Psych 3313: quiz 4

What opens/closes the mechanically gated potassium channels?

"Tip-links". - (stereocilia movement)

what other structures are part of the limbic system

- septal area - olfactory bulbs - parahippocampal gyrus - mammillary bodies - fornix

Parvocellular (LGN layers)

- smaller cells, top (Dorsal) four layers (3-6) - receive input from the P ganglion cells - respond best to fine spatial details of stationary objects

Visual field at the level of the thalamus

- so we have letters A-F which represent the left visual field (A-C) and right visual field (D-F) - each eye perceives all of the different letters (A-F) - we cross over at the optic chiasm, by the time we get to the LGN we see that it is only the opposite/contralateral visual field - so the left LGN only has the letters from the right visual field (D-F) but this info comes from BOTH eyes - the right LGN only has the letters from the left visual field (A-C) but this info comes from BOTH eyes and is still keeping track which info came from which eye (so even though we have A-C from both eyes in the right LGN we code which A-C came from which eye) - the visual area of the cortex is where we see the A-C info from both eyes combines

Ganglion cells

- somewhat analogous to bipolar cells b/c they have the center surround receptive fields - input: bipolar cells and amacrine cells - produce action potentials (first we have talked about this) - axons of these ganglion cells flow/bundle together and forms the optic nerve and leave the eye at the optic disk blindspot - the receptive fields replicate the info passsed to them by the bipolar cells (so if we have an on center bipolar cell receptive field, then we are going to have an on center ganglion cell receptive field) - the ideal stimulus to activate a ganglion cell is going to be a dot of light of a specific size that corresponds to the receptive field (little circles of light) - they are sensitive to contrast, if there isn't change in the light they do not respond as much (imagine walking up a set of stairs without seeing where light and dark change)

Primary visual cortex alternative names? Secondary processsing areas?

- striate (striped) cortex which is distinctly layered - Brodmann's area 17 - V1 - primary visual cortex The occipital lobe has the primary visual cortex and then has secondary processing areas of the visual association cortex and the higher order visual association cortex

cingulate gyrus (limbic system)

- technically part of the cortex, is very medial/close to midline - we usually split it in 2 parts: the anterior cingulate cortex and the posterior cingulate cortex

embryological divisions

- telencephalon - diencephalon - mesencephalon - metencephalon - myelencephalon

structure of photoreceptor cells

- the OUTER segment is farthest back, this is where it gets the nutrients from the blood supply (epithelium) and this is where it stores those chemicals that are actual pigments - the INNER segment is where the pigments are made Pigments contain chromophore which is what responds to the light and a protein called an opsin (every photopigment ends with the suffix opsin which determines which wavelenth it responds to)

alcohol consuption and cerebellum

- the cerebellum's cells are vulnerable to the effects of alcohol (they have a lot of GABA-a receptors) - the "walking the line"/field sobriety task when pulled over by cops is designed as an indirect way to see how a person's cerebellum is functioning (not done too much anymore as we have breathalyzers) - another task is called a "horizontal gaze nystagmus test" where you have a flashlight and have them direct their gaze on following that objects. a sober person's eyes are going to move smoothly/fluidly while an intoxicated is going to show a nystagmus, moving in a jerky pattern

Unrolled cochlea

- the diameter is very different - the thickness of the basilar membrane is different from the starting point to the ending point (apex) which prob means that diff parts of the cochlea respond best to different sound frequencies

which embryological structures is the brainstem in?

- the diencephalon (sometimes people do not include this b/c they don't say the hypo/thalamus are part of it) - the mesencephalon - the metencephalon (ONLY pons NOT cerebellum) - the myelencephalon (includes midbrain and hindbrain but excludes the cerebellum)

Where is the basal ganglia located?

forebrain, around lateral to the thalamus which is more midline - it looks like an earphone earpiece

Support for trichromatic theory

found in digital color mixing: easy to see in a color mixing tool, she used RGB sliders - so you have red, green and blue and it allows you to adjust the values of each of them to combine them and get diff colors Ex. If you have full red and full green all the way up (no blue) it gives the color yellow

Amygdala Functions (Limbic System)

got its name b/c it looks like an almond - one on each side, curling out into the temporal lobe - FUNCTIONS: plays key roles in threat detection, fear, excitement, and arousal - lots of diff sensory systems send inputs directly to the amygdala, takes in info from enviro, monitoring it and if it detects a threat then it initiates fear responses - key player in emotions AND behavior, response to stress, and response to anxiety (how amgydala balances threat detection)

basal ganglia FUNCTIONS (forebrain/telencephalon)

group of subcortical structures in the forebrain that help to control and filter movement (NOT part of cortex) - target of dopamine releasing cells in substantia nigra - FUNCTIONS: associated with motor control and reward - role in implicit procedural memories which are the skills that you know how to do ex. typing on keyboard without thinking about it/looking which is a motor memory thanking the basal ganlia ex. if you have learned to play an instrument and you can still play the certain notes based on the sequence of motor actions

Case Study: Patient H.M.

had hippocampus removed due to severe epilepsy --> had severe anterograde amnesia and retrograde amnesia for memories shortly before the procedure. Showed that the hippocampus is responsible for the consolidation of STM into LTM notable b/c we learned for the first time that there are diff types of memories and cutting out the hippocampus creates profound amnesia and memory problems. (the book is written by the grandson of the surgeon)

remembering the way to class so it can learn things

hippocampus

What photopigment is found in rods?

rhodopsin - composed of opsin and retinal - sensitive to dim light in the blue to green range of the electromagnetic spectrum (short /medium wavelength)

meaning of hippocampus

seahorse, greek "hippokampos" - this can help us form a new declarative memory and remember some functions of the hippocampus

compare rat vs sheep vs human brains

sheep brains: size of your fist rat brains: size of thumb form the tip to the knuckle - generally the convolutions are a rough indicator how complex a species' behavioral capabilities are. humans have a lot but sheep do too surprisingly! however, the rat's brain does not have many convolutions (pretty smooth)

blind spot

where blood vessels and the optic nerve leaves the retina - there are no photoreceptors which means NO vision WHY isn't there a hole in our vision? - there are a lot of compensatory mechanisms which means your brain is basically filling in the gaps, it assumes that patterns will continue (the eye is constantly moving all the time which changes which part of you visual field corresponds to the blind spot)

neural functions

transduce light into neural signals, then relay and process those signals (how we actually have the environmental signal translated into a neural signal and how it gets pricessed)

optic nerve

transmits impulses from retina to brain

lens

transparent disk that uses accommodation to focus light rays for near or far distances - accomodation: ability to change the shape of the crystalline lens to focus on objects of varying distances (close or far away) - convex shape ( ) is when we are focusing on a near object - concave shape ) ( is when we are focusing on a far object (pulled more)

aqueous humor of anterior chamber

transparent, gelatinous mass that fills space from cornea to pupil

vitreous humor

transparent, gelatinous mass that fills space from pupil to retina

Amygdala case study violent behavior

university of texas shooting in 1960s - Whitman was 25 yrs old when he killed 15 and injured 21, he was killed by a police officer - in his autopsy, they found that he had a brain tumor and his amygdala was particularly impacted - it is possible that his tumor caused him to be violent BUT there are many who do not go on shooting sprees - not a one size fits all system regarding amydala OR violent behavior

inputs of thalamus

using DTI (80 diff cortical sites) they mapped out the connections to the thalamus. there are a LOT, not just input from the sensory cranial nervies but also diff cortical sites which help modulate our sensory attention and ability to perceive sensory info

age related macular degeneration

usually genetic and affects the elderly - someone with this condition shows a dark spot right where they are trying to focus. this dark spot is called a scotoma which impairs ability to read/watch TV. it affects ONLY the central field of vision. - the peripheral vision is largely okay but as you get to the center it gets distorted - the macula contains the fovea which affects the center of our field of vision but the periphery is relatively intact

efferent nerve

ventral motor CNS to body

5 senses myth

we actually have a lot more! - ex like nociception which is the sens of pain or proprioception which is the sense of how our bodies are positioned, etc

what are species that do not have duplex retinas?

rats and owls have almost entirely rods squirrels and lizards have retinas that are almost entirely made out out cones (which is why they are not out at night, no night time vision)

photoreceptors

respond to light - rods and cones

what is one of the most overrepresented areas of the brain

prefrontal cortex

pupil

the black opening inside the iris that allows light to enter the eye

cerebellum functions (hindbrain)

"cerebellum" = tiny brain - contains about half of all the neurons in the entire brain even though it's only 10% of the brain's volume; neurons are densely packed - FUNCTIONS: controls speed, intensity, coordination/balance, direction of complex VOLUNTARY movements, speech - part of brain that gives us our "gracefulness" - connections between speech and balance - you trip and do those flailing motions to avoid falling down, whenever you do those motions to correct yourself that's the cerebellum! it is understanding what you wanted to do and what is actually happening and trying to adjust your motion in the middle so you don't fall down

pons functions (hindbrain)

