (11-cis retinal + opsin) is found in the rod at rest - Na+ & Ca2+ cation channels are kept open via cGMP, allowing inflow into the rods, causing partial depolarization - Rods continuously releasing glutamate which, in this case, has an inhibitory effect on the bipolar neurons - Because bipolar neurons are inhibited, they cannot send receptor potentials to ganglion cells so no ganglion action potentials will occur
Complex Cell receptive field
BUT no opponent fashion receptive field; all areas seem to be receptive - size: simple cell < complex cell < hypercomplex cell - rectangular - no fixed excitatory/inhibitory zones
Simple cells Receptive field
Bar- or edge-shaped, with fixed excitatory and inhibitory zones
Complex Cell Receptive field
Bar- or edge-shaped, without fixed excitatory or inhibitory zones
Before Mendel, it was thought that inheritance was...
Before Mendel, it was thought that inheritance was a blending process in which the properties of the egg and the sperm mixed like paint
biologists infer evolution from
Biologists infer evolution from fossils and comparisons of living species
neurons/axons are guided by...
Cell Adhesion Molecules (CAMs) such as immunoglobulins, as well as neurotrophic factors.
Where are cones concentrated?
Concentrated in center of retina; Fovea only contains cones
Where are rods concentrated?
Concentrated right outside the fovea; that is, more in the periphery; extreme periphery of retina does not have photoreceptors
Foveal Vision Receptors
Cones
When are cones super activated
Cones are super activated when detects favorite wavelength; still responds a little bit to other wavelengths but not as much as to its favor wavelength
How do the cones signal to the bipolar neuron that it detects blue?
Cones have increased activity at blue cone and decreased activity at green and red cones
How do the cones signal to the bipolar neuron that it sees yellow?
Cones have increased activity at green and red cones and decreased activity at blue
Parvocellular Neurons Respond to
Detailed analysis of stationary objects
Foveal Vision Convergence of input
Each ganglion cell excited by a single cone
Peripheral Vision Convergence of input
Each ganglion cell excited by many receptors
mTOR
FACILITATES axon regrowth; unsure why
Ferret Experiment: birth
Ferrets are born so immature that their optic nerves (from the eyes) have not yet reached the thalamus
Brain reorganization can go too far, especially in musicians
Focal hand dystonia
Cone convergence
Fovea: cones have a 1:1 convergence onto bipolar cells (no information is lost as it is past; very acute vision giving you details)
Foveal Vision Color vision
Good (many cones)
Foveal Vision Sensitivity to detail
Good detail vision because each cone's own ganglion cell sends a message to the brain
acid receptor stimuli
H+ (in acidic solution)
Retinal location of Parvocellular Neurons
In and near fovea
morphine and other pain-decreasing measures and itch
Morphine and other measures that tend to decrease pain tend to increase itch • means itch is not a type of pain
Law of Specific Nerve Energies
Johannes Muller's (1838) insight that whatever excites a particular nerve establishes a special kind of energy unique to that nerve • the brain somehow interprets the action potentials from the auditory nerve as sounds, those from the olfactory nerve as odors, and so forth • Ex → you see flashes of light when you rub your eyes because you have mechanically excited the visual receptors in your eyes
LGN converges they info onto...
LGN converges their information onto fewer simple cells; LGN neurons converge their data onto one V1 cortical simple cell
Receptive fields of Magnocellular Neurons
Larger
cell bodies of Magnocellular Neurons
Larger
What type of cones are most abundant?
Long (red) and medium (green) wavelength cones are far more abundant than short wavelength (blue) cones and are distributed more haphazardly across the retina whereas the short cones are distributed about evenly • Variations, though, produce only small differences in people's color perception
two especially important areas for motion perception
MT/V5 (middle temporal cortex) and an adjacent region area MST (medial superior temporal cortex)
Punch-drunk Syndrome aka Pugilistic Parkinson's syndrome
Mohammad Ali → has symptoms that look like Parkinson's and cognitive malfunctions as well; got this from too many concussions from boxing
Receptive fields of Koniocellular Neurons
Mostly small, variable
Magnocellular Neurons Respond to
Movements and broad outlines of shape
receptive field of simple cells
NO longer circular - size: LGN < simple cell < complex cell -rectangular - fixed excitatory/inhibitory zones similar to bipolar and ganglion
what is special about the olfactory system?
NOT routed through the thalamus - only sense not routed through the thalamus
salty receptor stimuli
NaCl (cation with anion)
How does the bipolar neuron then tell the brain that it sees blue?
Neuron is stimulated to show it sees blue
olfactory pathway II
Olfactory cilia → thru cribiform plate → ipsilateral olfactory bulb → pyriform cortex & entorhinal cortex (where the primary cortex for the olfactory system lies) & amygdala & hypothalamus & hippocampus & orbitorfrontal cortex
Cone sensitivity
Not as sensitive = 10s or 100s of photons needed; can quickly adapt to the dark but cannot adapt as thoroughly to dim situations (as compared with rods) (may miss some photons but know exactly where photon came from)
ferret study: test
Now do a test to answer your original question about the temporal cortex: Flash the red light in the right visual field so that the left (rewired) hemisphere see it. Which way with the ferret turn?
new neurons later in life: now know
Now know there are exceptions to this thought • Olfactory receptors in rodents • Hippocampal neurons in rodents
What does order of the bases determine?
Order of bases determines the order of corresponding bases along an RNA molecule → adenine, guanine, cytosine, and uracil
Divisions of the ear
Outer, middle, and inner ear
How do people communication with sound?
People communicate emotion by alterations in pitch, loudness, and timbre - prosody
Common misunderstanding about evolution
People have not stopped evolving even though we are no longer subject to survival of the fittest because people who have more children than others will still spread their genes more
transduction pathway
Photoreceptors → horizontal cells → bipolar cells → amacrine cells → ganglion cells → optic disk → optic chiasm → dorsal lateral geniculate nucleus (thalamus) → primary visual cortex (area V1 in the occipital lobe)
Peripheral Vision Color vision
Poor (few cones)
Peripheral Vision Sensitivity to detail
Poor detail vision because many receptors converge their input onto a given ganglion cell
Peripheral Vision Receptors
Proportion of rods increases toward periphery
simple cells respond to
Respond more to horizontal and vertical orientations than to diagonal ones
respond to pheromones...
Respond to pheromones in very low concentrations continuously even after prolonged periods of time
Peripheral Vision Brightness sensitivity
Responds well to dim light; poor for distinguishing among bright lights
cell bodies of Koniocellular Neurons
Small
Receptive fields of Parvocellular Neurons
Smaller
Where do rods converge their information?
Rods converge their info onto fewer bipolar cells (sometimes information gets lost so rods are not in charge of acute vision, details but are super sensitive)
End-stopped or hypercomplex cells Receptive field
Same as complex cell but with strong inhibitory zone at one end
herpes in men vs women
Seen in men on the skin but in women it often occurs on the cervix inside of them
2. Studies of adopted children
Similarities between adopted child and genetic mother could indicate genetic influences and prenatal environment
Sperry's chemoaffinity hypothesis
Sperry's hypothesis that each postsynaptic surface in the nervous system releases a specific chemical label and that each growing axon is attracted by the label to its postsynaptic target during both neural development and regeneration. This hypothesis does not account for the fact that some axons follow exactly the same circuitous route to reach their target rather than growing directly to it. - each post-synaptic membrane releases a chemical which attracts the growing axon. - neurons make connections with their targets based on interactions with specific molecular markers[1] and, therefore, that the initial wiring diagram of an organism is (indirectly) determined by its genotype - axons differentially recognize chemical signals produced by target matching cells. In this way, neurons connect only to specific cells or groups of cells.
Why is drinking alcohol during the early adolescent years also an issue?
Synaptogenesis - occurs during the early adolescent years • If alcohol is introduced to suppress CNS activity, synaptogenesis does not occur so neurons will die • Marijuana during adolescent years can cause a 10 point drop in IQ
taste transduction: sweet
T1R2 + T1R3 • big cats don't have sweet receptors
problem with tPA
TOXIC to brain cells → means clot in blood vessel is fine because BBB will prevent tPA from entering brain → but can't be used when attacking brain cells/hemorrhage - tPA would worsen hemorrhage because in thins blood which encourages bleeding
cilia
The cilia (hairs) exist in bundles where each cilium is tethered to its neighbor by a filament called a tip link. The cilia in a bundle are arranged in increasing length, from shortest to longest. The tip links join the tip of one cilium to the side of its neighbor, at a region called an insertional plaque
Optic Radiations
The geniculo-calcarine tract (also known as the optic radiation) is a collection of axons from relay neurons in the lateral geniculate nucleus of the thalamus carrying visual information to the visual cortex (also called striate cortex) along the calcarine fissure. There is one such tract on each side of the brain
Rita Levi-Montalcini
discovered that the muscles do not determine how many axons form, but how many survive
How does the nervous system determine the color and brightness of the light?
The nervous system determines the color and brightness of the light by comparing the responses of different types of cones
Proprioception
The unconscious perception of movement and spatial orientation arising from stimuli within the body itself. In humans, these stimuli are detected by nerves within the body itself, as well as by the semicircular canals of the inner ear - Mechanoreceptors • Muscle spindle receptors, Ruffini Corpuscles, Merkel cells, etc
Used to think genes had...
discrete locations → many genes do not have the discrete locations we once imagined
Retinal location of Magnocellular Neurons
Through the retina
Retinal location of Koniocellular Neurons
Throughout the retina
Middle Ear
Tympanic membrane
Simple cells location
V1
Complex Cell location
V1 and V2
End-stopped or hypercomplex cells location
V1 and V2
Microdeltion or microduplication
When happens to a tiny part - May explain schizophrenia
scala vestibule
has oval window on one end which the stapes bangs on moving fluid around; the upper bony passage of the cochlea
Rod sensitivity
Very sensitive = 1 photon is enough; can more thoroughly adapt to darkness May not know exactly where light came from
1. Compare monozygotic ("from one egg") twins and dizygotic ("from two eggs") twins
When monozygotic twins act similarly, it is likely due to genetics but it could be environment because people who look alike are often treated alike
scala media
Within the scala media → lie the auditory receptors on the basilar membrane; Organ of Corti located here
Will the nerves go back to the right place supporting the chemoaffinity hypothesis?