"pons" = bridge. is the more bulgier part of the brainstem - most of the pons are axon pathways that connect diff parts of the cerebral cortex to the cerebellum - involved in audition (sense of hearing), balance, sleep, excitatory arousal, motion sickness (this is a lot b/c it is a main highway of info travel) - contains synapse points for the vestibular nucleus (8th cranial nerve) for balance - cochlear nucleus is major part of the central auditory pathway (sense of hearing) - contains releasing centers for some neurotransmitters (like mentioned in pharmacology, it is the "hub"). - ex. it contains the Raphe Nuclei that is one of the major releasing areas of serotonin that basically goes throughout the whole brain - ex. Locus coeruleus which is a major releasing area for norepinephrine

Horizontal plane (localization of sounds)

- Allows us to compare the arrival times of sounds at each ear. Since your head is a solid object, the sound will hit one ear faster than the other and is a measurable difference except if it is coming exactly in front of you or completely behind you in the center. Otherwise, there will be one ear that gets the signal first. The ear that gets it first is the source of the sound and so we orient that way to try and identify the source. - binaural neurons in the superior olive. The comparison of arrival times are in the superior olive. It is called binaural b/c it gets input from both ears. - differences in intensities/timing of sound reaching each ear lets us know which way to orient LEFT TO RIGHT PLANE

using left brain more than right brain MYTH

- It is not true, certain sides of the brain are used for specific functions, but there is no evidence of a left or right dominance in inidividuals - so we use both sides equally

Organ of corti

- On the base of the basilar membrane of the cochlea - Composed of hair cells which have connections to spiral ganglion cells and these dendrites bundle together to form the auditory nerve fibers - Transduces movements of cochlear partition. (Transduction occurs in the hair cells which are the organ of corti) Similar to what we have in the retina in that we have the receptor cell where transduction actually happens , some ganglion cells bundled together, and the axons are going to use action potential

Parts of a hypercolumn

- Orientation Column: Responds to lines of any particular angle (but only that same type of single angle) for a single eye, made of Simple Cortical Cells - Ocular Dominance Column: Responds to input from either the left or right eye, but not both. Preferred orientation changes. A little bit bigger - Movement is processed by complex cells - Color/sight is processed by cytochrome oxidase BLOBS (at the top)

The inner ear

- Semicircular canals (part of vestibular system) - cochlea (auditory transduction) which gots its name b/c it resembles a snail shell

Case Study: Phineas Gage

- a foreman working on the railroad in 1848 his iron rod that went right behind his cheek bone, through the back of his eye and out the top of his skull - he suffered a traumatic brain injury when an iron rod was driven through his entire skull, destroying much of his frontal lobe. - Gage's personality was changed dramatically after the accident: BEFORE he was responsible, quite, mild-mannered, had respect AFTER: dies 12 yrs later b/c of epilepsy, but he became impulsive, rude, his vocab was more foul, he lost his job (joined the circus) - one of the first clear demonstrations that brain damage can influence a person's behavior in a systematic way - around the time of stepping away from phrenology and into localization of functions

LGN thing to remember

- at this point, the visual fields are completely contralateral (info from each eye is processed separately) - BUT remember that each eye is contributing to that portion of the visual field Layers 1 and 2: associated with the magnocellular pathway Layers 3-6: associated with the parvocellular pathway (Video 8 3:47)

Trichromatic theory of color vision

- based on the idea that we have 3 cones (photoreceptors) that are sensitive to diff wavelengths (like short, medium, and long) - also called the young-helmholtz theory, they mathematically theorized that in order for this to work you would need about 3 different photoreceptors. They made this theory a really long time before we knew we had cones that are sensitive to 3 diff wavelengths (short=blue, medium=green, long=red) - we see that when blue, red, and green light can be mixed to generate all colors, and combining them all together gives us white light. So varying levels of activity in the 3 diff wavelength sensitivities can allow us to perceive a lot of diff colors (like purple, yellow, etc) - when we graphed the sensitivities of the 3 diff cones, we found that it is a parabola/curve. Since, it is a curve, there are 2 points on the parabola that create equal firing rates which are at very diff colors/wavelengths but if that cone is our only photoreceptor then we can;t tell them apart. Once we incorporate all 3 overlapping curves of the cones, then we can look at the activity in one area. So it is the combination of the small cone, medium cone, and long cone that lets us see the color blue. So even if a cone is not at its peak it is still responding on a diff level at smaller wavelengths. - so we look at the activity in the short sensitive, medium sensitive, and long sensitive. The combination of the 3 levels of activity is what allows us to see the shade of blue (on the shorter wavelength side) - we go to the opposite end, we look at the activity in the long sensitive, and medium sensitive where there is no activation in the short sensitive cones. This combination tells us that this is the color orange (longer wavelength side) - having 3 curves takes away the opportunity to confuse/ambiguate diff levels at the same response that correspond to diff wavelengths (b/c as we said the parabola gives us 2 points that give equal firing rates)

Primary auditory cortex (A1)

- columns respond to single frequencies/are frequency sensitive and is typically arranged from lower frequencies to higher frequencies - columns can respond to input from either one or both ears

forebrain segments

- diencephalon (thalamus, hypothalamus) - telencephalon (subcortical structures, cerebral cortex)

Pitch perception

- due to the combination of frequency, intensity, and context of stimulus - auditory cortex has tonotopic organization, (this is the same thing we have seen in the motor, somatosensory, visual cortex) where it just has an organizational plan. SO pitches are processed near each other in the auditory cortex not necessarily randomly all over the place

Fovea/cortical magnification

- even though the fovea is a really small percentage of our retina, in the primate visual cortex (true for us and other primates) we see that V1 actually expands its representation of the fovea (central vision, color) - retinal vs cortical map: the cortical map really emphasizes the center of the image

Amacrine cells

- form connections between bipolar, ganglion, and other amacrine cells (input: bipolar output: ganglion and some amacrine) - analogous to the horizontal cells (integrate/combine visual messages across the retina) - they may play a significant role in how we process movement in our vision

inputs and outputs of cerebellum

- gets inputs from spinal cord (info of what is HAPPENING, :"oh I just tripped, im falling"): current location of body - gets inputs from cerebral cortex (primary motor cortex) via pons that carry the pathways: this is where we are making the PLAN for any voluntary/intended movements - the cerebellum helps initiate a sort of corrective action to try and avoid falling down; it implements the motor plan and corrects as needed

Complex V1 cortical cells

- have a much larger receptive field - there are no inhibitory regions (gray regions, the "off") - shows preferred stimulus size and orientation (like vertical or horizontal or anything else), but not location within the visual field (as there are no "off" regions) - sensitive to unidirectional movement. So it is still something angled in a particular way, but it is moving in one direction and NOT the opposite. - in the specific example that favored vertical lines, we see that whenever we have the vertical line in the receptive field we have peak action potentials (can be many diff ways to achieve this) - if it is less vertical, then we have less action potentials as it is not the preferred orientation of the cell (the least would be the opposite of the preffered, so it would be horizontal in this case)

blindsight (occipital lobe damage)

- if someone has functioning eyes and most of their visual pathway is intact BUT the damage occurs in occipital lobe then there are some small branches of that visual pathway that sends visual info elsewhere - SO if the damage is due to cortex damage, then you can ask them questions about a visual stimulus and they will have no conscious perception of seeing the image but if you ask questions about it they do better than chance ex. they are in a room and say point to where the circle is and they're like "this is stupid, I can't see anything i am blind" but when they just point it out it ends up being where the circle is. this is because there are other branches in the visual system are getting something even though they have no conscious experience of seeing it

damage to cerebellum

- in some cases we may see movement/balance/coordination problems - in other cases we may see speech problems - may be subtle effects on cognition (type of learning called eyeblink conditioning) so forming the association between certain types of stimuli ias associated with cerebellum - Autism spectrum disorder? (may be some altered patterns of connections in cerebellum in individuals with Autism which could explain some of their movement/cognition/social issues

Secondary auditory cortex

- just like in vision, we think we see separate pathways coming from the primary auditory cortex that process the quality of a sound (ventral = "what") and its location (dorsal = "where") - these secondary cortices are activated by more complex stimuli (like voices or rhythm associated with music

Magnocellular (LGN layers)

- large cells. Layers 1 and 2 - receive input from M ganglion cells - respond best to large, fast moving objects (objects in motion) - they have large receptive fields which lets them perceive the motion

where does light come from

- light comes from electromagnetic radiation which is abundant in our universe - it has advantages: travels very quickly (speed of light), travels in fairly straight lines - light is both a wave and a particle

Thalamus functions

- receives sensory info and regulatory info - gateway to the cortex or sensory switchboard (except smell) - participstes in states of consciousness (especially early stages of sleep), learning and memory - it can filter how much info gets delivered to the cortex depending on the state of arousal which is important for determining what wakes you up when you first start to fall asleep (does not "change" the info though)

hypothalamus FUNCTIONS

- main regulatory center: works llike a thermostate; is responsible for maintaing a constant internal state (homeostasis) - regulates eating (hunger), drinking (thirst), sex, biorhythms (regulating amount of light/how it can influence circadian rhythms), temperature control - is like a thermostat in that it has a set value for a biological category and has a little range of deviation outside of that but if you go too far it initiates mechanisms that help us get back to balance/homeostasis - collection of specialized nuclei (there are subdivisions) - hypothalamus controls the pituitary gland (hormones) - directs the autonomic nervous system in regulating if the sympathetic or the parasympathetic should be more active or less active which comes in to play when we talk about stress response and our emotional connections so it adjusts the diff hormones in pituitary gland to regulate sooo many diff functions like love, hunger, thirst, fatigue, temp, etc

Frontal lobe structures

- most rostral/anterior part of the cerebral cortex - contains primary motor cortex, prefrontal cortex (PFC), dorsolateral PFC, orbitofrontal, and Broca's area (language: actual generation of speech), language processing - roles in motor function, language, memory, many "executive" functions executive = think about how a CEO spends their day. lots of meetings (communication). a strategic 5/10 year plan (identifying goals and working towards them) - it also inhibits impulses

hindbrain segments

- myelencephalon (medulla) - metencephalon (pons, cerebellum)

reticular formation ("reticular activating system") (hindbrain)

- netlike mixture of neurons and nerve fibers throughout medulla and pons. NOT a discrete structure like other parts of brain. - reticular = netlike. it is a connection of neuron/axon fibers that form this net structure - has a stimulatory role, increases the excitability of the forebrain as well as others - FUNCTIONS: associated with states consciousness/sleep stages, excitatory arousal (not sexual), attention, movement, pain - we focus on the sleep stages/consciousness the most

Hippocampus FUNCTIONS (limbic system)

- new declarative MEMORY formation: the facts and info that you're learning (even in this class) (will later involve other brain regions but it starts in the hippocampus) - spatial infomation processing. when talking about single and multi unit recordings we talked about the place cell that fires activity in a certain place in space so hippocampus is useful for things like remembering where you parked your car and how to find it - stress feedback: one of the areas that is hit hardest by a prolonged stress response (the longer you are stressed the harder it gets to actually learn/remember info)

subregions of basal ganglia

- nucleus accumbens - CAUDATE NUCLEUS - PUTAMEN - GLOBUS POLLIDUS - subthalamic nucleus - substantia nigra (part of midbrain but since it is such a functional circuit some include it in the basal ganglia umbrella) NOT tested on all but there is a lot of overlap and confusion with what is actually part of the basal ganglia - the basal ganglia is able to help influence excitation/inhibition through the thalamus

Loudness perception

- primarily depends on the decibel level which describes the physical qualities of the sound stimulus - larger amplitue of a sound = the more vibration and the more shearing force of the tectorial membrane of the hair cells. - we perceive the amplitude through loudness (how loud it is) - equal loudness contour

temporal lobe structures

- primary auditory cortex (hearing) - lots of visual and auditory association areas which both have a ventral pathway for processing info and many of those areas go through the temporal lobe - Wernicke's area which is important for understanding language/having right meaning - contains most of the limbic system, (lots of the structures "curl" out through the medial temporal lobe)

parietal lobe structures

- primary somatosensory cortex (area most important for responding to touch) - wholllleeee lot of association cortex here that is important for auditory/visual/touch ots of diff sensory processing - specialized for skin senses and senses that inform us about BODY POSITION and movement, spatial perception - "personal space in relationship to other things"

occipital lobe functions

- primary visual cortex - "blindsight" if damaged - the origin of photosensitive epilepsy occurs here (where the specific frequency of light flashing can cause an epileptic event)

Pure tones vs Complex tones

- pure tones feature a single frequency and have a pure sinusoidal wave. Pure tones are those that are usually annoying sounds like alarms or beeps - complex tones: produce timbre (multiple frequencies nested in). There are most of the sounds that we listen to. Timbre is the property that allows us to play a musical note that is the frequency on different instruments but has a different quality to the sound (due to the timbre which is the different other frequencies)

The optic nerve (cranial nerve 2)

- purely sensory function - made from the ganglion cell axons that bundle together. They then exit each eye through the optic disk which is where the blindspot is, it then forms the optic nerve (CN II) leaving each eye - about 50% of fibers cross to opposite hemisphere at optic chiasm, really does look like an X at the bottom of the brain

Veritcal plane (localization of sounds)

- really important for the shape of the pinna which is designed to focus the sound into our auditory canal so it can be perceived UP AND DOWN PLANE

Bipolar cells

- receive input from photoreceptors OR from the horizontal cells - provide output to amacrine cells and ganglion cells - these communicate through graded potentials - 2 categories: diffuse: very big, more common in the periphery of retina meaning it is from RODS, we see a lot of rods (50) converging onto one diffuse bipolar cell midget: smaller, from photoreceptors in the fovea (meaning they get their information from CONES and are associated with color), we see one cone will go onto one midget bipolar cell - this is a reason why our most detailed vision comes from our cones: b/c of the idea of keeping it small (one cone to one midget bipolar cell) - Bipolar cells respond to light that fall in receptive fields - bipolar cells have an antagonistic center surround receptive field/organization: think an image of a donut - gives rise to features of vision called lateral inhibition

Horizontal cells

- receive input from the photoreceptors and provide output to bipolar cells - major task of these cells is to integrate info from the photoreceptors that are close to one another - the spreading structure of the horizontal cells is well suited to the task - like the photoreceptors, the horizontal cells communicate through formation of graded potentals

cerebellum case study of 24 yr old Chinese woman

- the entire cerebellum was missing - she went to the hospital b/c she was feeling extremely dizzy and nauseous - they scanned her brain and it was gone this is called "total cerebellar agenesis" where basically the cerebellum did not grow at all! - This woman had developmental difficulties - she did not speak until age 6 (atypical is 1 or 2) she did not learn to walk until 7 and even as an adult she could not walk steadily w/o support so speech and motor/coordination problems like you would expect - the cerebral spinal fluid (CSF) actually filled the gap and created a buildup of pressure of her CSF so she had an increased cranial pressure. they treated her w/ a specific type of dehydration therapy to reduce the pressure buildup which treated her dizziness/nausea - she now is fine, is married, and has a daughter who is completely neurotypical

how do we protect our eyes

- the eyes are located in a "bony orbit" of the skull, so almost all angles of the eye is protected by bone except for the front where we need to see - it is cushioned by fat so it is held in place - the purpose of eyelids/eyelashes/blinking is to help prevent dirt/debris from gettiing inside our eyes (it is painful when dirt gets in b/c it can damage the eyes very quickly) - tears which are produced from the lacrimal gland protects our eyes by constantly cleaning it by washing out the dirt (if we encounter an eye irritant we might tear up/watery eyes)

Visual processing areas of thalamus

- the optic tract comes in and is one of the main sources of input to the lateral geniculate nucleus (LGN) which is like a sensory relay station - one of the main sources of output is the primary visual cortex (in occipital)

BRAIN initiative

- their goal is the Human Connectome Project. and has become a funding priority in the US and research institutions - the brain now: we focus on important regions and their key functions associated with it and what happens when it is damaged brain in future: the important circuit for a specific behavior we may see a change from the regional approach to the important circuits. this can allow us to tap in to new/unimaginable levels of understanding brain anatomy and brain function

Visual analysis beyond V1

- there are at least a dozen other cortical areas that participate in visual processing other than V1 PATHWAYS: - the dorsal stream, the ventral stream

what to keep in mind going forward regarding brain structures

- there are roles that the brain structures are most known for but any behavior of interest is going to involve a lot of brain working together in communicaton - an area is actually defined by its inputs and its outputs so that integrated communication view should be kept in mind as we think about what the structures are most well known for

Organizational principles of V1 (primary visual cortex)

- topographical mapping: remember when we talked about sensory/motor cortices we said there is a body plan that mirrors the brain organization, we see the same thing in vision. It isn't just visual field parts all randomly next to each other, but if it is near each other in the visual field, it is going to be processed near each other in the brain - locations on the retina and LGN correspond to locations in V1: ex. when we see how the right visual field of 5-9 was processed, it shows that the image that corresponded to 5 was near 6 so it is near each other in V1 - fovea magnification: fovea is where we get the most detailed vision and color image and each cone goes to one of the diffuse bipolar cells. So with fovea magnification we see that central vision (5-7) has a lot more representation than the peripheral vision (7-9). Showing shrinking proportion of V1 being represented

The ventral stream ("what")

- towards the bottom of the brain, goes down into the temporal lobe - OBJECT RECOGNITION: "what" stream, down in the temporal lobe is where we have a lot of language/memory areas which is important for looking at an object and knowing exactly what it is - areas V4, IT, and the fusiform face area (FFA) which are in the inferior temporal lobe. The FFA responds more to faces than any other stimulus. If someone has damage here: prosopagnoisa. - Prosopagnosi: This means face blindness due to damage in the FFA: ("the man who mistook his wife for a house") a man could recognize his wife by sound and other cues but could not look at his wife's face and know who it was. He had No visual recognition of any faces.