YES; doesn't matter where you start off, you're going to move up the chemical gradient and still find the correct space
Color sensitivity of Parvocellular Neurons
Yes
3. Identify specific genes linked to some behavior
\Risks reporting a false association → should not trust until replicated in other populations
Astigmatism
a blurring of vision lines in one direction caused by an asymmetric curvature of the eyes - occurs in 70% of infants - normal growth reduces the prevalence of astigmatism to about 10% in 4-year-old children
cochlea
a bony, spiral-shaped, fluid-filled tube in the inner ear through which sound waves travel and trigger nerve impulses; • 3 long fluid-filled tunnels
Simple cell
a cell with a bar-shaped or edge-shaped receptive field with fixed excitatory and inhibitory zones • The more light shines in the excitatory zone the more the cell responds and vice versa
Evolution
a change over generations in the frequencies of various genes in a population
Capsaicin and pain
a chemical in hot peppers that stimulates receptors for heat - Produces burning when rubbed on painful area followed by a longer period of decreased pain - Causes an excessive buildup of calcium in heat receptors and damages the mitochondria in those cells rendering them nonfunctional for a time - depletes substance P • causes receptors to deplete supply of substance p by causing a burning pain for a bit which is then followed by period of decreased/no pain because there is no substance p
neurotrophin
a chemical that promotes the survival and activity of neurons - The brain also responds to brain-derived neurotrophic factors (BDNF → important in depression) and several other neurotrophins - Essential for growth of axons and dendrites, formation of new synapses, and learning but do NOT control survival of neurons • Neurons may require input from other neurons to survive
itch
has special receptors and special spinal cord pathways
fetal alcohol syndrome
a condition marked by hyperactivity, impulsiveness, difficulty maintaining attention, varying degrees of mental retardation, motor problems, heart defects, and facial abnormalities caused by mothers who drink heavily during pregnancy • Thinning of the cerebral cortex that persists into adulthood • Directly correlated with amount mother drinks
phantom limb
a continuing sensation of an amputated body part • may be tingle or pain; occasional to constant; last days, week, or lifetime • develop when the relevant portion of the somatosensory cortex reorganizes and becomes responsive to alternative inputs - Ex → Axons representing the effects come to activate the cortical area previously devoted to an amputated hand • A touch on the face now produces a facial sensation but also a sensation in the phantom hand
Many older people have...
a decrease in their inhibitory neurotransmitters in the auditory portions of the brains → have trouble suppressing the irrelevant sounds and attending to important ones
tissue plasminogen activator (tPA)
a drug that breaks up blood clots - patients must receive 4.5 hours after a stroke but most stroke victims don't go to the hospital fast enough - could make hemorrhage worse if that's what's going on, but ischemia is so much more common that they risk it
how genes affect behavior
a gene that does something does not directly make it happen → produces a protein that makes it happen or produces a protein that under certain circumstances increases the probability of alcoholism
Dominant gene
a gene that shows a strong effect in either the homozygous or heterozygous condition o Ex → brown eyes; high sensitivity for PTC
Recessive gene
a gene that shows its effects on in the homozygous condition o Ex → blue eyes; low sensitivity for PTC
Phenylketonuria (PKU)
a genetic inability to metabolize the amino acid phenylalanine - If PKU is not treated → phenylalanine accumulates to toxic levels, impairing brain development and leaving a child mentally retarded, restless, and irritable - ~ 1% of Europeans carry this recessive gene (*Jewish?) - Can be modified by environmental interventions → diet low in phenylalanine • Diet is difficult to stick to and must be maintained for life
Mutation
a heritable change in a DNA molecules • Ex → changing one base in DNA to any of the other three types means that the mutant gene will code for protein with a different amino acid at one location in the molecule • Rarely advantageous
Dermatome
a limited area of the body which a certain spinal nerve innervates • Overlaps similar dermatomes 1/3 to 1/2
Oval window
a membrane of the inner ear which vibrates due to movements of the stirrup • The vibrations of the oval window occur at the entrance of the scala vestibule which sets into motion the fluid of the cochlea
homeobox genes
a series of genes that regulate the expression of other genes and control the start of anatomical development (i.e. front vs. rear) - All share a large sequence of DNA bases, a mutation of which could cause mental retardation and physical deformities
Volley principle: for slightly higher frequencies
a set of neurons may take turns firing, to represent the frequency of the soundwave (so now, a neuron may not fire at every peak, but may fire at every fourth peak, while other neurons are firing at the 2nd peak, the 3rd peak, etc.)
Vomeronasal organ (VNO)
a set of receptors located near, but separate from the olfactory receptors • Respond only to pheromones
closed head injury
a sharp blow to the head that does not puncture the brain (young people) - Repeated and severe head injuries are the most severe - contusion - concussion
suggests that practicing a skill
a skill reorganizes the brain to maximize the performance of that skill - OR that brain characteristics that were present from birth attract people to one occupation or another • not always adaptive → focal hand dystonia & writer's cramp
ischemia
a stroke that is the result of a blood clot or other obstruction in an artery - Neurons deprived of blood lose much of their oxygen and glucose supplies - e.g., atherosclerosis (blood vessel clogged with build up [cholesterol, other particles] which causes a blood clot over the plaque) → embolism (pieces of the blood clot/plaque fall off and travel through the blood stream) • problem when it gets to a small blood vessel because it may get lodged there and blood stops moving • brain cells can only live without oxygen for ~3 minutes
Hippocampal neurons in rodents
a supply of new neurons keep the hippocampus "young" for learning new tasks
Stroke
a temporary interruption of normal blood flow to a brain area (aka cerebrovascular accident); cerebrovascular accident → problem at much older age; same process that causes stroke is the same as what causes cardiovascular disease; differences → CVS results in the heart damage; stroke results in neuron damage • 3rd common cause of death
Lamarckian evolution
a theory that evolution occurs through the inheritance of acquired characteristics - common misunderstanding of evolution
fovea
a tiny area in the central portion of the retina packed tightly with receptors specialized for acute, detailed vision • almost devoid of bloods vessels and ganglion cells axons allowing for nearly unimpeded vision • Each receptor in the fovea connects to a single bipolar cells which connects to a single ganglion cell with an axon to the brain
Those deaf in one ear...
adapt to sound localization by recognizing louder sounds are nearer their intact ear and softer sounds are nearer their deaf ear
parietal cortex
location of objects, esp. in relation to our body
prefrontal cortex and pain
logic to avoid pain next time
Stereoscopic depth perception
achieved by comparing the inputs from the two eyes • requires the brain to detect retinal disparity
sour receptors detect...
acids
all cells have the same DNA as all other cells but
activity can vary→ except RBC which have no DNA
conscious visual perception requires
activity in area V1
viewing a complex moving pattern activates brain areas among
all four lobes of the cerebral cortex
taste info from the posterior tongue and the throat travels...
along branches of the 9th and 10th cranial nerve
Group selection
altruistic groups thrive better than less cooperative ones - True but problematic → even if cooperative groups do well, an uncooperative individual in the group gains an advantage - Does work when cooperative individuals do most of their interactions with one another • Works especially well for humans because we can punish or expel uncooperative humans
Bipolar cells make synapses onto
amacrine cells and ganglion cells
Altruistic behavior
an action that benefits someone other than the actor; helping a nonrelative without immediately getting something in return • Genes that encourage altruism help other individuals survive and spread their genes → humans certainly have this (donating to charities, helping others, etc.)
Lens/Ciliary Muscle and Ligaments
an adjustable structure that focuses the light to the back of the eye • when lense is curved incorrectly, nearsightedness or farsightedness
receptive field
an area in a visual space that excites or inhibits a receptor cell
Association Areas
extra striate cortex ventral pathway dorsal pathway
Visual agnosia
an inability to recognize objects despite otherwise satisfactory vision • usually results from damage in the temporal cortex • can describe the object but not name it
heterozygous
an individual with an unmatched pair of genes
nocebos
an inert substance or form of therapy that creates harmful effects in a patient - opposite of placebo
Pupil
an opening in the center of the iris where light enters
things in middle are
analyzed by both temporal hemi retinal areas
low frequency sounds are more...
anterior & lateral
anencephaly
anterior portion of the neural tube has not submerged properly; the brain is exposed to the environment - babies are either miscarried or stillborn
difference in time of arrival at the two ears
any frequency, but especially lower frequencies • auditory nerves are already slightly depolarized so that they can react super-sensitively to when sound starts and stop • a sound to the right will arrives at the right ear first and the left ear slightly later
human brains
are different in many ways that aren't understood well - Human have many genes active in brain development that do not occur in other mammals → genes exert their effects especially in the prefrontal cortex (memory, attention, speech, decision making)
Olfactory receptors in rodents
are exposed to the outside world (i.e. toxic chemicals) and have a ½ life of only 90 days - Stem cells in the nose remain immature throughout life and periodically divide so that one remains immature and one differentiates to replace a dying olfactory receptor which grows its axon backwards
Nontasters
are less sensitive than average to other tastes
blind spot
area at the back of the retina where the optic nerve exits; it is devoid of receptors meaning all light that hits this area is not converted into neural signals so it can't be "seen"
Aqueous Chamber
area behind the cornea before the pupil filled with fluid
Secondary visual cortex (area V2)
area of the brain which processes the information further and transmits it to additional areas
behavior changes as..
as people grow older
the ocular dominance & orientation columns are
at 90 degrees to each other
pain pathway decussates...
at the level of the spinal cord
what is also a mechanical sense?
audition is also one because the hair cells move but it is more complex and important so considered separately
Music training usually beginning in childhood
auditory cortexes of musicians were twice as strong as those in nonmusicians; temporal cortex of the right hemisphere is 30% larger; gray matter was thicker in several cortical areas of musicians and thinner in others
People vary substantially in the number of
axons in their optic nerve and the size of their visual cortex due to genes • Ex → top tennis and squash players have faster visual responses to stimuli
The sympathetic nervous system sends....
axons to muscles and glands forming far more neurons than it needs
not all RNA codes for proteins
many RNA molecules perform regulatory functions
newborn babies are predisposed to pay more attention to
faces than other stationary displays • this face simply must have the eyes on top to garner attention, but does not have to be realistic
in humans, pheromones...
can alter skin temperature & other ANS responses (e.g., hypothalamic activity)
Retina
back surface of the eye lined with visual receptors; several layers of neurons deep in the back of the eye; basically piece of brain in eye - light from the left side of the world strikes the right half of the retina and vice verse - light from above strikes the bottom half, and vice versa • this does not pose a problem because the visual system does not duplicate images but codes various kinds of neuronal activity
Pacinian corpuscles
bare ending surrounded by other cells that modify its function • Onion-like structure that provides mechanical support to resist gradual or constant pressure → insulates nerve against most stimuli - located in Both hairy and hairless skin
An axon that does not receive NGF...
because it does not connect to the right postsynaptic cell by a certain age degenerates/dies - Apoptosis: programmed mechanism of cell death • NGF cancels apoptosis
deaf people and supersensitivity
become more sensitive to touch and vision which become activated in the auditory (temporal) cortex
as visual info goes from the simple cells to the complex cells and then to other brain areas, the receptive fields
become more specialized
almost all survivors of brain damage show
behavioral recovery to some degree, some of which relies on the growth of new branches of axons and dendrites
new neurons later in life: late 1800s
believed all neurons were formed in embryological development or early infancy at the latest • beyond this, neurons could be modified but not created anew
Paul Weiss (1924)
believed axons grew attaching to muscles at random and then sent messages tuned to different muscles, like radios • this approach was WRONG • axons actually find the correct muscle they're supposed to control
Collateral sprouting
beneficial; neurons around the damaged one literally sprout out new branches like dendrites) • mTOR increases sprouting - kids have more mTOR than adults • neurotrophins - surviving cells • related axons • unrelated axons
Humans have
bigger and better brains than other species allowing us to create new solutions to problems we have never faced
for cats and primates, most neurons in the visual cortex receive
binocular input
enzymes
biological catalysts that regulate chemical reactions in the body
Opposite of motion blindness can occur
blind except for the ability to detect which direction something is moving; see motion without seeing the objects that are moving • even after extensive damage to V1, area MT which gets some input directly from the lateral geniculate nucleus of the thalamus could still get enough input to permit motion detection
NSAIDs and pain
blocks prostaglandins - Ibuprofen, motrin
Vision theory today
both are correct; depends on level we're talking about - photoreceptors → trichromatic theory • cones - bipolar cells onward → opponent process theory • how rest of neurons process color information
relative firing
brain cannot tell the color of light by just looking at one cone because all cones are activated by white light so brain must look at relative activity to see what color it is (all cones are activated means white/sunlight that has all color; recognizes one cone is active, two others aren't then its one color
chorda tympani
branch of the seventh cranial (facial) nerve
prefrontal cortex responds...
briefly to light, sound, touch but responds continuously as long as pain lasts
decrease stimulation during stroke by...
by blocking glutamate synapse or blocking calcium entry (glutamate inhibitor) - too much glutamate release causing overactivation; the idea is that inhibiting glutamate will decrease overactivation
frequency theory: change pitch
by changing frequency of action potential firing
frequency theory: change loudness
by changing number of neurons that are firing action potentials
effects of a stroke
can be barely noticeable to fatal - Edema - Impair the sodium-potassium pump - Combo of edema and excess sodium
pluripotent cells
can become still many things but now limited to each layer - the cells also differentiate, such that eventually, the embryo is composed of an endoderm, mesoderm, & ectoderm. - These cells are specialized - Can become endoderm, mesoderm, or ectoderm cells but NOT an entire organism as totipotent cells can become
otoliths
calcium carbonate particles that push against different sets of hair cells when the head tilts in different directions
mesoderm
can only become kidneys, reproductive organs, bones, muscles, vascular system
ectoderm
can only become skin, nervous system
endoderm
can only intestines, the lungs, & liver • due to differentiation
over-enriched environment
cannot bypass biological limitations that an organism might have • Over stimulation of premature infants can cause bleeding of brain
bodies
cause a stronger reaction than other stimuli in an area close the face area (part of the fusiform gyrus)
faces
cause a stronger reaction than other stimuli in part of the fusiform gyrus of the inferior temporal cortex, especially in the right hemisphere
1. A cut in the nervous system causes
causes a scar to form causing a mechanical barrier - Researchers developed a way to build a protein bridge, providing a path for axons to regenerate across a scar-filled gap
pictures of places
causes a strong response in the parahippocampal cortex (next to the hippocampus)
reliving recent break-ups
causes activity in the cingulate cortex and sensory areas responsive to physical pain
acceleration of the head
causes jellylike substance to push against the hair cells initiated action potentials
Adding Acetyl groups (COCH3) to the histone tail near a gene
causes the histones to loosen their grip on the DNA, and facilitates the expression of a gene
Removal of acetyl groups
causes the histones to tighten their grip on the DNA turning the gene off
behavioral deficits after stroke may be due to
cell death, as described above but also... - Diaschisis
in apoptosis...
cell will package up all bad chemicals neatly, so they have a good death and don't irritate nearby cells with chemicals - only problematic during stroke
what cells are affected during stroke?
cells in the acute area of stroke, as well as penumbra...