Processing Color Vision: theories

- trichromatic theory - opponent process theory

effects of below the injury of the spinal cord

- typically loss of sensation from the skin and internal organs - loss of voluntary movement - loss of voluntary control of bladder and bowel (the sacral region)

Bionic treatments to help with sensory impairments

- uses a video camera to bypass the eye (goes around it) and uses a retinal implant to trigger the optic nerve and send it along the typical brain pathway that we have learned so far - not perfect but signs for bettering improvements ahead

unilateral neglect (parietal lobe damage)

- usually occurs when the right parietal lobe becomes damaged. - remember contralateral processing so that right damage means that there is no left in a person's world. is pretty profound ex. so if someone has this condition they may dress just the right side of their body ex. if they have a plate of food, they may eat everything on one side and think they're done but if someone rotates the plate they think "oh hey more food!" and they'll happily eat it

Similarities between vision and hearing pathways

- we had vision going to the superior colliculus whereas hearing goes to the inferior colliculus - we had vision going to the LGN whereas hearing goes to the MGN in the thalamus - we had orientation columns in the visual cortex whereas we see columns in hearing pathway respond to single frequencies - we have primary/secondary cortexes in both vision and hearing

Resting potential of hair cells? What occurs at a moderate action potential hair cell

-70 mV - normal what we expect it to be - the hair cell is in a vertical position and it is all about the tension on the tip links. The tip link is going to pull open the channelson the tallest cilia and allow ions to flow in creating depolarization and some glutamate release. - then the spiral ganglian neuron (analogous to the ganglion cell in the retina) is going to fire some action potentials. - this is the baseline rate of firing

How many ganglion cells do we have

1 million - this means we are converging on a lot of information - each ganglion cell is going to represent a much greater proportion of the visual field than the bipolar cells or the photoreceptors that were the first start of the signal

On center bipolar cell

1. Baseline condition resting potential -70 mV 2. Light in just the center, we see a high spike in activity, this is the preferred stimulus (on center). Hyperpolarizes the photoreceptor and depolarizes the bipolar cell 3. Light in just the surround, we see low spike activity. Depolarizes the photoreceptor and hyperpolarizes the bipolar cell 4. Diffuse light (light in both the surround and center). Not much of a differences. Just slight depolarization of the bipolar cell.

Central auditory pathway

1. Bipolar spiral ganglion neurons connect the cochlear hair cells and the dorsal/ventral cochlear nuclei of the medulla to the auditory nerve (CN 8) 2. Those Cochlear nuclei synapse with the inferior colliculus in the midbrain (the inferior colliculus is important for auditory orienting reflexes: someone yelling your name and you do the spin move to find out who it is) - direct connection from the dorsal cochlear nucleus to the inferior colliculus - indirect connection from the ventral cochlear nucleus via the superior olive (which is important for localizing where the sound actually comes from 3. The inferior colliculus projects to the medial geniculate nucleus (MGN) of the thalamus 4. The MGN then prjects to the primary auditory cortex (A1) which is located in the temporal lobe. Heschl's gyrus

what is the most fav lobe

1. FRONTAL 2. distant is occipital 3. hardly any for temporal 4. barely anyone says parietal why? many like the higher order behaviors that are associated with the frontal lobe

On center ganglion cell

1. Firing at a baseline regular amount (moderate action potentials) which allows us to increase/decrvease the rate of firing (the only thing you can change about an action potential is how often they occur). It is also dark. 2. Light is on in just the center, a big spike in the number of action potentials while the light is on 3. Light in just the surround, we see low spike in activity. A reduction in the amount of action potentials 4. Diffuse light (in both the surround and the center). Most similar to the total darkness condition (1). B/c it cares about contrast. When we have that difference between the center and surround we have the contrast, but here we don't.

Off center bipolar/ganglion cell

1. Light in just the center, we see inhibitory/hyperpolarization of bipolar cell which results in few action potentials in the ganglion cell 2. Light in just the surrounding , we see excitatory/depolarization of bipolar cell which results in the most action potentials in the ganglion cell (preferred stimulus)

Cross section of the retina

1. Light passes through 2. Processed by the photoreceptors 3. Had one step of the pathway in the bipolar cells 4. Ganglion cells

TYING IT ALLLL TOGETHER: LIGHT ROD TRANSDUCTION

1. Light travels through all of the cells until it gets to the photoreceptor 2. In the presence of light, the photoreceptor (rod) is going to hyperpolarize 3. This is then interpreted by the bipolar cell to know that light is present 4. When light is just in the center of the receptive field, the bipolar cell is going to depolarize 5. The bipolar cell is going to communicate with ganglion cell which interpret the presence of light in the receptive field 6. If the light is right in the preferred area, the ganglion cell going to increase the amount of action potentials 7. The axons of the ganglion cells are going to bundle together and form the optic nerve and head towards the brain * this highlights which cells use graded potentials (photoreceptors/bipolar cell) and which use action potentials (ganglion cells)

steps in the visual pathway in human vision (full functional circuit)

1. Right and left visual field to retina (transduces signal to neural signal) 2. Optic Nerve (II) to Optic Chiasm (crossing over) to the Optic Tracts 3. (90%) Lateral geniculate nucleus (LGN) of thalamus 4. Branches off into Optic radiations to Primary Visual Cortex (V1) in Occipital Lobe 5. Processing splits onto a dorsal and ventral pathway (?) of Secondary Visual Cortices (2)

Tracking of light thru the eye

1. We have the optic nerve which is a combo of both left and right visual field 2. Then, we have the optic chiasm which is where they crossover 3. After, they become completely contralateral and they are called the optic tracts 4. Goes to the lateral geniculate nucleus target in the thalamus which has totally separate visual fields (contralateral) 5. We then make it back to the occipital lobe and we still have these separate visual fields

Threshold

A sound that is perceived more than 50 percent of the time (0 dB). 0 decibels is like hearing the wings of a fly flapping near your face

sound transduction

1. We have vibration 2. Causes the tympanic membrane to vibrate 3. That vibration is amplified by the ossicles 4. Vibration is transferred to the oval window 5. The oval window causes the fluid inside the cochlea to start vibrating 6. Waves travel backwards along the tympanic canal from the apex to the round window (another membrane) that bulges out so we can release the pressure of the vibrations

Overview of steps in phototransduction of the rod

1. With light we close the channels to the outer segment 2. This causes HYPERPOLARIZATION in the cell body 3. Reduction of neurotransmitter (GLUTAMATE) at the synaptic level that would go to other neurons 4. Bipolar cell knows that the hyperpolarization means that there is light present/photons **GRADED POTENTIALS: this hyperpolarization means that the more photons, the less neurotransmitter - because it is graded potential we have the opportunity to modulate the size of the signal which is something we do not have with action potentials

what are the 3 things that can happen to light

1. reflected: like a mirror where light hits it and part of the wavelength will bounce off 2. absorbed: taken into part of the object 3. refracted: like bent air and water can change the way the traveling waves of light move (important for how we process vision)

what are the two main categories of the midbrain

1. tectum ("roof"); more dorsal portion 2. tegmentum; more ventral portion

case study: Devin Wright

14 yr old British teenage who went on a family vacation to Italy - he shot himself in the gun with a spear gun. very dramatic trajectory - he is expected to make a complete recovery after shooting himself through the eyes and brain

timeline for evolution of the brain

18 hours ago: first single cell organism 3.75 hours ago: first nervous system (jellyfish) 2.70 hours ago: first brain (lamprey) 2.5 minutes ago: first hominins 3 seconds ago: homosapiens - the brain is really new on the scene in the big picture perspective

how do we connect the hemispheres of the brain

2 main fiber bundles: Corpus Callosum and Anterior Commisure - remember that many things are processed contralaterally, or on the opposite side, which means we have to have pathways to cross over MAIN HIGHWAY: Corpus Callosum this is not the only way that info can cross, there are other "backroads" like the Anterior Commisure, pathways in thalamus/hippocampus, etc

cerebral cortex

= "bark" - the outermost portion of forebrain - some areas are dedicated to specific senory processing of one type of sensory modality, froming/organizing motor plans, areas called "association cortex" where they aren't purely sen/moto but have. - many diff functions, and higher brain functions and complex thinking that are more advanced - divided into 2 hemispheres (right and left) the left/right brain personality is mostly false but there are some functions that are more localized in one hemisphere - grey matter is superficial (on the outermost portions is where the highest concen of cell bodies is) , white matter is deep (more internal, pathways of fiber connections)

Orientation columns (organization)

A column in the visual cortex that contains neurons with the same orientation preference (responds to lines of a single angle) - the funky image is misleading as it has been color coded to represent the angle of lines so we are looking at where the receptive fields for specific angles are (NOT looking at color vision). - every angle is represented in a nice pinwheel fashion in each column. This means that if you are recording from one site and you go all the way down vertically then you are going to be recording from cells that have the same orientation - we talked about how the cortex has 6 layers, but the cortex also has a vertical organization plan called columns

Auditory Canal (Ear Canal)

A hollow tube shaped opening which flows the sound from the outer to middle ear - the length and shape enhances certain sound/resonant frequencies (just like in instruments) - our ear canal is best tuned to process the cry of a baby, It causes the perfect resonant vibration in our auditory canal

Sensory adaptation

Activation is greatest when we first detect a stimulus - this is because your nervous system is very biased towards change/novelty. As the stimulus remains constant, we notice it less and less Ex. You live in an area that has a lot of construction noise. The first couple of days you hear the noise it really bothers you. But after a week or two and the noise is continuing, you notice it a lot less than you did before. The noise is the same but you are changing how much you care about it and how much you notice it. Ex. When you stick your toes into a pool and it feels soooo cold. But after a little time, you no longer notice how cold it is. The temperature has not changed, but your perception of it has - appleis to all senses

Hearing issues/conditions

Age related hearing losee: Most common, likely to affect the higher frequencies in our hearing range - due to poor circulation over time, general life experience of exposure to loud noise, worsens over time Damage to outer or middle ear - conduction loss due to wax build up, ear infection, or otosclerosis (hardening of bones/muscles in there) - commonly treated with hearing aids to amplify sounds even further. However, aids amplify ALL sounds, including distracting background noises. Damage to inner ear, auditory pathways, or auditory cortex - damage to the cochlea in the inner ear may be treated with a cochlear prosthetic

Lateral inhibition of oncenter ganglion cells

All of these receptive fields are located near each other and gives us the ability to understand contrast and where borders/boundaries actually are diff receptive fields in the light, as well as the transition points between dark and light and we are looking at the #of action potentials in the on center ganglion cell On center Ganglion cell A: when the cell is in complete darkness, the activity/response is at baseline On center ganglion cell B: a litter bit of light in the surround only, this reduces the amount of action potentials On center ganglion cell C: half light in center half light in surround, so we see some excitation and some inhibition which cancel each other out giving us baseline On center ganglion cell D: center is fully in the light while only a portion of the surround is, this gives us the MOST firing b/c the center is fully illuminated and we do not have all of the surround On center ganglion cell E: both center and surround are fully illuminated, having more of the surround illuminated reducesthat firing away and gets it more to baseline

April 2019

Article noting the first ever middle ear transplant using a 3D printer to make the ossicles out of titanium. They then surgically implanted them and they worked! - the patient had their ear damaged in a car accident, so all the other structures were in tact.