Complex cells
cells located in areas V1 and V2 that do not respond to the exact location of a stimulus but to a pattern of light in a particular orientation anywhere within its large receptive field
End-stopped or hypercomplex cells
cells that resemble complex cells except that they have a strong inhibitory area at one end of their bar-shaped receptive field - orientation & movement/direction preference - inhibitory zone (lines of certain lengths) • looking for end zone
itch axons activate...
certain neurons in the spinal cord that produce a chemical called gastrin-releasing peptide - blocking this peptide can decreases scratching in mice
Capsaicin
chemical found in hot peppers that stimulated the receptors for painful heat
taste stimuli
chemicals • molecules dissolved in saliva • primary tastes & molecules
Photopigments
chemicals in both rods and cones that release energy when struck by light
Cannabinoids and pain
chemicals related to marijuana that can also block certain types of pain • Unlike opiates, act mainly in the periphery of the body rather than in the CNS and work in different ways, managing pain that maybe opioids can't
pheromones
chemicals released by an animal that affect the behavior of other members of the same species
immunoglobulins and chemokines
chemicals that guide neuron migration • Deficit in these chemicals leads to impaired migration, decreased brain size, decreased axon growth and mental retardation
deafferentiation monkeys
choose not to use a Deafferented limb unless forced to - reflects that sometimes a person or animal with brain damage appears to be unable to use something but is simply not trying
hair cells have...
cilia (more fine hair cells)
brain damage in young people
closed head injury
receptive fields bipolar cells
co-centric receptive fields
cytochrome oxidase blobs
color analysis
Iris
colored muscular ring around the pupil that adjusts the pupil's size - different colored irises → genetic variation because color affects how much light is absorbed giving you clearer vision
orientation columns
columns of cells that each prefer a different orientation of line
ocular dominance columns
columns of cells that each prefer the same type of column; each cell prefers the same line orientation but receive different percentages of input from each eye
flavor
combination of taste and smell
determining the direction and distance of a sounds requires
comparing the responses of the two ears
Inferior temporal cortex
complex shape analysis - shape constancy
Photopigments consist of
consist of a derivative of vitamin a (11-cis-retinal)bound to proteins called opsins which modify the photopigments sensitivity to different wavelengths of light
cells that respond to the sight of a particular object
continue responding about the same way despite changes in its position, size, and angle - these cells learn to recognize all the different views as being the same object
auditory pathway connections
contralateral & ipsilateral connections but predominantly contralateral • 8th cranial nerve → ipsilateral cochlear nuclei (medulla) then splits apart....
Lateral inhibition provides...
contrast → the brain will be able to loudly hear the cells that has a message for the brain and the other cells will quiet
taste and smell axons...
converge onto many of the same cells in an area called the endopiriform cortex
prosody
conveying emotional information by tone of voice
why is olfaction critical
critical for finding food and avoiding danger • much of flavor is smell
the brain is very adept at
detecting biological motion
vestibular sensation
detects the position and movement of the head
The various areas of the somatosensory thalamus send their impulses to
different areas of the primary somatosensory cortex located in the parietal lobe • various aspects of body sensation remain mostly separate all the way to the cortex
different odors
different pattern of glomeruli (& thus, olfactory cortex) activation
taste: different chemicals excite...
different receptors and produce different rhythms of action potentials per unit of time
LGN (lateral geniculate nucleus of the thalamus)
different types of ganglion cells project to different parts of the thalamus
damage to the Inferior temporal cortex
damage = visual agnosia, prosopagnosia, lack of shape constancy • if only damage fusiform gyrus of the temporal cortex then you have not knowing instances of a particular category (i.e. can recognize a face is coming toward you but not which face) → prosopagnosia - causes objects to no longer be constant at they are moving away from you; they begin to look like different shapes
Motion deafness
damage in the superior temporal cortex causes people to be able to hear sounds but be unable to detect that a source of sound is moving
damage to the dorsal stream
damage to the dorsal stream means people can see objects but they don't integrate their vision well with their arm and leg movements
within a mature mammalian brain or spinal cord
damaged axons do not regenerate, or do so only slightly 1. cut 2. pull apart 3. glia
adult women react to sweaty men as...
danger signals - secrete cortisol
insensitivity to pain is...
dangerous but controlling it is adaptive
Nerve deafness/Inner-ear deafness
deafness causes by damage to the cochlea, the hair cells, or the auditory nerve; damage to cochlea/hair cells • can be inherited, result from disease, or exposure to loud noises • nerve damage is permanent • may use cochlear implant to stimulate nerves with sound • often produces tinnitus
Diaschisis and what can help
decreased activity of surviving neurons after damage to other neurons • if Diaschisis contributes to behavioral deficits following brain damage, then increased stimulation should help
prolonged exposure to a given visual feature
decreases sensitivity to that feature, as if it fatigued relevant detectors
hypnotic suggestion to feel no pain...
decreases the responses in the cingulate cortex without much effect on the somatosensory cortex - still feels the pain but reacts with emotional indifference
touch pathway decussates...
decussates at the level of the medulla (see above)
Auditory response to one sound is...
delayed and may partially overlap with another sound response
When one of its neurons forms a synapse onto a muscle...
delivers NGF
Gregor Mendel (late 1800s)
demonstrated that inheritance occurs through genes
when we're older learning occurs as...
dendrites grow new branches, not because your whole brain grows but when you're younger development is correlated with brain growth
shearing force on cilia in ampulla
depolarization, no action potentials here
family of 25 receptors...
detect bitterness • allows us to detect a great variety of dangerous chemicals BUT cannot detect them in low concentrations because there are so few of each type of receptor • may also trigger coughing and sneezing to expel them if smelled
Conductive deafness/Middle-ear deafness
diseases, infections, or tumorous bone growth can prevent the middle ear from transmitting sound waves properly to the cochlea; damage to ossicles • sometimes temporary • can be corrected by surgery or hearing aids • suffers can hear themselves clearly because the vibrations come from inside but they cannot hear others
Early in the development, the cells lining the ventricles of the brain...
divide • Some cells remain where they are as stem cells continuing to divide • Others become neurons and glia that migrate to other locations
symmetrical division
division of a founder cell that gives rise to two identical founder cells
Damage to area A1
does NOT cause deafness; people with damage here have trouble with speech and music but they identify and localize single sounds reasonably well • Means that cortex is necessary for processing hearing information but not necessary for actually hearing
Infant grasp reflex
doesn't help anything in humans today; but in monkey ancestors, babies needed to be able to hold onto their mothers when the mother ran from a predator or looked for food; a weak grasp would jeopardize their life
multipotent cell
doesn't matter what layer you're part of, but what system you're part of - i.e. cells in nervous system can only become more specialized nervous system cells - ~18 days after conception, the cells of the neural plate form. These cells are multipotent/neural stem cells - groove in ectoderm forms and thickens until it forms the neural tube
Your brain encodes sight information in a way that
doesn't resemble what you see → stores a representation of sights in terms of altered activity in many neurons
genes are...
dominant, recessive, or intermediate
concussion
don't necessarily see physical or structural evidence but... • there's a disturbance of consciousness → may be result of contusion - avoid stimulation of all sort to give brain a rest, to give it a chance to heal • Punch-drunk Syndrome aka Pugilistic Parkinson's syndrome
when is proliferation done by?
done by birth - (most things)
Placebos and pain
drugs or other procedure with no pharmacological effects but that can cause decreases in perceptions of pain and activity in parts of the brain that signal pain • do so in party due to relaxation and distraction but that's not the whole explanation • inhibits cingulate gyrus & increases opiate release
neural tube defects
e.g., spina bifida, anencephaly
Across-fiber pattern principle
each receptor responds to a wider range of stimuli, and a given response by a given axon means little except in comparison to what other axons are doing
Labeled-line principle
each receptor would respond to a limited range of stimuli and the meaning would depend entirely on which neurons are active
early development across species
early development is very similar across species
neuronal death/apoptosis
early on do not want, but later in life is used to mature the brain (maturation includes pruning synapses) - initially, 50% more neurons - does not occur uniformly - normal...sign of maturation
Bipolar cells are specially designed to detect
edges
Ruffini endings
elaborated neuron ending - located in Both hairy and hairless skin - responds to Stretch of skin
Meissner's corpuscles
elaborated neuron ending - located in Hairless areas - responds to Sudden displacement of skin; low frequency
Stimulus for Vision
electromagnetic radiation
mice with deletion of gene for K+ channels
enhanced smell - deleting potassium channel genes in mice caused them to be able to smell better
Physical activity in elderly people
enhances both cognitive processes and brain anatomy
A stimulating environment...
enhances sprouting of axons and dendrites in many species • stimulating can be interesting experiences and social interactions OR physical activity
Primary somatosensory cortex is...
essential for touch information • activity in cortex responds to what you experience not what is stimulated in receptors • damage → impairs body perceptions
receptive fields hypercomplex cells
even larger, inhibitory zone
receptive fields complex cells
even larger, no fixed excitatory/inhibitory zones
Lateral inhibition: the receptors send messages to
excite the closest bipolar cells and also send messages to slightly inhibit them and the neighbors to their sides - this heightens the contrast between an illuminated area and its darker surroundings
pain
experience evoked by harmful stimuli, directs your attention toward a danger
Why is alcohol an issue with prenatal neural development?
fetal alcohol syndrome
several V1 complex cells also converge their information onto
fewer hypercomplex cells; several V1 complex cells converge their data onto one hypercomplex V1 neuron
Distribution of receptors: hairy skin
fewer number and fewer variety of receptors - free nerve endings, Ruffini corpuscles, Pacinian corpuscles - but can tell when people are just above hairy skin because hair movement is detected by receptors around base of hair (hair shaft sensory receptor
Epigenetics
field of study that deals with changes in gene expression (that alter gene expression for longer periods of time)
hair cells do NOT
fire action potentials
farsightedness
focuses light past back of eye • can do corrective surgery or wear corrective lenses
nearsightedness
focuses light short of back of eye • much more common
How does the basilar membrane work in place theory?