Presbyopia

Associated with old age - the crystalline lens hardens (it is fairly elastic/stretchy when young), the lens becomes sclerotic (harder) and the capsule that encircles the lens which enables it to change shape, loses its elasticity - cannot focus on things as closely (like hyperpopia) - the reduced rate/extent of accommodation by the lens as a result of age - they may spend time trying to find the magic perfect distance to read the newspaper. They are adjusting behaviorally since they can not move their lens

The McGurk effect

Auditory illusion that occurs when we combine vision and hearing. It is what happens when those signals are mismatched/not in agreement. You hear someone repeating on syllable (ex. Ba Ba). Then you watch the video and the lips are making a diff movement (ex. Ga Ga). So you hear Ba Ba but you are seenig Ga Ga and your auditory perception combines the two so that you hear Da Da. - Meaning their are lots of cues that guide our perception beyond the stimulus itself and how our senses combine to enrich and confuse our interpretation of world Entire logic of ventriloquism is b/c we are looking for a visual cue to know where the sound is coming from. Where we interpret it as the sound coming from the doll even though we know it is coming from the human.

Which color process is right

BOTH - we have the trichromatic theory which allows us to perceive the world according to actiuvity in the relative levels of the short, medium, and long wavelength sensitive cones - we also have the opponent process that allows us to differentiate red/green, and blue/yellow. Our rods come into play which allows us to differentiate between black/white and shades of gray

Why do we get annoyed when someone near us is crunching on some food?

Because we do not have our tempor tympani/strapedius muscles tensed when other people are eating. - usually, the sounds we find most annoying is due to the fact that normally those muscles would be tensed to mute those sounds. But they aren't during other circumstances

Generally what is the order of cones and rods in the wavelength spectrum

Blue short cones Long rods Green middle cones Red long cones

Led Zepplin, "Stairway to Heaven"

Bottum up: no expectations. Just listening to the song's lyrics backwards. It sounds muffled, no particular words jump out Top down: influence when moms started to listen to it backwards they believed they heard a satanic message and the expectation of what to look for spread. You can totally hear the words once she tells us what to look for. Great example of how we can use either the top down or bottum up processes to guide our experiences

The middle ear

Boundaries of the middle ear are formed by two membranes (the area between two separate membranes or flexible tissues): Tympanic membrane and the oval window Ossicles, Tympanic membrane, The oval window

Cones (photoreceptors)

CONES: used for photopic vision (bright light, walking in the sunlight, floursecent bulbs) - responsible for all the color we see and high acuity (detailed vision) - high density in the fovea (pretty much only found in the fovea) - 6 million photoreceptor cones in humans STRUCTURE: cones are like cones (triangle) AND SHORT

why has the brain developed so quickly?

COOKING (dr susana on TEDtalk) - once we developed the ability to cook our food we were able to consume a lot more calories a lot more quickly which allowed for the growth to expand - whereas other similar nonhuman primates (like chimpanzees/gorillas), they spend almost their entire day eating to try and get the amount of calories they need

Basal ganglia: subregions you should know

Caudate Nucleus: the curly portion highlighted in white Putamen: the bulk of the central egg shaped portion Globus Pallidus: a more internal subregion collectively forming the basal ganglia

Where are the hair cells in the cochlea?

In the basilar membrane - also contains the inner hair cells (organ of corti) that are important for auditory processing of sound

Color blindness vs color anomalous

Color anomalous is a better term because color blindness implies that you can't see something. Color anomalous: a term for what is usually called color blindness. Most color blind individuals can still make discriminations based on wavelength and see colors. Those discriminations are just different from the norm (and might not be able to differentiate some colors)

unilateral neglect drawings

Copying a drawing: they can perceive it and draw a clock, they know it is a circle but they miss the left side of the house, clock, flower Spontaneous drawing: from memory: it misses details on the left side of the man's face - the clock! they comprehend that a clock is round and has 12 numbers BUT filled them in exclusively on the right side of the clock these patients seem to have left but they just can't acknowledge it, it is a disorder of attention! Memory study: ex. a patient in Italy listed all the buildings on the right side of stree "image your on the other stide of the town and you're standover here" and then he listed all the buildings on the other side of the street so somewhere he had that entire representation but couldn't acknowledge anything on the left when in that PERSPECTIVE

Visual fields

Correspond to what is happening out in the world, your vision. Part of the environment registered on the retina - shorthand divide this into the left visual filed and the right visual field. Remember the contralateral processing so the right visual field is processed in the left hemisphere of brain (that does not mean right eye) - it does not mean right eye because we have a lot of overlap where each eye is processing some aspects of the visual fields. For example, the left eye processes 1-8, everything but the most extreme portion of the other visual field The right eye processes 2-9, everything but the most extreme portion of the other visual field - so we do NOT want to think of it in terms of the eye being contralateral, we want to think of it in terms of the visual field being contralateral to brain processing: the left hemisphere processes the entire right visual field (not just the right eye), the right hemisphere processes the left visual field (not just the left eye) - since the eye receives info from aspects of both visual fields, they converge and form the optic nerve, the optic chiasm is the crossover between the optic nerves (half of the fibers then cross over) - so the nasal view of each eye goes contralateral, and the temporal view of each eye stays ipsilateral which results in a full visual field contralateral processing - SO before the optic chiasm the visual fields are mixed, after the optic chiasm the visual field is entirely contralateralq

Regarding rods/cones, what does light do? Advantages?

Dark depolarizes (photoreceptors are depolarized) Light hyperpolarizes (photoreceptors are hyperpolarized) This allows us to have more control over coding for the intensity of the light we experience (as a way of howmuch hyperpolarization has happened) - bright light leads to greater hyperpolarization - dim light leads to less hyperpolarization DISCLAIMER: photoreceptors do not produce action potentials, there are several cells in a pathway before we get to AP. Photoreceptors produce graded potentials

What is the result of rods' response in darkness? In brightness?

Dark: the photoreceptor cell (rhodopsin) is depolarized and results in increased amount of glutamate neurotransmitter Light: the photoreceptor cell (rhodopsin) becomes hyperpolarized and the more light that is absorbed, the greater the hyperpolarization. This results in a decreased release of glutamate neurotransmitter **the glutamate is a major excitatory neurotransmitter

Hearing loss over lifespan

Decibels (hearing level, y axis) vs frequency (hertz, x) - natural consequence of aging, especialy in those over 65 years old whom start to lose frequencies even at 8,000 Hertz - happens to most individualsat varying times/degrees - young people: range of 20-20,000 Hz (high estimate) - by college age: 20-15,000 Hz Treatment: hearing aids. Earliest devices were horns which beethoven actually used. Today we have electronic options

Semicircular canals

Definitely part of the inner ear but they are associated with the vestibular system and our head position. Not necessarily hearing - they do join the ouput from the cochlea and create the vestibulocochlear or the auditory cranial nerve (CN 8) which is going to be part of our path to the brain.

Open K+ channels lead to what

Depolarization and glutamate release

spinal cord case study: derek

Derek was stabbed in the spinal cord with a knife ("clean" injury) - was a case study where they looked at the olfactory epithelial cells which are able to regenerate and then they put some nanotube scaffoldings in there to try to get these nerves to grow and from new connections - he was able to regain some very minimal sensory and motor functions olfactory epithelial cells were taken from nasal cavity (nose) which are self renewing cells, they were then injected into the injury site of the spinal cord, they also took nerves from the ankle and grafted it to the spinal cord injury: the nerve and epithelial cells acted as a scaffold allowing nerve cells to regrow across the gap)

Bottom up processing

Details of perceptual experience influence our expectations Like a detective. Where there are no expectations or other ideas, you are just taking the details as given and trying to interpret them Ex. Looking at an unknown image for the first time. You are using details of the image and looking its colors etc to try to extract meaning from it

Pinnas in the wild

Different species have different pinnas based on their hearing needs. - Elephants have one of the biggest pinnas of all the wild (they use really low frequency sounds).