for very high frequencies of sound, the basilar membrane works like keys on a piano • that is, the neurons along the length of the basilar membrane all have a preference for a particular frequency of sound
some proteins
form part of the structure of the body, become enzymes
What type of detectors are simple cells
form/orientation detectors; sensitive to line orientation
Roger sperry
former student of Weiss that showed how sensory axons find their correct targets; chemoaffinity hypothesis • Weiss cut the optic nerve and inverted the eye of salamanders → the axons grew back to their original targets, NOT to the targets corresponding to the eye's current position • target membranes release a specific chemical which attracts a particular axon (or type of axon) to grow towards it - diffusible chemical
Charles Darwin
founder of evolutionary theory
Tinnitus
frequent or constant ringing in the ears
hair cells lined up from
from tallest to smallest and are mechanically gated • movement causes ion channel to open or remain closed
people who develop expertise at almost any type of visual stimulus show
fusiform gyrus responses when they look at items within their field of interest
the bipolar cells send their messages to
ganglion cells
Optic Nerve
ganglion cells axons that exit through the a hole in the back of the eye called the optic disk and continue to the brain
pheromones in humans vs animals
generally more subtle in humans and stronger in animals
Everything you do depends on
genes and their environment
Autosomal
genes on all other autosomal chromosomes
Sex limited genes
genes present in both sexes but active mainly in one sex - Ex → genes that control the amount of chest hair in men, breast size in women, amount of crowing in roosters, egg production in hens • Both sexes have these but sex hormones activate the genes in one sex or the other • Many show their effects at puberty
brown/black eyes
give you better vision and is dominant
Cytosine, Adenine, Guanine
glutamate
mild pain releases...
glutamate
umami receptor stimuli
glutamate
Dorsal stream goes to
goes toward dorsal side
Ventral stream goes to
goes toward ventral side
tangential migration
going parallel to the length of the neural tube; skimming the sides
Cortical plasticity
greatest in early life, but never ends
cells with similar properties
group together in the visual cortex in columns perpendicular to the surface • cells within a given column process similar information
taste buds
groups of receptors on the tongue
brain cooling in one woman
had a hiking accident and fell by an icy waterfall; ended up with no brain damage because when she had the loss of oxygen her body temperature was so low that there was hardly any brain damage occuring
Organ of corti
hair cells located here - basilar membrane is on the bottom - tectorial membrane is on the top
every species system has
has a different critical period • Brain damage in children will likely heal better than in adults
ferret study: auditory cortex
has no input (b/c the fibers coming from the inferior colliculus in the left hemisphere are no longer there)
Why does making a connection increase likelihood of a neuron's survival?
has to be a used synapse for the neuron the survive; one of the things that these young immature neurons need to survive is a chemical called neurotrpic factors • neurotrophic factors
dose-response relationship
have a little alcohol, have a little variation; have more alcohol; have more variation
adults with cataracts not removed until adulthood
have even more trouble
people with brain damage may
have lost some ability totally or may be able to find it with some effort • much recovery depends on learning to make better use of the abilities that were spared
ferret study: retinal nerves...
have nowhere to go (b/c their targets in the left hemisphere, e.g. superior colliculus & primary visual cortex, have been lesioned)
fat receptors
haven't discovered in humans but have discovered in rats
hearing aids
hearing aids make sounds louder for older people but the older people still have trouble understanding speech, especially in a noisy room or if someone speaks rapidly - brain areas responsible for language comprehension have become less active • might be natural deterioration or a reaction to prolonged degradation of auditory input
less common type of stroke
hemorrhage
difference in intensity/loudness between the ears
high frequencies & sound shadows • for high frequency sounds, with a wavelength shorter than the width of the head, the head creates a sound shadow, making the sound louder for the closer ear • head filters out sound so by the time it reaches the other ear you just a sound shadow a portion of the sound hitting the other ear
parabelt region of the auditory cortex
highest level of processing
itch: some spinal cord pathways respond to...
histamine itch and others respond to cowhage itch
damaged tissue
histamine, nerve growth factor
damage or inflamed tissue releases
histamine, nerve growth factor, and other chemicals that help repair the damage but also magnify the responses of nearby heat and pain receptors
How gene expression is regulated
histones
horizontal cells run
horizontally between the bipolar cells & the photoreceptors
how far you see depends on
how far the light travels before it strikes the eyes
Pitch
how we perceive frequency • Sounds higher in frequency are higher in pitch • Pitches animals can hear often relates to size
However, what does the brain need after birth to maintain and fine-tune its connections?
however, the brain needs visual experience after birth to maintain and fine-tune it's connections
Homozygous
identical pair of genes on the two chromosomes
discriminative touch
identify shape of object
target cells
if a neuron connects with someone else, the neuron gives it neurotrophic factors; neurons exchange neurotrophic factors
lack of two eyes
if completely closed during critical period then sight will never be regained but if reopened during critical period then some sight may occur
area A1 responds to...
imagined sounds as well as real ones
stem cells
immature; vary in how much they can continue to change - totipotent cells - pluripotent cells - multipotent cells
Prosopagnosia
impaired ability to recognize faces
behavior in adolescence
impulsive, prone to seek immediate pleasure • have stronger brain responses than adults when anticipating rewards and weaker responses in the prefrontal cortex, responsible for inhibiting behavior • heightened impulsivity occurs almost exclusively in social settings
pain & touch pathways decussate
in different areas
Koniocellular information goes
in-between (ventral) the layers described above - 4A
Estradiol and taste
increases acuity to taste - Adaptive because present in pregnant woman who want to avoid illness while pregnant from things that taste/smell bad/unsafe
immature brain is also highly responsive to...
influences from mother • Stress on the mother → changes her behavior in ways that change her offspring's behavior
David Hubel and Tortsten Wiesel (1959)
inserted thin electrodes to record activity from cells in cats and monkeys' occipital cortex while they shined light patterns on the retina and found that the cells had bar-shaped receptive fields • distinguished several types of cells in the visual cortex
primary taste cortex
insula • Receives input from both sides of the tongue • Has areas that respond to one type of taste and multiple types of tastes
Amplitude
intensity (i.e. loudness); height of each wave
sometimes, bottom-up processes & top-down processes
interfere with each other
Gustatory pathway is mostly...
ipsilateral connection - anterior of tongue: 7th cranial nerve (chorda tympani) - posterior of tongue: 9th cranial nerve - throat: 10th cranial nerve
ampulla
is in the semicircular canal filled with fluid; ampulla's cilia (hairs) are embedded in the cupula (bulge in the semi-circular canal)
necrotic death
is quite sudden and cell tends to leach out everything in its gut; some of these chemicals are harmful and can cause other cells to die or to inflame and become irritated occurs during stroke (along with apoptosis); any type of sudden death
blue, etc.
is worse but more recessive genetically
most common type of stroke
ischemia
Lateral inhibition: When a bipolar cell is activated
it sends information to horizontal cells (e.g.) which will then inhibit the neighboring bipolar cells. The inhibition strength decreases, the farther away it is from the particular amacrine cell
when an olfactory receptor is stimulated
its axon carries an impulse to the olfactory bulb
After a cell loses input from an axon
its secretes neurotrophins that induce other axons to form new branches or collateral sprouts that take over the vacant synapses • can be helpful or harmful depending on whether the sprouting axon conveys info similar to those that they replace
Ganglion cell axons
join together to form the optic nerve and travel back to the brain
delay getting hearing aid
language cortex doesn't get normal input and becomes less responsive
receptive fields LGN cells
larger co-centric receptive fields
receptive fields simple cells
larger, rectangular, fixed excitatory/inhibitory zones
End-stopped or hypercomplex cells Size of receptive field
largest
LGN info enters through
layer 4 and stays separate • remember that there are 6 layers in most areas of the cerebral cortex • parvocellular info goes into 4Cβ • koniocellular info goes into 4A • magnocellular info goes into 4Cα
other neurons
lazy neurons; not pioneers, just followers • fasciculation - following the chemical trail of the pioneer neurons
effects of a stroke: Impair the sodium-potassium pump
leading to an accumulation of sodium inside neurons
chronic pain
leads to depression and decreased activity in the prefrontal cortex - a barrage of painful stimuli potentiates its synaptic receptors so that they respond more vigorously to the same input in the future • the brain learns how to feel pain, and gets better at it
things in right visual field are seen by
left side of brain
sound localization is...
less accurate than visual localization
In adult humans, taste buds...
lie along the edge of the tongue - often on the sides, but not in middle/top usually • tongue creates an illusion of taste all over the tongue by extrapolating tastes detected on side of tongue to the middle which saves body resources by not having to make as many taste receptors
you see something only when
light from it strikes your eyes and alters your brain activity
Route Within the Retina
light passes through the ganglion, amacrine, bipolar cells, and horizontal cells en route to the photoreceptors • then transduction occurs
Vitreous humor
light passes through this fluid and then hits the retina
ON center cells increase their activity when
light shines on the center, while decreasing their activity when light shines in the surrounding OFF area
The pathway of light through the eye
light → cornea → aqueous chamber → pupil/iris → lens/ciliary muscle and ligaments → vitreous humor → retina
Offspring generally resemble their parents for genetic reasons
like begets like
to prevent chronic pain,
limit it from the start - i.e. start taking morphine before the surgery and you need less of it afterward
in V2, many cells still respond best to
lines, edges, and sine waves but some cells respond selectively to circles, right angles, and other complex patters and texture
axons carrying pain info have...
little or no myelin so they conduct impulses relatively slowly but brain processes them more rapidly • thicker, faster axons convey sharp pain • thinner ones convey dull pain
anatomy & physiology of the vestibular system
located in the inner ear next to the cochlea • semicircular canals - three • vestibular sacs - two
humans proliferate...
longer than chimpanzees • Nearly all neurons form within the first 28 weeks of gestation → premature birth before that time inhibits neuron formation
for the hemi-nasal retinal areas
look at the edges of the visual fields; see SAME far side as eye but info is processed in OPPOSITE side of the brain • Notice that the neurons in the hemi-nasal retinal areas send their information to the opposite side of the brain. This is referred to as a contralateral connection
for the temporal-hemi retinal areas
look at the middle of the visual fields; sees OPPOSITE SIDE as eye but info is processed on SAME side - right eye sees from the middle to the mid left so the right side of the brain processes (almost) all left info - left eye sees from the middle to the mid right so the left side of the brain processes (almost) all right info • Notice that the neurons in the temporal-hemi retinal areas send their information to the same side of the brain. This is referred to as an ipsilateral connection. • Overlap between what the eyes see
Aguesia
losing ability to taste - Rare because there are 3 nerves related to taste and so many brain areas involved in taste
Damage to V4
loss of color constancy and/or visual attention
necrosis during stroke
loss of oxygen (& glucose) • impaired Na+ - K+ pump → increased Na+ inside of neuron • increased glutamate (excitatory) → overstimulation of the neuron • blocks mitochondrial metabolism • neuronal death • glial proliferation → scar tissue?
phase difference between the ears
low frequency sounds • ever sound wave has phases with consecutive peaks 360 degrees apart • how much out of phase depends on the frequency of the sound, the size of the head, and the direction of the sound • localize low-frequencies
magnocellular information goes to
lower layers (2 -1) - 4Cα
totipotent cells
make up ball - can become part of anything (embryo, supporting structures of embryo) - w/in 36 hours, the zygote multiplies into many cells
Growing up in constant noise...
makes it harder to identify and learn about individual sounds causing impairments in auditory development
scratched cornea
makes vision blurry because cornea is no longer completely transparent; painful - must just wait for eye to fix itself
in a newborn mammal
many of the normal properties of the visual system develop normally at first, before birth • waves of spontaneous activity sweep over developing retinas, synchronizing activity among neighboring receptors and enabling appropriate combos of receptors to establish connections with cells in the brain
taste transduction: bitter
many varieties of T2R • (so, I'm just pointing out here that the same family of receptors are involved: but the pattern of receptor activation determines the taste, e.g., whether sweet or bitter)
neuronal death/apoptosis in the prefrontal cortex
matures later than college; brains don't work as well until this part is completely mature which involves death of neurons - coordinates thoughts & actions, including: • working memory, attention, planning & carrying out sequences of actions, inhibiting inappropriate actions (impulse control), higher order thinking - does not mature until the late teens (~18 yrs. of age)
viral brain infections
may be less aggressive than bacterial but we don't have many anti-viral medications - e.g., rabies (virus) - e.g., Herpes (virus)
all these different migration theories...
may be valid depending on which area of the brain and which neurons we are referring to.
chemical sense...
may have been the first sensory system of the earliest animals
can test new neuron formation in humans by...
measuring the radioactive isotope of carbon 14C whose concentration in the atmosphere compared to other isotopes of carbon was almost constant over time until the era of nuclear bomb testing released a lot of radioactivity; now declining again • Found that skin cells reflect the 14C concentration of the current year, meaning they are replaced quickly • Muscle cells reflect the 14C concentration of 15 years ago so they're replaced slowly • Heart cells have 14C concentrations reflective of the persons birth year, meaning the body replaces no more than 1% of hear cells • Neurons and olfactory bulbs in humans also have 14C concentrations of the persons birth year o Means no new neurons are formed in the cerebral cortex under normal circumstances • Humans replace ~2% of hippocampal neurons per year
high frequency sounds are more...
medial & posterior
Complex Cell Size of receptive field
medium
men and menstruation
men can identify menstrual stage by smell at better than chance levels
blueprint hypothesis analogy
men lining up in order of tallest to shortest then pairing up with women who lined up tallest to shortest
Gender differences in casual sex
men want it more because more sex means a higher chance of propagating their sperm and increasing the spread of their genes whereas this is not the case for women
exposure to cannabinoids during stroke...
minimizes damage by decreasing the release of glutamate and are anti-inflammatory - only effective within the first hour - anti-oxidant and anti-inflammatory properties? - Also causes suppression of excitatory activity; but the problem is first stimulates then decreases
current theory of pitch
modification of both theories
Hermann von Helmholtz
modified Young's theory to the trichromatic or Young-Helmholtz theory of color • Trichromatic Theory
even traits with high heritability can be
modified by environmental interventions
Merkel's disks
modified dendrite - located in Both hairy and hairless skin - responds to Light touch
Toward the periphery of the retina
more and more receptors converge onto bipolar and ganglion cells • as such, the brain cannot detect the exact location or shape of a peripheral light source • However, the summation enables perception of fainter lights in the periphery
cells in the MST respond best to
more complex stimuli such as expansion, contraction, or rotation
lack of one eye
more damaging because the one eye that was open took all the synapses it could so once the other eye of the cat was opened there was nothing for the second eye to connect to
enriched environment
more gray matter than in an impoverished environment
Distribution of receptors: glaborous skin
more number and variety of receptors - free nerve endings, Ruffini corpuscles, Pacinian corpuscles, Meissner's corpuscles, Merkel's discs
women detect odors...
more readily than men and brains responses to odor are stronger in women than in men • ↑ sensitization with practice & female hormones
opiates bind to receptors founds...
mostly in the spinal cord and the periaqueductal gray area of the midbrain
Dorsal stream receives
mostly magnocellular input = integration of form & movement
MT (aka V5)
motion of objects or still photographs implying motion
migration
movement of neurons; very rapid - Some neurons migrate faster than others; some don't reach destination until adulthood
radial migration
moving outward from the middle of the neural tube
Stronger support when
multiple kinds of evidence support it • Loneliness, neuroticism, television watching, childhood misbehavior, social attitudes, cognitive performance, educational attainment, and speed of learning a second language all have evidence of significant heritability • Religious affiliation has NOT shown a significant heritability
diversity of olfactory receptors makes possible...
narrow specialization of functions
any behavior characteristic of a species arose through
natural selection and presumably provided some advantage • Ex → some animals have better color vision/peripheral vision; some animals sleep less because they may be attacked at night
When light hits all of on center cell
near basal level activity because the on center and off ring cancel each other out
chemicals of similar smells excite
neighboring areas and chemicals of different smell excite separated areas
opiates act on...
nervous system rather than injured tissue
neuronal death during stroke is due to
neuronal death during stroke is due to: • necrosis → bad, unexpected • apoptosis → programmed cell death
olfactory cells
neurons responsible for smell that line the olfactory epithelium in the rear of the nasal air passages - each olfactory cell has cilia that extend from the cell body into the mucous surface of the nasal passage • olfactory receptors are located on the cilia
feature detectors
neurons whose responses indicate the presence of a particular feature
proliferation in the adult brain
new neurons in the olfactory bulb/system and hippocampus during adulthood - physical and mental exercise and happiness increase new neurons (found in rat studies) in these areas - more positive means being more creative • people perform better on tests when they're happy
Color sensitivity of Magnocellular Neurons
no
if neither eye is active
no axon outcompetes any other • for 3 weeks, the cortex remains responsive to visual input • longer than that, cortical responses start to become sluggish and lose their well-defined receptive fields • eventually, the visual cortex starts responding to auditory and touch stimuli instead
people with damage to area V1 report
no conscious vision, no visual imagery, and no visual images in their dreams
Weaknesses of the trichromatic color theory
no explanations for: - negative color afterimage (aka complementary afterimage) • color afterimage → see opposite color after looking at something long enough then looking away - mixed colors → i.e. reddish-green or bluish-yellow - primary colors → not made up of anything else • most people think yellow is primary but then why is there not a cone for yellow
Spinothalamic tract
nociceptors → spinal cord → ventral posterior nucleus (thalamus) → somatosensory cortex
Altruism is harder to find among
nonhumans although they do cooperate together (i.e. hunting, sharing food) - Monkeys and two ropes with food for one or food for two → monkeys pull whichever rope is on the right, suggesting right-handedness but not altruism
which pathway does normal behavior use
normal behavior makes use of both pathways/streams in collaboration and damage to either pathway affects all tasks to some degree and others more than others
mature brain
notice how the forebrain has grown so much that it now sits on top of the midbrain and hindbrain
Neurotropic factors
nurturing; help immature neuron to stay alive; suppresses apoptosis (cell suicide); without these, apoptosis will occur - e.g., neurotrophins such as nerve growth factor, brain-dervived neurotrophic fact (BDNF) (there are many others)
for what types of sounds do phase differences not work?
o does not work for high frequency sounds because the high frequency sine waves are very close together/compact for high frequency sounds, its hard to differentiate different phases because they're so tightly packed and may go through several more revolutions before it hits the other ear but its still in the same place on the sine wave
substance p and pain
often combined with glutamate to transmit high pain
olfactory receptors
olfactory cells
Olfactory pathway
olfactory cilia → thru cribiform plate → olfactory bulb
specific anosmia
olfactory dysfunction (~5%) → loss of certain types of smells
2. neurons
on the two sides of the cut pull apart
asymmetrical division
one cell becomes an immature neuron, another becomes a stem cell; division of a founder cell that gives rise to another founder cell and a neuron which migrates away from the founder to its final location in the brain • we are here longer than chimpanzees
synesthesia hypothesis
one hypothesis is that axons from one cortical area branch into another cortical area
scala tympani
one of the perilymph-filled cavities in the inner ear of the human. It is separated from the cochlear duct by the basilar membrane • transduces the movement of air that causes the tympanic membrane and the ossicles to vibrate, to movement of liquid and the basilar membrane.
the pain sensitive cells in the spinal cord relay information to several sites in the brain
one path extends to the ventral posterior nucleus of the thalamus then to the somatosensory cortex which responds to painful stimuli, memories of painful stimuli, and signals that warn impending pain
deafferentiation stroke
one treatment for stroke is to make people unable to use the normal limb so they have to use the weaker one
each olfactory receptor responds to...
only a few stimuli • combined activity of receptors identifies a chemical precisely
What gives rise to the receptive fields?
onvergence of information gives rise to the receptive fields
Place theory: the very highest frequencies of sound...
particularly stimulate the neurons which are nearest the beginning of the basilar membrane (so the base of the basilar membrane)
receptor potentials...
open voltage gated calcium channels; calcium ions then enter the cell and trigger the release of neurotransmitters at the basal end of the cell. The neurotransmitters diffuse across the narrow space between the hair cell and a nerve terminal, where they then bind to receptors and thus trigger action potentials in the nerve - convert mechanical sound signal into an electrical nerve signal
Stimulation of a touch receptor
opens sodium channels in the axon, thereby starting an action potential
What kind of receptive field do simple cells have
opponent fashion receptive field
The two optic nerves meet at the
optic chiasm where half of the axons from each eye cross over to the opposite side of the brain
three semicircular canals
oriented in perpendicular plans and filled with a jellylike substance are lined with hair cells - otolith
"top-down" processing
other brain areas interpret the visual stimulus and send messages back to reorganize the activity in the primary visual cortex • we are pre-wired to see objects as a whole (we do not necessarily build up an object in our minds from the basic features to the whole object)
the lateral geniculate sends axons to
other parts of the thalamus and the visual cortex
Brain evolved skill
our brains have evolved the ability to remodel themselves in response to experience
parvocellular information goes to
outer layers (6- 3) of LGN - 4Cβ
fovea representation in area V1
overrepresented in area V1 (25%)
nociceptors
pain
hippocampus and pain
pain memory
spinal paths for pain and touch are...
parallel, but the pain pathway crosses immediately from receptors on one side of the body to a tract ascending the contralateral side of the spinal cord - touch info travels up the ipsilateral side of the spinal cord to the medulla where is crosses to the contralateral side - so pain and touch reach neighboring sites in the cerebral cortex
cingulate cortex and pain
part of limbic system that remembers emotions • decrease negative emotional reaction to pain to decrease chronic pain
Primary Visual Cortex (area V1; striate cortex)
part of the occipital cortex; main brain area for vision
Most ganglion cell axons go to the
part of the thalamus (LGN) • A smaller number go to the superior colliculus and other areas
area V4
particularly important for color
Certain individuals reproduce more than others do, thus
passing on their genes to the next generation. Any gene that is associated with great reproductive success will become more prevalent in later generations. That is, the current generation of any species resembles the individuals who reproduced in the past. If the environment changes such that a different gene increases the probability of survival and reproduction, that gene will spread in the population
Helmholtz decided three kinds of cones because
people could match any color by mixing appropriate amounts of just three wavelengths • Short (blue), medium (green), and long (red) wavelength cone types
chemical pathfinding by axons
people often believe the nervous system to work like the prevailing technology of the time
Supertasters
people that are highly sensitive to all tastes and mouth sensations • Differences depend on the number of fungiform papillae near the tip of the tongue; supertasters have most • Women's taste levels change with cycles and are highest during early pregnancy
People who report synesthesia
people who report synesthesia have increased amounts of gray matter in certain brain areas and altered connections to other areas
other species may
perceive electromagnetic radiation in different ranges • meaning other species may perceive infrared radiation, UV radiation, etc.
orientation & location preference of complex cells
perceptive to line moving across the field in a particular direction
Sound waves
periodic compressions of air, water, or other media that vary in amplitude and frequency • Condensing & rarefying of molecules (in varying mediums) • 15 to 20,000 Hertz (cycles per second)
Mach bands
phenomenon resulting from lateral inhibition
where do pheromone receptors appear to be located in humans?
pheromone receptors appear to be located in olfactory mucosa for humans (so olfactory receptors)
hurt feelings do resemble...
physical pain in important regards → activate cingulate cortex • can be relieved with tylenol
frequency theory: the basilar membrane...
physically mimics the soundwave; some neurons at one end of the basilar membrane fire in rhythm with the physical waves (e.g., at every peak of the wave, for example) - actually a difficult process because many soundwaves have to be mimicked at once - only works up to a certain Hz
Artificial selection
plant and animal breeders choose individuals with a desired trait and make them the parent of the next generation
visual expertise depends on
practice
orientation & location preference of simple cells
prefers line stimuli in dead center of receptive field
Mechanical senses respond to
pressure, bending, or other distortions of a receptor
each eye sees
pretty much what the other eye sees, though from a different perspective. This figure is a bit misleading in that it looks as though each eye sees exactly what the other eye sees, but this is not the case. The right eye cannot see the extreme left and the left eye cannot see the extreme right (because your nose is in the way).