Astigmatism

Distortion of vision caused by the shape of the cornea, unnevenness in the shape of the cornea - it should be perfectly round, like a basketball. But sometimes it becomes unequally curves like a football

How do dogs perceive the world

Dogs have 2 types of color receptive cones: the green/middle and the blue/short cones. So they can see green, blue, and a little bit of yellow Humans have 3 (blue/short, green/middle, and red/long) Butterflies have 5 types of color receptive cones: they have all the cones humans have, as well as 2 additional cones we don't have a name for. They can see a massive spectrum of color our brains aren't capable of processing. (Pollinators can see UV light) Mantis shrimp: has between 12-16 color receptive cones. The human rainbow stems from just 3 colors, so imagine a mantis' rainbow created from 16 colors - it turns out that it is not better at discriminating the colors we can see, it has actually evolved an entirely diff color vision mechanism that helps them see things faster

Who can hear at larger frequencies: dogs or humans?

Dogs. They can hear at about 24,000 Hz. This is the whole point of a dog whistle, so they can hear it and we can't.

Where do we see the most depolarization in an on center bipolar cell

In the center - this means that the least depolarization is in the surround (inhibitory, off surround)

Where does transduction occur for hearing

In the hair cells, otherwise known as organ of corti.

carrots improve your eyesight: myth of fact?

FALSE the British Royal Airforce managed to gun down German aircrafts even at night and in order to explain how this worked they fabricated a story about how they had a skilled fighter pilot named John catsized cunningham who attribiuted his excellent vision to his carrot enriched diet - started as a total myth but carrots contain a whole lot of vitam a, beta carotene and lutein which are important for maintaining eye health (and general health) BUTTT we can say that eating carrots does not measurably improve your vision it just keeps the eye healthy

Anterior Cingulate Cortex (ACC)

FUNCTION: decision making, error detection how we process/display emotion, anticipation of reward, pain autonomic control - so many functions ex. knowing when we have made a mistake, taking an exam and saying yup i know that was wrong (error detection)

Posterior Cingulate Cortex (PCC)

FUNCTION: eye movements, spatial orientation, memory, consciousness - one of the areas that is hit earlier in the progression of Alzheimer's disease ex. someone who gets lost easily, hard time finding their way might be due to damage hitting the PCC

Human Connectome Project

GOAL: to map all of the connections in a human brain at many different scales - there are more than 86 billion neurons, and how they are connected to each other (LOTS of data) - we want to do this because we know that neurons and brain regions do NOT function by themselves/in isolation; they are part of circuits that influence behaviors - we know these circuits can change through plasticity as a result of experience/learning/new environments - can we create a working model of someones brain and see the difference between people's brains. - microscale: connections of individual neurons mesoscale: projection of a set of neurons (how neurons are forming diff connections) macroscale: traces of many neuron sets (how the entire wiring diagram is set up) - one of the most ambitious scientific undertakings ever.

What are other sources of infrasound?

Geological events Ex. Animals seem to act different right before an earthquake or any hint of seismic activity. The current hypothesis is that the tectonic plate movement is creating some sort of infrasound rumble that they can hear, and we can't.

Lumbar

Gets sensory info and send motor outputs down to our legs which is why we see the horns being some of the largest in the lumbar enlargement We see it declines in the sacral region(Cervical and lumbar enlargements)

Why is color vision important

Historically, females have taken on the role of the gatherer and males have taken on the role of the hunterer. - differentiating between the colors, ex, red and green is a way to know if the food is ripe and safe for consumption

ways to localize sound

Horizontal plane (left - right) Vertical plane (up - down) Vision/Visual cuescan also influience it

Hypercolumns

Hubel and Wiesel proposed that the visual cortex is organzied by ways of hypercolumn - a hypercolumn is basically a millimeter cube of brain that they said would contain all of the machinery necessary to look after everything the visual cortex is responsible for in a small portion of the visual world - so one hypercolumn would correspond to one tiny chunk of the visual field, each hypercolumn would contain cells responding to every possible orientation (from 0-180 degrees). One set preferring input from the left eye and the other set preferring input from the right eye. This is called a ocular dominance column - so each ocular dominance column gets its info from one visual field, but remember that each eye has some components of the entire visual field. Having that overlap in slightly different perspective is another one of those ways we can compensate for things like the blindpsot

Flexor withdrawal reflex

If you have sensory pain that is causing damage (like touching a hot stove) coming in that sensory pathway dorsal afferent then synapsing in the dorsal horn Then the interneuron where you excite the withdrawal muscle and which is going to pull it back (muscle contracts) b/c if we take our time and think about it we are causing more tissue damage (we don't want to do that) SO instead the spinal cord basically controls the whole circuit and then the pain will follow some of those ascending paths in the white matter and goes to the areas of the brain responsible for pain which is why there are a couple of seconds of delay - you do before you know, the spinal cord works fast to contract the muscle and stimulate the withdrawl part to make sure you move your hand as fast as possible away from fire and THEN tells the brain just to let it know - mediated completely in the spinal cord and it's involuntary b/c we don't have conscious control over this process - touching a stove when it was hot and you pull hand away very quickly and it seems like there is a couple of seconds of delay before you register the fact that you have pain

Why is it inaccurate to call the short, medium, and long cones as (respectively) blue, green, and red?

If you look at the wavelength versus activity of the 3 cones you see that the long sensitive cone that is usually called the "red" cone has its peak activity closer to the yellow wavelength NOT the red - and when you have the peak activation of both the medium and long cone (green/red "cones") you actually get the color yellow

Koniocellular (LGN)

In between the magnocellular and parvocellular layers - receives input from K ganglion cells of retina

MICROGRAph FINdingS

In the micrograph, we see the cilia on the hair cells.. - these cells are connected by a filament that is called a tip link. Picture a spring that connects the hair cells together - when we have a vibration that is induced by sound, the fluid is moving (like a wave in the ocean). This fluid displaces the membranes (tectorial/basilar) so we have this vibration/alternation between going upward and pulling on the hair cells and then going the other direction and not pulling on the hair cells (open closed open closed)

Where do we see the most depolarization in an off center bipolar cell

In the outside - this means that the least depolarization is in the center (inhibitory, off center)

Hair cells

Inner hair cells: - these are the ones that convey almost all the info about sound waves to the brain. 3,500 total hair cells (compare with 126 million photoreceptors) - these are used for sensory info about sound (very few of them) 3 rows of outer hair cells: - do not necessarily have a role in the auditory processsing of sound - they convey info from the brain (using efferent fibers) meaning they can use motor output. They can be relaxed or stiffen. If they stiffen, this reduces the amount of vibration of the fluid that can be picked up by the inner hair cells (decreasing action potential). Involved in an elaborate feedback system. - these cells can create those autoacoustic sounds we talked about earlier. Stiffen = suppress noise. Less stiff = tune to specific frequency - they can amplify sound - 10,500 total

tapetum lucidum

Iridescent layer found in nocturnal animals for maximizing vision under low intensity light - the very colorful part behind retina in other animals "laser eyes: flashing back at you, the blue green color is the key that it is reflective - the red eye we see in human pictures is the light going through and illuminating the retina, and since the retina gets lots of blood supply it is going to look red, this is more likely to happen when you have a light iris (blue pigmented irises are more likely to show this in photos)

Where in the thalamus does visual information go?

Lateral geniculate nucleus (LGN)

What happens when you have light shining on both center and surround

Light falling on the center and on the surround of a receptive field does not change the cell's activity. On center and on surround cancel each other out - this creates an excitatory ("on") response in the center and an inhibitory ("off") response in the surround which cancel each other out and the cell remains neutral

On center bipolar

Light hits in the photoreceptive field CENTER. This hyperpolarizes the photoreceptor (rods), releasing less glutamate. This depolarizes the bipolar cell (outside). This works in an opposite manner Getting the opposite effect in the surround involves complex feedback loops. These loops ends up by having more glutamate released and hyperpolarizing the bipolar cells (dark present) SO Light restricted to the center depolarizes the bipolar cell and hyperpolarizes the photoreceptor (rod) Light restricted to the surround hyperpolarizes the bipolar cell and depolarizes the photoreceptor (rod)

equal loudness contour

Looking at sound intensity using decibel scale (log view: very small and very small changes) - we have the auditory threshold (ability to detect stimulus at least 50% of time reliably) - it is NOT a flat line, as there is a diff interaction between frequency and intensity - 80-10,000 hertz is range of human speech (talking). Our threshold at these frequencies is much lower in intensity than it is for frequencies outside of talking. We can hear lower frequencies, if they have a much higher intensity. We can hear higher frequencies, if they have an even higher intensity. - so we see that our ability to perceive a sound as intense corresponds with the dip of the range/"sweet spot" associated with human speech/talking - therefore, perceived loudness is not exactly the same thing as sound intensity because we have these curves. - one thing that is fairly consistent is the threshold of pain at about 130 decibels regardless of frequency

ganglion cell types

M cells - do not respond to color - MOTION P cells - respond to color K cells - respond to color They all have different purposes, dealing w diff aspects of vision. Some respond to color

Where in the thalamus does auditory information go

Medial geniculate nucleus (MGN)