Magnocellular neurons
primate ganglion cells with larger cell bodies and receptive fields that are distributed evenly throughout the retina • larger cell bodies • larger receptive fields but not better • evenly throughout retina • processing movement info and overall contrast • to LGN, other thalamic areas • movement • overall patterns (very sensitive to contrast between light & dark)
Parvocellular (midget) neurons
primate ganglion cells with small cell bodies and small receptive fields located mostly in or near the fovea • smaller cell bodies • small receptive fields; detailed vision • in or near fovea • only send info to the LGN • visual details • color (red, green)
Koniocellular neurons
primate ganglion cells with small cell bodies but they occur throughout the retina; granular appearance • small cell bodies • granular appearance • throughout retina • varies (somatosensory-propioception? Color [blue]) • to various areas 9eg.g. LGN, other thalamic areas, superior colliculi
what kind of romantic partners do we prefer?
probably prefer romantic partners that smell differently from you or your family members • reduces inbreeding • increases variety of immunities in children because chemicals from the immune system contribute to body odors
Prolonged experience of a particular type...
profoundly enhances the brain's ability to perform the same function again, especially if training begins early in life
processes in the development of neurons
proliferation, migration, differentiation, myelination, and synaptogenesis
Thomas Young (1773-1829)
proposed that we perceive color by comparing the responses across a few types of receptors, each of which is sensitive to a different range of wavelengths
Edward Land
proposed the retinex theory
Cornea
protective, non-adjustable outer layer of the eye that bends light into the pupil
histones
proteins that bind DNA into a shape that is more like string wound around a ball - These molecules have loose ends to which certain chemical groups can attach - To activate a gene, the DNA must partially unwind from the histones
evolutionary psychology
psychology concerned with how behaviors evolved with emphasis on evolutionary and functional explanations (that is, the presumed genes of our ancestors and why natural selection might have favored genes that promote certain behaviors)
glia-mediated migration
radial glia cells spanning from the inner portion of the neural tube to the outer portion of the neural tube that cells crawl on
Goose bumps in humans
raise our hairs when we are cold or frightened; in other animals make fur more insulating or make them look larger/more intimidating; leftover in humans
anosmia
rare (~1%) • Zycam up nose → some felt a burning sensation then lost smell
what occurs with sound localization with age?
recalibration occurs as you age because your head grows
Cells of the lateral geniculate nucleus have
receptive fields that resemble those of the ganglion cells (an excitatory or inhibitory central portion and a surrounding ring with the opposite effect)
Instead, the influx of positive ions from the endolymph in the scala media depolarizes the cell, resulting in a
receptor potential
Touch pathway
receptors → dorsal column of white matter → decussates at the level of the medulla → ventral posterior nuclei of thalamus → primary somatosensory cortex • 2 deep pressure, kinesthesia • 2 light touch on skin • there are more maps of the body (than what is mentioned above) • → secondary somatosensory cortex, etc.
Melzack & Wall's Gate Control Theory
receptors all over our body can detect pain - gates in spinal cord but predominately in layers 1 and 2 of the dorsal horn • gate in the spine can close to stop pain when it needs to be
taste transduction: sweetness and bitterness
receptors linked to gustducin (G protein) → activates phosphodiesterase → ↓ cAMP → closing of K+ channels, action potential
connections in the visual cortex are
reciprocal • V1 sends info to V2 and V2 returns info to V1 • From V2 the information branches out in several directions for specialized processing
most common type of color deficiency
red-green colorblindness • occurs when long and medium wavelength cones have the same photopigment instead of different ones • more men (8%) are red-green colorblind than women (1%) because it occurs on the X chromosome so men need only one affected chromosome to have the deficiency
cross-adaptation
reduced response to one taste after exposure to another - toothpaste and oj?
cooling the brain during stroke...
reduces overstimulation, apoptosis, and inflammation - theoretical - slows down bodily activity → problem with stroke is overstimulation, so if we can slow down bodily activity in theory that seems like a good idea - have not yet figured out a way to cool people down low enough to help with stroke without killing people → hypothermia is worse than stroke
effects of a stroke: Combo of edema and excess sodium
release glutamate which overstimulates neurons damaging both neurons and synapses • Microglia proliferate to help this
dendritic branching mouse study
researchers injected a dye into a living mouse neuron and watched the dendritic spines extend and retract/disappear - 6% of dendritic spines appear or disappear within a month - the gain or loss of spines means a turnover of synapses which relates to learning
Pacinian corpuscles respond to
respond to Sudden displacement of skin; high frequency vibration bends the membrane enabling sodium ions to enter, depolarizing the membrane
cells in the inferior temporal cortex
respond to meaningful objects; respond according to what the viewer perceives not what the stimulus is physically
MSTd (aka dorsal MST)
responds to expansion, contraction, or rotation of visual scene
things in left visual field are seen by
right side of brain
what is risked during stroke if neuronal activity is allowed to continuing decreasing?
risking Diaschisis if activity continues to decrease; really want existing synapses to be active
two types of photoreceptors in vertebrate retina
rods and cones
genes influence behavior in
roundabout ways • Beautiful people are smiled at more → affects their personality • Very tall people are good at basketball early in life → may spend all time perfecting basketball skill
two modes of traveling in migration
somal translocation and glia-mediated migration
the primary visual cortex (V1) sends information to the
secondary visual cortex (V2)
folic acid
seems to prevent neural tube defects such as spina bifida; greatly reduces chances of neural tube defects • Prenatal vitamins - folic acid, calcium (pregnancy will suck calcium out of the female bones if there isn't enough in the body)
Kin selection
selection for a gene that benefits the individual's relatives • A gene spreads it if causes you to risk your life to protect your children, who share many of your genes, perhaps including a gene for altruism • In humans and nonhumans helpful behavior is more common toward relatives than nonrelated individuals
Most cells in MT respond
selectively when something moves at a particular speed in a particular direction • acceleration, speed • central to the experience of seeing motion
disconnect between
sensation and perception
Olfaction
sense of smell; the response to chemicals that contact the membranes inside the nose
Auditory where pathway
sensitive to sound location in the posterior temporal cortex and the parietal cortex
Auditory what pathway
sensitive to the pattern of sound in the anterior temporal cortex
strong, repeated stimulation
sensitization (potentiation)
The amount of response (how many action potentials a neurons sends per unit of time) affects
sensory coding/perception
messenger RNA
serves as a template for the synthesis of protein molecules
motion perception is set up to
set up to occur quickly and efficiently
humans likely have...
several hundred olfactory receptor proteins • rats have thousands
adult men react to sweaty women as...
sex signals
neurons differ in...
shape and chemistry
Where do simple cells converge their information
simple cells converge onto fewer complex cells; simple V1 neurons converge their data onto one complex V1 neuron • complex cells also have slightly larger receptive fields now
V1 cells
simple, complex, hypercomplex
Types of cells (feature detectors) in area V1
simple, complex, hypercomplex cells
Overall, the receptive fields of the ganglion cells are
slightly larger than that of the bipolar cells
endogenous opioids
slower pain; released naturally in body for any reasons • endorphins (e.g., beta-endorphins) • enkephalins e.g., met-enkephalin & leu-enkephalin • dynorphins • (nociceptin) • (endomorphin) • inescapable pain, sex, thrilling music, acupuncture, copulation, placebo (but NOT hypnosis)
Midget Ganglion Cells
small ganglion cells in the fovea of humans and other primates that responds to just a single cone resulting in each cone in the fovea having a single route to the brain • Provide 70% of the input to the brain → vision is dominated by what we see in the fovea
Simple cells Size of receptive field
smallest
what does olfaction play an important role in
social behavior
sodium taste receptors detect...
sodium in the food we eat and allows it to cross its membrane
somal translocation
soma with a weird appendage (like a sticky hand) throws itself out and drags itself over then repeats to continue moving - appendage is NOT always axon but can be
some individual differences in olfaction...
some due to genetic variation - common form of OR7D4 → androstenone smells like sweat or urine - less common form of OR7D4 → androstenone smells sweet or like flowers
Deterioration in Old age
some people have more genes that keep them healthy and alert at ages 85 and beyond but not everyone has these genes; may be because once we can no longer reproduce living is not advantageous (i.e. some fish/turtles who reproduce forever do not seem to age)
Diaschisis
something is not performing optimally because they're not having the same connections that they did before • Surviving neurons only function best when they're connected to other neurons • When connections are cut by cell death, the other neurons become weakened
Heritability is
specific to the population at a particular time
Some proposed evolutionary explanations are
speculative and controversial • Gender differences in casual sex • Deterioration in Old age
Gate Theory
spinal cord neurons that receive messages fro pain receptors also receive input from touch receptors and from axons descending from the brain - These other inputs can close the "gates" for the pain messages partly by releasing endorphins
chemical gradients...
steer axons that reach their targets to approximately their correct locations but not always with perfect accuracy - Each axon forms synapses onto many cells in approximately the correct location and each target cells receives synapses from many axons - Over time, each postsynaptic cell strengthens the most appropriate synapses and eliminates other • Adjustment depends on the pattern of input from incoming axons
founder cells
stem cells?; cells that divide and give rise to cells of the nervous system • inside-out growth of cerebral cortex (inner layers formed before outer layers)
those with physical eye damage
still dream and have visual imagery
damage to cingulate cortex
still feel pain but it no longer distresses them
why is tPA still most commonly used
still use because the vast majority of strokes are ischemic → can't waste time testing the type of stroke
Menthol
stimulates cool receptors
Opioid mechanisms
systems that respond to opiate drugs and similar chemicals to stop prolonged pain that is unnecessary after pain alerts you to danger
recovered behaviors that seem normal in those with brain damage are actually
taking extra effort • these behaviors decline more than in undamaged people when influenced by alcohol, physical exhaustion, or other kinds of stress that would minimally affect others • deteriorates with old age • learned behavior/compensation is effortful • alcohol • physical exhaustion • stress • age
two direction of travel in migration
tangential and radial migration or a combination of the two
taste receptors
taste buds are not true neurons but modified skin cells - have excitable membranes and release neurotransmitters to excite neighboring neurons which in turn transmit info to the brain - gradually sloughed off and replaced like skin cells • last for 10-14 days - different receptors for different tastes
variations in taste sensitivity
taste sensitivity varies among animal species and human individuals
PTC and PROP
tasters and nontasters are genetic
Taste is useful for...
telling us whether to swallow something or spit it out • like sweet and salty; dislike sour and bitter
thermoceptors
temperature
core region of auditory cortex
temporal cortex
~50 cilia per taste bud...
that have taste receptors on them and are enervated by taste nerves
3. the glial cells...
that react to CNS damage (Oligodendrocytes) release chemicals that inhibit axon growth
inconsistency of negative color afterimage among people suggests...
that the afterimage depends on the whole context, not just the light on individual receptors and that the cerebral cortex must be responsible not the bipolar or ganglion cells
Dorsal stream
the "how" pathway for vision that goes through the parietal cortex and is important for visually guided movements; this pathway stretches from the primary visual cortex (V1) in the occipital lobe forward into the parietal lobe • involved in spatial awareness and guidance of actions • parietal cortex
Ventral stream
the "what" pathway for vision that goes through the temporal cortex specializing in identifying and recognizing objects • associated with object recognition and form representation • Inferior temporal cortex • V4 • MT (aka V5) • MSTd (aka dorsal MST) • ventral MST
absolute pitch
the ability to hear a note and identify it • genetically predisposed but also increased with early music training • more common among people who speak tonal languages like Chinese
Information from the nasal half of each eye crosses to
the contralateral hemisphere
the responses of cells in V4 correspond to
the apparent or perceived color of an object which depends on total context
Volley Principle
the auditory nerve as a whole produces volleys of impulses for sounds up to about 4000 per second with individual nerves producing patterns of action potentials that summate to equal the sound wave (~300 - 4000 Hz)
hair cells
the auditory receptors that lie between the basilar membrane of the cochlea on one side and the tectorial membrane on the other - Vibrations of the hair cells caused by vibrations in the cochlear fluid excite the auditory nerve
place theoryr
the basilar membrane resembles the strings of a piano with each area along the membrane tuned to a specific frequency (~4000+ Hz) • each frequency activates the hair cells at only one place along the basilar membrane and the nervous system distinguishes among frequencies based on which neurons respond • the basilar membrane can only physically vibrate so much
Frequency theory
the basilar membrane vibrates in synchrony with a sound, causing auditory nerve axons to produce action potentials at the same frequency; analysis of the lower frequencies of sound (~15 - 400 Hz)
the point at which the optic nerve leaves the eye through the optic disk is
the blind spot because it has no receptors
info from the receptors in the anterior two-thirds of the tongue travels to...
the brain along the chorda tympani
External Auditory Canal
the canal that funnels sound waves from the pinna to the middle ear
Experience and dendritic branching
the central structure of a dendrite becomes stable by adolescence, but the peripheral branches of a dendrite remain flexible throughout life
Info from the touch receptors in the head enters the CNS through
the cranial nerves
the vestibular system detects
the direction of tilt and the amount of acceleration of the head
Retinal Disparity
the discrepancy between what the left and right eyes see; problem with binocular cues • Experience fine-tunes binocular vision and abnormal experience disrupts it
the human central nervous system begins to form when ...
the embryo is about 2 weeks old
Synesthesia
the experience some people have in which stimulation of one sense evokes a perception of that sense and another also - clusters in families frequently who also have absolute pitch
Heritability
the extent to which the variations in some characteristic depend on genetic differences (can be high or low)
Pinna
the familiar structure of flesh and cartilage attached to each side of the head • Helps us locate the source of sound by altering the reflections of sound waves
Synaptogenesis
the formation of synapses - Begins before birth, continues throughout life - Slows in older people as does the formation of new dendritic branches - throughout life (even though there is a huge amount of it prenatally as well as a few to several years after birth; there is also another surge of synaptogenesis during the early teenage years. Be sure not to mix up the terms "neurogenesis" with "synaptogenesis.") - connecting is important for a neuron's survival.
In the trichromatic theory the perception depends on the
the frequency of response in one cell relative to the frequency of another cell → we discriminate among wavelengths by the ratio of activity across the types of cones
evolution benefits
the genes of the species NOT the individuals
Sex-linked genes
the genes on the sex chromosomes (X and Y) • Female chromosomes → two X • Male chromosomes → one X, one Y
Reciprocal Altruism
the idea that individuals help those who will return the favor • People are more likely to help people who helped them previously or who they observed helping someone else • Requires an ability to identify individuals and remember them later - Humans are excellent at recognizing one another even after long delays
Viscera
the internal organs in the main cavities of the body, especially those in the abdomen • Mechanoreceptors • Chemoreceptors
Information from the temporal half of each eye goes to
the ipsilateral hemisphere
color of an object depends on
the light reflected from that object and how it compares with objects around it
Sweetness, bitterness, and umami receptors resemble...
the metabotropic synapses • molecule binds to one of these receptors, activating a G protein that releases a second messenger within the cell • each of these receptors releases ATP
endorphins
the nervous systems opiate-type chemicals that attach to the same receptors as morphine - Brain produces several types which relieve different types of pain - Inescapable pain stimulates endorphins and inhibits further pain - Also release during sex and when listening to good music
Place theory: when the particular frequency of sound is detected...
the neurons who have this preference will be most active, as compared with the other neurons on the basilar membrane
Frequency
the number of compressions per second, measured in Hz; number of waves per second - Pitch
fitness
the number of copies of one's genes that endure in later generations • Any gene that spreads is fit but these genes may turn out to be disadvantageous after a change in the environment meaning they may not be adaptive in the future so evolution does NOT always mean improvement
olfactory bulb sends axons to
the olfactory area of the cerebral cortex
The axon of the ganglion cells form
the optic nerve which leaves the retina and travels along the lower surface of the brain
Order of bases on RNA determines
the order of amino acids that compose a protein
receptive field of a rod or cone
the point in space from which light strikes the cell; the tiny portion of the visual field that the neuron can detect visual stimuli in
receptive field of bipolar and ganglion cells
the points in space from which light strikes the cells from which these cells receive connections; the sum of the receptive fields of their connected cells
Overall destination for auditory info is
the primary auditory cortex (area A1) in the superior temporal cortex
differentiation
the process by which a primitive neuron forms in axons and dendrites so that it becomes different from other neurons - Axons grow first and are often towed like tails during migration and point toward their target - Dendrites are formed when the neuron reaches its target - axonal, then dendritic growth • sometimes while migrating • axon grows towards target
myelination
the process by which glia produce the insulating fatty sheaths that accelerate transmission in many vertebrate axons - Forms first in the spinal cord then in the hindbrain, midbrain, and forebrain - Continues gradually through adolescence and adulthood - Vulnerable process → social isolation impair myelination - throughout life - myelination occurs from hindbrain to forebrain - it is a rough index of brain maturation; with myelination, the brain functions better
certain types of brain damage lead to...
the production of new neurons in the cerebral cortex of rodents • persisted for at least a year, but failed to differentiate, leading researchers to be unsure of purpose
Immature neurons experimentally transplanted from one part of the developing cortex to another develop...
the properties characteristic of their new location - neurons transplanted at a slightly later stage develop some new characteristics but keep some old • analogy → like the speech of immigrant children
messages go from
the receptors at the back of the eye back to through the horizontal cells to the bipolar cells
Problem with the frequency theory
the refractory period of a neuron is 1/1000 second, so the maximum firing rate of a neuron in this theory is about 1000 Hz, far short of the highest frequencies we hear
hemorrhage
the result of a ruptured artery • Neurons are flooded with blood and excess oxygen, calcium, and other chemicals • occurs when blood vessel system becomes weak in one area and explodes • may be genetic issue • really bad because its hard to fix esp. the farther interior it is
painful stimuli also activate a path that goes through
the reticular formation of the medulla and then to several of the central nuclei of the thalamus, the amygdala, hippocampus, prefrontal cortex, and cingulate cortex • react NOT to the sensation but to its emotional associations
Lateral inhibition
the retina's way of sharpening contrasts to emphasize borders of objects; the reduction of activity in one neuron by activity in neighboring neurons
neural tube
the start of the nervous system - The dorsal surface thickens - Long thin lips rise, curl, and merge to form the neural tube, which surrounds a fluid-filled cavity - As it sinks under the skin, the top part enlarges and differentiates into the hindbrain, midbrain, and forebrain - The rest becomes the spinal cord - The fluid filled cavity becomes the central canal of the spinal cord and the 4 ventricles of the brain with cerebrospinal fluid
ability to recognize faces correlates strongly with
the strength of connections between the occipital face area and the fusiform gyrus • Prosopagnosia
when just one eye is open in a kitten
the synapses from the open eye inhibit the synapses from the closed eye
A strand of DNA serves as a template for
the synthesis of ribonucleic acid (RNA) molecules, a single strand chemical
Somatosensory system
the system that detects the sensations of the body and its movements
the visual cortex returns many axons to
the thalamus • the thalamus and cortex are constantly feeding information back and forth
When you move your head,
the vestibular organ adjacent to the cochlea → monitors movement and directs compensatory movements of your eyes • head moves left, eyes move right; head moves right eyes move left to keep your eyes focused on what you want to see
current theory: as sounds exceed 100 Hz
the volley principle
if a kitten wears goggles with horizontal lines on them in its early sensitive period,
then nearly all its visual cortex cells become responsive only to horizontal lines • Astigmatism
endomorphin
theoretical; think its an opiate but unsure
When the cilia of a bundle are undisturbed
there is little tension on their insertional plaques by the tip links, so the ion channels are mostly closed, but not completely. Small amounts of K+ and Ca2+ flow in through the ion channel.
When the cilia in a bundle are bent towards the longest cilium - either by direct physical contact with the overlying moving tectorial membrane (outer auditory hair cells) or by the motion of fluid (inner auditory hair cells)
there is much tension on the insertional plaques by the stretching tip links, which leads to the opening of the ion channels. Thus, a lot of K+ and Ca2+ flow in and cause a depolarization of the membrane.
When the cilia in a bundle are bent towards the shortest cilium,
there is no tension on the tip links or insertional plaques so all of the ion channels are completely closed. Therefore, no K+ or Ca2+ flow in and the membrane becomes hyperpolarized.
Even when animals appear altruistic
they have a selfish motive • Crow finds food on the ground → caws for others not to share but because they are vulnerable on the ground alone
a delta fibers
thinly myelinated nerves that carry cold, pressure, and some pain signals
nature also selects
those who are more successful than others in finding food, escaping enemies, attracting mates, or protecting their offspring will be more able to reproduce and their genes will prevail
differentiation takes...
time - meaning our brain is variable for a long time which is adaptive
in adult humans, VNO is...
tiny and vestigial → has no receptors • but part of humans olfactory mucosa contains receptors that resemble other species' pheromone receptors
ossicles
tiny bones that transmit the vibrations to the oval window and increase force - hammer (malleus), anvil (incus), and stirrup (stapes)
treatments for stroke in humans
tissue plasminogen activator (tPA)
Our ancestors managed
to get enough nutrition to provide a big brain with all the food it needs
amusia
tone deafness; cannot tell when people are singing off key and have a hard time gauging emotion from voice • can still imitate other people's pitches though they can't say whether one is higher than another • runs in families • ears likely register information but they fail to process it
how is the auditory cortex arranged?
tonotopically arranged
tonotopically arranged
tonotopy is the spatial arrangement of where sounds of different frequency are processed in the brain. - Tones close to each other in terms of frequency are represented in topologically neighbouring regions in the brain.
olfactory bulb is...
topographically-organized ("olfactotopic") • receptors are randomly distributed but then organize into glomeruli bulbs
mechanical senses include
touch, pain, and other body sensations such as vestibular sensation
rats with damage to visual cortex
training can help to regain lost abilities/memories
Far transfer
training on one task and finding improvement in other tasks • weak effect • brain is not like a muscle; cannot be exercised to be bigger and stronger
near transfer
training on one task and finding improvement in similar tasks
electrical stimulation and pain
transcutaneous electrical nerve stimulation
Amacrine cells
transparent cells that get information from bipolar cells and send it to other bipolar, Amacrine, and ganglion cells • refine input to ganglion cells → enabling certain ones to respond to particular shapes, directions of movement, changes in light, color, and other visual features • amacrine cells run horizontally between the ganglion cells & bipolar cells
Bipolar cells
transparent type of neuron in the retina that receives input directly from the receptors; located closer to the center of the eye
Ganglion cells
transparent type of neuron in the retina that receives input from the bipolar cells; located closer to the center of the eye still than bipolar cells - Retina has more ganglion cells than bipolar cells
Uracil, Guanine, Guanine
tryptophan
brain damage
tumor, infection, radiation/toxin, degenerative conditions
Even when people have virtually the same genes and grow up in the same environment they can
turn out differently
Adding methyl groups (CH3)
turns genes off
Removing methyl groups
turns genes on • Ex → severe traumatic experiences in early childhood decreases methylation of many brain genes increasing later risk of depression, PTSD, etc.