Individual differences in color perception

Monochromats: if you only have one type of photoreceptor. So rods only and no cones. Or one type of cone. This is very rare. Dichromats: if you are missing one of the three types of cones. Anomalous Trichromates/"color blindness" (most common): they have all 3 cones, but they have a deficit with how some function at particular wavelengths. (The deuteranomalous is the most common of the types of color blindness. This is a deficit in the m cone). Tetrachromacy: only possible for XX (females). Where they can have the genes and eventually lead to a functional 4th receptor. Many of these case studies are artists that paint in a diff way than how most of us perceive the world.

disorders associated with basal ganglia

Movement Control: - huntington's disease - parkinson's disease Coffee filter: its job is to hold coffee grounds to stay and allowing fluid to pass. ways it can malfunction (2): it can either not filter enough (lets coffee grounds through) or filters too much (liquid is not able to pass and overflows) Problems Basal Ganglia (2): 1. we can have too much getting through (relates to unwanted tremors we see with Parkinson's disease) 2. we can see problem of not enough going through (relates to trouble taking a step or initiating a happy smile with Parkinson's disease) Huntington's disease in the context of genetics & is a disorder with unwanted movement and its painful Choria symptoms Cognitive Control: - ADHD - OCD - some people suggest that these are issues with cognitive control where you focus too much on something or your task switching a little too much - there are some new studies linking this to the basal ganglia in both cases areas of the cortex are initiating the plan, the basal ganglia is like the middle manager "we have all these plans, which are we actually going to implement/execute")

What results from eyeball length

Myopia and hyperopia

are humans the only ones who have diff cortical representation of areas associated with them?

NO - For example: the eastern mole shows more representation for its snout and whiskers - the naked mole rat explores its world through its teeth so it gets overrepresents in its homunculus - the star nosed mole has finger like appendages on its nose that it used to dig and find food so those have an incredible representation in its brain in terms of finding the sensory feedback

Do photoreceptors produce action potentials?

NO! Photoreceptors produce graded potentials These are the ones that hyperpolarize in response to light, this is a graded potential NOT an action potential

Does everyone see colors the same way? What is associated with this?

No About 8% of male population and 0.5% of female population has some form of color vision deficiency: which we call Color blindness - this is sex linked. The genes that produce photopigements are carried on the X chromosome which is why males are more vulnerable

So are we constantly in one state of depolarization or hyperpolarization?

No We are rapidly alternating between the back and forth of depolarize, hyperpolarize, depolarize, not depolarize. - this pattern is how we transduce the sound, the rate and the intensity of the vibration is going to influence those action potentials as coded in the ganglion cells

What is perceived as noise

Nonrepeating waves Waves that do not repeat or have that periodicity. This is like the white noise that some listen to while studying to help mask distractions while studying.

Cochlea duct

One of the chambers in the cochlea. Filled with endolymph - highest amount of interest in when we are talking about how we perceive auditory stimuli - inside the cochlea duct we find the organ of corti (inner and outer hair cells)

Earbuds (dangerous?)

One of the most dangerous things for your ears (over the ears are better) - considered so dangerous b/c you get more battery lfe/higher volume so a lot of devices come with a warning - do not block outside noise as well, higher volumes to drown out noise (7-9 db) - speakers are smaller and closer to ear drum and louder at the same power level - average listening level as high as 110-120 db - teens with hearing loss up 33% since 1994 - american auditory society's rule is 60/60 - not more than 60 minutes at 60% of the maximum volume

Cochlear implants

Only treat problems that involve the cochlea - can happen through accidents or born with - somewhat controversial among deaf community b/c they are proud of their culture/skills/ASL/etc and some people see this as an attempt to remove that aspect of their identity - perception is a bit diff than normal sound (tech is getting better though). Described like mickey mouse talking underwater when first turned on. "Recognizable but distorted". With more experience it became less distorted, and more typical to normal perception

OSU rgb code

Our osu colors: scarlet and gray Scarlet: 153 in the long ("red) cone and 0 in both the medium ("green") and short ("blue") Gray: 153 in the long, medium, AND blue. - this can explain why the colors go so well together

Structures thus far

Outer ear contains the pinna and auditory canal. Then our middle ear has those two membranes, tympanic membrane, and the oval window. Between those we have the ossicles which amplify. Weak sounds, really quiet but annoying sounds, or help quiet really loud sound. Then we have fluid that moves into the cochlea and we have the organ of corti.

substantia nigra and parkinson's disease

PARKINSON'S (a disorder of movement control): we see that the substantia nigra shows a LOSS of cells that produce and release dopamine which results in motor side effects like the pill rolling, unwanted tremors, or difficulty starting certain types of voluntary movements - main symptom of parkinson's is that lack of dopamine that is going to the basal ganglia. we have talked about using L-DOPA as a treatment to get around this and reduce early symptoms "substantia nigra" = big black spot - this is b/c when dopamine hits the air and oxidizes it looks black, so if you have a high density of cells that have a lot of dopamine in them then they appear black

What is frequency theory? What is a way around its limitations?

PHASE LOCKING: this is when one neuron can fire at one distinct point in a period/cycle of sound wave and can essentially keep time with the vibration of the sound wave (frequency) - this is more applicable for lower frequency sound. If you have a higher frequency sound, one neuron is not going to be able to keep up with that as it is limited by its refractory period HOWEVER: the VOLLEY PRINCIPLE - you can recruit additional neurons to get around this. - we see the regular sine wave for the sound source as well as 5 diff neurons which are not firing at every cycle in the sine wave BUT they are firing at regular intervals that correspond to the same phase in the cycle. When the neurons work together, in total, we see that the total firing rate of the population keeps up with the rhythm of the sound frequency itself.

Primary Target of the optic nerve: Lateral Geniculate Nucleus (LGN) in Thalamus

PRIMARY: dorsal Lateral Geniculate Nucleus (dLGN) in Thalamus - got its name because it looks like a bended knee - 90% of the axons from the retina/optic tract are going to go - this is a specialized subregion in the thalamus - gets input from the optic nerve and has lots of diff outputs but the main one is the occipital lobe to be in the primary visual cortex (aka V1) for visual perception - we see 6 distinct stacked layer (like the 6 layers in the cortex) - @ the LGN we still keep input from each eye separate (important for organization) - alot of the input to the LGN is from the visual cortex which might help us modify what kind of info we can get based on our level of alertness and what is likely to wake us up if we are in the early stages of falling asleep

When does damage occur for hearing

Pain and possible permanent damage occur at 130 decibels (dB) EX. Machine gun fire, fireworks, airplane take off at 25 meters - so the threshold of pain is 130 dB

Cochlea ("snail shape")

Part of inner ear and has 3 different chambers that are stacked on top of each other: - vestibular canal (perilymph) - tympanic canal (perilymph) - cochlear duct (endolymph) which contains organ of corti These are filled with fluid (first 2 canals are filled with the perilymph whereas duct is filled with endolymph) Membranes: - Reissner's membrane separates vestibular canal; and cochlear duct - Basilar membrane separates tympanic canal and cochlear duct). Think the "bottom" b/c the basilar membrane is located at the bottom of the organ of corti - tectorial membrane. Think "roof" More of a gelatinous membrane over the organ of corti that helps increase the force on the hair cells

Types of auditory perception

Pitch and loudness perception

Perilymph

Pretty standard like extracellular fluid - its composition is similar to CSF (cerebrospinal fluid)

Transduction

Process of converting an external energy (like a wave or a touch) or substance into neural activity Ex. We had the light as the stimulus from the environment We had specialized sensory receptor cells (photoreceptors in the retina) Then, through a series of hyperpolarization and depolarization steps, we would eventually get to action potentials that could be read as code in the nervous system All sensory modalities do this, including hearing

Rods (photoreceptors)

RODS: used in a lighting condition called scotopic vision (dim light) - no color info (just black and white) and low acuity (low clarity, so the images from the rods are relatively blurry) - high density of the rods in the peripheral retina (not in the center field of vision) - 120 million photoreceptor rods in humans, this makes up about 70% of all the sensory cells in our body (vision is really important to us as a species) STRUCTURE: rods are long and skinny

Where do we compare the difference in arrival times in ears?

SUPERIOR OLIVE - arrival time and intensity of sound at each ear is analyzed by superior olive within the brainstem

What wavelength is the Maximum response for each cell type

Short cones (blue) = 420 nanometers Rods = 502 nanometers Middle cones (green) = 530 nanometers Long cones (red) = 560 nanometers These are parabolas, so even if it is not the peak frequency we can see that they still have some activation

Jobs of the cells in the visual cortex

Simple: respond to the orientation of lines Endinhibited: respond to corners/edges/movements - as we get into the further association areas beyond the primary visual cortex we will see some cells that respond to hands, or faces, or to jennifer anniston cells

Opponent process theory in terms of firing in the receptive fields

So we have the ganglion cell and we have a red on center and a green off surround. - when we have red light in just the center, this is when we have the most action potential - red light all throughout the field (on and off) is baseline - red light in the center, and green surround gives us the "cancelling out". It gives us the darkness condition that we see when no light is shone

NFL trouble regarding color anamolous (color blindness)

So, the NFL has diff uniforms and they had a game of red vs green uniforms. They both had helmets with a stripe on it. And remember that males are more likely to have color anomalous vision. So lots of men in the audience had no idea who had the ball because there was no contrast between any of the players. - the NFL made a rule that one team must always be wearing white, because you can't have color being the only source of information. Making sure everyone can see in some way

secondary target of the optic nerve: Superior Colliculus in midbrain

Superior Colliculus in midbrain - important for visual reflexes and guiding our head/eye movement Ex. If someone throws a ball right at your head and you need to know whether to duck and take cover - about 10% of retinal axons - responsible for the damage to the occipital lobe that creates blindsight

Secondary target of the optic nerve: Suprachiasmatic Nucleus in the hypothalamus

Suprachiasmatic Nucleus in the hypothalamus - some small branches of the optic nerve that goes to a part of the hypothalamus (right above the optic chiasm) - this is the area that responds to light in terms of setting our diff biological rhythms (regulates sleep/wake cycle) - small number of retinal axons - responsible for the damage to the occipital lobe that creates blindsight

Which targets of the optic nerve are responsible for the phenomenon of blindsight in the occipital lobe?