Co-centric receptive field
two parts of a receptive field that cause neurons to respond differently; has a circular center with an antagonistic doughnut-shaped surrounds; excited in the center and inhibited in the surround (ON center) or the opposite (OFF center)
Retinex Theory
vision theory stating that the cortex compares information from various parts of the retina to determine the brightness and color for each area - We make inferences about things we see → visual perception requires reasoning and inference not just retinal stimulation
Cones
visual receptors abundant in and near the fovea that are less active in dim light, more useful in bright light, and essential for color vision - Cones → Color - Provides about 90% of the brain's input
Rods
visual receptors abundant in the periphery of the human retina that respond to faint light but are not useful in the daylight because bright light bleaches them - Outnumber cones 20 to 1
Saccades
voluntary eye movements • area MT and parts of the parietal cortex decrease activity during saccades → become temporarily motion blind
pheromone/VNO anatomy in animals
vomeronasal organ (VNO) - located near olfactory receptors - very few and very speciific (will hardly respond to other odors) - does NOT adapt
olfactory receptors are
vulnerable to damage because they are exposed to air
All parts of the brain make...
way too many neurons; each brain area has a period of massive cell death becoming littered with dead and dying cells - loss of less successful cells in a certain part of the brain often indicates maturation of more successful cells • Teenagers → lose cells in the prefrontal cortex while neuronal activity increases there
Because of our diet
we evolved such big brains without sacrificing other functions • Ancestors learned to cook • Hunted in groups, bringing back more food • Ate nutritional seafood
bacterial brain infections
we have antibiotics that we can use but we're becoming immune to them, esp. with age
Opponent Process Theory
we perceive color in terms of opposites; the brain has a mechanisms that perceives color on a continuum from red to green, another from yellow to blue, and another from white to black - Neuronal fatigue
Trichromatic Theory
we perceive color through the relatives rates of response by three kinds of cones, each one maximally sensitive to a different set of wavelengths; at least 3 different kinds of cones in our eyes and each different cone has different preference for wavelength
denervation supersensitivity
when a certain set of synapses becomes inactive the remaining synapses become more responsive, more easily stimulated (aka receptor Supersensitivity); when neurons are lost, function decreases so existing neurons become supersensitive to return to normal levels but sometimes they overshoot and go past normal levels • demonstrated mostly with dopamine synapses • sometimes enables people to maintain nearly normal behavior • sometimes causes chronic pain • can go from feeling numb to feeling pain because of Supersensitivity • can be good but can go awry • upregulation
Mutations recombinations, and microduplications of genes
• Mutations recombinations, and microduplications of genes introduce new heritable variations that help or harm an individual's chance of surviving and reproducing
Duplication
when during reproduction part of a chromosome that ordinarily appears once might instead appear twice
Deletion
when during reproduction part of a chromosome that ordinarily appears once might instead not appear at all
the developing nervous system faces a challenge when...
when it sends axons over great distances
illusion
when people misperceive a stimulus, the synesthetic experience corresponds to what the person though the stimulus was, not what it actually was • implies that the phenomenon occurs in the cerebral cortex, not in the receptors or their first connections to the nervous system
deafferented
when something has lost its afferent (sensory) input
what happens when women start taking birth control
when women start taking birth control, their preference for a different smelling mate decreases • may be because women who cannot become pregnant at the moment no longer face the risk of inbreeding
focal hand dystonia
when you cannot clearly feel the difference between one finger and another making it difficult to move them independently; one or more fingers may get into constant contraction - Used to treat the hand in the past - Now, give periodic bursts of vibration stimuli to various hand muscles and make musicians carefully attend to the stimuli, improving finger sensations for up to 24 hours - can develop brain so much that bran areas begin to overlap and brain becomes confused as to what it needs to do • usually people just need to back off, but sometimes brain does not go back
Calcarine fissure
where area V1 actually is
papillae
where mammalian taste receptors are on the surface of the tongue • papillae may contain 10 or more taste buds which contains 50 receptor cells - related to taste buds because taste buds are embedded on these bumps
Optic Chiasm
where the optic nerve crosses
Occipital Lobe
where the primary visual cortex is - aka V1, striate cortex, AKA primary visual cortex
Place theory: the lower of the high frequency range...
while stimulates the neurons at the apical end of the basilar membrane the most
The rods and cones of the retina make synapses
with horizontal cells and bipolar cells
pheromones and menstruation
women sync up menstrual cycles due to pheromones - mcclintock effect women cycle faster when constantly in the presence of men which increases chances of passing on genes
Complex Cell Binocular input
yes
End-stopped or hypercomplex cells Binocular input
yes
Simple cells Binocular input
yes
Animal Perspectives
• Many birds have two foveas and their eyes occupy most of the head • Many birds also have a high concentration of receptors on the top half of their retinas for constantly looking down at the ground • Many prey species like mice have more receptors in the bottom half of their retinas for looking up
if development is messed up early in life...
you're messed up
perception
your interpretation, experience of it
how long do olfactory neurons survive
~1 month survival → new one grows when lost
taste buds survive...
~10 days and are then reproduced
neural tube formed
~24 days after conception
how many olfactory receptors are there
~6 million receptors total; ~339 types of receptors
Anatomy of nose
• 1 square inch of mucous membrane up high in the nose that detects smell • cilia of olfactory bipolar neurons (part of brain) protrude through mucous
Organization of the primary visual cortex
• 6 layers (layer 1 = skull; layer 6 is deepest) • visual modules
what is the early brain highly vulnerable to?
• Brain is highly vulnerable to malnutrition, toxic chemicals, and infections that would only produce mild problems at later ages
2 triggers to close pain gates
• CNS trigger → brain registers that you should not be paying attention to pain • PNS trigger
herpes transmission
• Can pass from lips to genitals, vice versa • 60-80% of college students will get herpes
olfaction and binding problem
• Don't know how individual molecules combine to give us different smells like pizza vs. hot dog
ferret study: turns
• It turns Right—so what does this tell you about the answer to the above question? That the temporal cortex in the left hemisphere is processing this stimulus as a type of visual input NOT auditory input
A-δ fibers and pain
• Larger diameter, myelinated, faster • sharp pain (stabbed)
How does the bipolar neuron then tell the brain that it sees yellow?
• Neuron is inhibited which signals yellow
ferret study: now train
• Now train the ferret to be able to communicate with you by training it to turn left when it hears a tone - and learns to turn right when it sees a red light flashed briefly in the left visual field (stimulating the right hemisphere, which is wired normally)
Ferret Experiment: damage
• On one side of the brain, researchers damaged the superior colliculus and the occipital cortex, the two main targets for the optic nerves. On that side, they also damaged the auditory input. They left the other side intact.
Complex Cells respond to
• Responds more strongly to moving stimuli • motion detectors
Where do sex linked genes usually occur?
• Sex linked genes usually occur on the X chromosome because the Y chromosome is very small though it does influence genes on other chromosomes - Ex → red-green color blindness occurs on the X chromosome, meaning all men with the deficient X chromosome will be colorblind; women must have two deficient X chromosomes to be colorblind
Auditory pathway
• Sound enters the ear in the Pinna → travels through the external auditory canal → virbrates tympanic membrane (AKA eardrum) → ossicles (increases force; malleus, incus, stapes) pound on → oval window which virbates → cochlea (fluid-filled) → Organ of Corti (basilar membrane with hair cells & tectorial membrane; transduction occurs here) → 8th cranial nerve and round window
maturation of the vertebrate brain
• The dorsal surface thickens and then long thin lips rise, curl, and merge, forming a neural tube that surrounds a fluid-filled cavity • As the tube sinks under the surface of the skin, the forwards end enlarges and differentiates into the hindbrain, midbrain, and forebrain • The rest becomes the spinal cord • The fluid filled cavity within the neural tube becomes the central canal of the spinal cord and the four ventricles of the brain containing the CSF
Ferret experiment: result
• The ferrets turned the way they had been taught to turn when they saw something → the rewired temporal (auditory) cortex, receiving input from the optic nerve, produced visual responses
Ferret Experiment: the optic nerve
• The optic nerve could not attach to its usual target and the auditory area of the thalamus lacked its usual input • As a result, the optic nerve attached to what is usually the auditory area of the thalamus
Ferret Experiment: stimuli
• The researchers presented stimuli to the normal side of the brain and trained the ferrets to turn one direction when they heard something and the other direction when they saw a light. • Once learned well, the researchers presented a light that rewired side could see
Ferret Experiment: auditory thalamus and cortex
• What would have been the auditory thalamus and cortex reorganized, developing some (but not all) of the characteristic appearance of visual areas
things humans cannot smell
• air molecules (oxygen, nitrogen) • natural gas (we add smell to make gasoline to smell bad) • carbon monoxide
Extrastriate cortex
• aka V2 aka secondary visual cortex • responds to more complex stimuli • may play a small role in visual attention • strong feedback with V1
weight of the human brain at birth, age 1, and adulthood
• at birth, the average brain weighs 350 grams (2 1/3 apples)/.77lbs • at the end of the first year, it weights 1000 grams (2.2 lbs) • the adult brain weighs 1200-1400 grams (9 1/3 apples (2.65-3.09 lbs)
red or green opponent process
• by increasing activity, a neuron can signal that it detects red • by decreasing activity, a neuron can signal that it detects green • or vice-versa
treatments for stroke in lab animals
• decrease stimulation by blocking glutamate synapse or blocking calcium entry • cooling the brain which reduces overstimulation, apoptosis, and inflammation • exposure to cannabinoids minimizes damage by decreasing the release of glutamate and are anti-inflammatory • omega-3 fatty acids
ways to localize sound
• difference in time of arrival at the two ears • difference in intensity/loudness between the ears • phase difference between the ears
each spinal nerve
• each spinal nerve has a sensory and motor component • each spinal nerve innervates a dermatome
ex. of need to know basis
• ex → cells that help your hand muscles reach out to an object need to know the size and location but not the color; cells that help you recognize faces need to be sensitive to details of shape, but not to location
two kinds of itches
• itches causes by mild tissue damage that releases histamines that dilate blood vessels and produce an itching sensation • contact with certain plants (cowhage) produce itches
Spinomesencephalic tract
• nociceptors → spinal cord → reticular formation (medulla) → several central nuclei (thalamus) & amygdala & hippocampus & prefrontal cortex & cingulate cortex
Pain modulation pathway: CNS trigger (top down) (powerful method)
• opiates inhibit PAG interneurons • → thus disinhibiting other PAG neurons which release • →enkephalins to excite raphe nucleus (medulla) neurons to release • → 5-HT in spinal cord • → simulating spinal cord interneurons to release enkephalins which prevent the release of substance P (below is a figure which illustrates the role of the spinal interneuron)
There are several layers of the LGN
• outer layers (6- 3) • lower layers (2 -1)
face recognition depends on several brain areas including
• part of the inferior occipital cortex known as the occipital face area → parts of the face • the amygdala • parts of the temporal cortex, including the fusiform gyrus, especially in the right hemisphere → face viewed from any angle
only 3 types of objects produce specific responses
• pictures of places • faces • bodies
what methods of birth control do not work
• pull-out method • temperature tracking • calendar method
Epigenetics in humans
• when you learn something, activity in certain genes in certain cells is increased while in others it is decreased • drug addiction produced epigenetic changes • feeling socially isolated or rejected alters the activity of hundreds of genes
Visual field
→ everything you can see
Low blood glucose
→ impairs brain development in infants
Fever
→ impairs neuron proliferation in fetus
Impaired thyroid function (iodine deficiency)
→ lethargy in adults, mental retardation in infants (rare today)
additive color mixing
→ mixing light together, causes white
subtractive color mixing
→ mixing pigments together, causes black
gustatory pathways
→ nucleus of tractus solitarious (medulla) → pons • & lateral hypothalamus • & amygdala • & somatosensory cortex (tongue stimulation) • & ventral posteromedial thalamic nucleus (which also receives somatosensory information) → primary gustatory cortex (insular cortex) → secondary gustatory cortex (caudolateral orbitofrontal cortex)
auditory pathway: contralateral side
→ superior olivary (medulla) → lateral lemniscus → inferior colliculi (midbrain) →medial geniculate nucleus (thalamus) → primary auditory cortex (superior temporal lobe)
auditory pathway: ipsilateral side
→superior olivary (medulla) → inferior colliculi (midbrain) → medial geniculate nucleus → primary auditory cortex (superior temporal lobe)