Suprachiasmatic nucleus in the hypothalamus Superior Colliculus in midbrain

Teen buzz ringtone

Teenagers thought this was cool for a while because they could have notifications come on their phone and their old teachers wouldn't know - around 17,000 Hz. Really annoying if you can hear it

Sound vibrations are transferred from ...

The air of the middle ear to the fluid of the inner ear

What is the center of the cochlea called

The apex - the center of the "snail shell" - Waves travel backwards along the tympanic canal from the apex to the round window (another membrane) that bulges out so we can release the pressure of the vibrations

What is the cranial nerve that the hair cells follow in the auditory pathway

The auditory cranial nerve (CN 8)

Medial geniculate nucleus in thalamus (MGN)

The axons from the inferior colliculi synapse (in the midbrain) go to the medial geniculate nucleus of the thalamus (MGN) - the MGN then projects to the main auditory cortex (A1) ***Look at pathway pic

Receptive fields in the Lateral Geniculate Nucleus (LGN)

The circular receptive fields (in the bipolar/ganglion cells) found in the retina are replaced with elongated "stripe" receptive fields in the LGN - the circular receptive fields are going to be stretched and replaced with stripe receptive fields in the cortex - the visual cortex has about 200 million cells which tells us we are going to see lots of specialization where the cells are going to respond to certain aspects of vision corresponding to the visual field

What is an aspect of vision that does not support the trichromatic theory

The color afterimages that we see - for example, if you stare at the yellow/green flag, you will see the regular red/white/blue flag after This happens when the cells get "tired" and their opposite still had lots of energy so you were able to see the results of it as diff colors. You are looking at an image that is technically not there. - afterimages are explained best by the opponent processing theory

Which receptive fields are the same between the on surround and on center

The dark and the all light conditions are pretty much the same

Ossicles

Very tiny bones in the middle ear - these help amplify the sounds and transfer vibrations from air to fluid Ossicles are a collective name of 3 bones in the middle ear. - malleus (hammer) - incus (anvil) - stapes (stirrup) Latin name (common english name) These are the smallest bones in your body. They are very important for our hearing

Explain the process of depolarized and hyperpolarized hair cells

The fact that we are in endolymph is important b/c it has a much higher concentration of potassium. - we are opening potassium channels b/c it is in much higher concentration in this fluid. K+ has a positive charge. The K+ is still driven in to get into the more negative cell, but now the concentration forces are in agreement so the k+ wants to go in. - these are mechanically gated channels because the tip links are basically going to pull them open and allow K+ to flow through - so as we are vibrating in the fluid, the hair cells are going to move back and forth (like seaweed in the ocean) Depolarized: - the force of the tectorial membrane causes the fluid to move in one direction (middle pannel) there is more tension on the tip links, mechanically gated potassium channels open: influx of K+, depolarization occurs, opening of Ca2+ channels, more glutamate is released, and more action potentials in the spiral ganglion Hyperpolarized: - But since it is a vibration, we go from the forward direction to the backward vibration where there is no tension on the tip links which results in all of the mechanically gated K+ channels to be closed. There is no depolarization, no glutamate and there is a reduction from the baseline rate of action potentials

Emmetropia (good)

The happy condition of no refractive error and everything is focusing and bending the light in just the right way so that it focuses right on the fovea. - focuses on the fovea. 20/20 vision: if you are 20 feet away, you can perceive the object as if you are 20 feet away

What are the specialized receptor cells for the auditory pathway

The inner and 3 outer hair cells in the organ of corti (the base of these cells are in the basilar membrane of the cochlea)

Patellar tendon reflex

The knee jerk - described as a monosynaptic reflex, it is very close to one synapse but CAUTION it is slightly more than one synapse - usually a hammer that creates a bit of pressure on the patellar tendon which has a sensory feedback system that determines the stretch, the sensory pathway (afferent) goes through dorsal root ganglion, there is then a couple of synapses interneuron (one neuron that is not sensory or motor it is just neuron to neuron communication) and a synapse that is excitatory causing the muscle to contract and causes our leg to kick out WHY kicking? - if something is coming in damaging our knee and our ability to walk, kicking it away is one of the safest ways to stop that damage from happening It is not monosynaptic b/c there is another motor neuron synapse that is typically inhibitory b/c muscles work in opposite paris, so by exciting one muscle and making it contract you need to inhibit the other muscle so they aren't fighting each other and it can relax and not have that contraction - mediated completely in the spinal cord and it's involuntary b/c we don't have conscious control over this process So a sensory neuron, interneuron, and 2 motor neurons (one excitatory and one inhibitory)

Where is the point of descussation in the visual system? Hearing?

The optic chiasm Hearing: brainstem

What is the cranial nerve that the photoreceptors follow in the visual pathway

The optic nerve (CN 2)

Importance of ossicles: strong sounds

The ossicles are connected ot a couple of muscles called the tensor tympani and the stapedius. Once these muscles are tensed, it's going to reduce the ability of the ossicles to move and vibrate - so it is a way of muffling loud sounds and hopefully protecting the inner ear - not a perfect system. They are delayed by 200 ms. (Takes a little while for it to kick in and do its job ). Ex. Those people in movies who walk away from explosing all cool like; they should have resulting ear damage from that - the tensor tympani and stapedius muscles are also tensed when swalloing, talking, and general body movement Ex. when we are speaking we have the tensor tympani and stapedius muscles are tensed a bit so the auditory perception of our voice as we are speaking is diff than when we are listening to a recording when we do not have those muscles tensed. Everytime we listen to a recording of ourselves it is weird and some don't like it.

Pinna

The outerportion, what most people call the "ear", the fleshy bit. - collects, focuses, and localizes (where sound is coming from) sound. Especially on the vertical plane. - signals emotion in some animals. In some species, the pinna has efferent (exit) connections so it has motor control and you can change the position of the ear to signal emotion. Ex. Dogs who have droopy or perky ears. If a dog pins its ears at you it means they are mad. Ex. Let's say you wanted to signal someone from far away that you couldn't hear, what gesture would you use? You'd cup your hand behind you pinna. This is actually useful, because the act of cupping is going to increase you pinna and make it easier to hear weak sounds The flexible outer flap of the ear which channels sound waves directly into the ear canal.

Lateral inhibition

The pattern of interaction among neurons in the visual system in which activity in one neuron inhibits adjacent neurons' responses.

What are the specialized receptor cells for the visual pathway

The photoreceptors (rods/cones)

Processing by retinal interneurons

The photoreceptors communicate and send their neurotransmitter/messages directly to 2 diff group of cells: HORIZONTAL CELLS - integrate/combine information from photoreceptors that are located really close to one another - communicate through graded potentials with bipolar cells BIPOLAR CELLS - they get information from photoreceptors OR from the horizontal cells - 2 categories: diffuse: very big, from the periphery of retina meaning it is from RODS, we see a lot of rods converging onto one diffuse bipolar cell midget: smaller, from photoreceptors in the fovea (meaning they get their information from CONES and are associated with color), we see one cone will go onto one midget bipolar cell (contracting 2 total cones) - this is a reason why our most detailed vision comes from our cones: b/c of the idea of keeping it small (one cone to one midget bipolar cell)

depolarization

The process during the action potential when sodium is rushing into the cell causing the interior to become more positive. - voltage gated Na+ channels open, this is when the membrane is most permeable to sodium

Endolymph

The ratio of ions is not what we would typically see. - has a high concentration of potassium and a very low concentration of sodium - since the different fluid is very high in potasium relative to the surrounding cells, the activity acts funky (diff than you would expect)

The dark current (RODS)

The resting potential of a rod outer segment in complete darkness is about -30 mV. This means the photoreceptors are relatively DEPOLARIZED (more positive) than typical neurons whose resting potential is about -70 mV - this is because the sodium channels are kept open by a compound called cGMP (this is a second messenger). Its job is to keep open the sodium channels, so in the DARK we see sodium flowing in - when light is present, the structure of rhodopsin changes from bent to straight (light breaks down rhodopsin), this then releases enzymes that breaks down cGMP (taking away the doorstop that was holding the sodium door open) - when we take away that cGMP, fewer sodium channels remain open (less positive sodium ions flowing in) and receptor hyperpolarizes SO in the dark, we are relatively depolarized at -30 mV, THEN we turn the light on and get more negative at -60 mV which is hyperpolarized

Sound as a stimulus? How do we perceive loudness? Pitch?

The sound stimulus takes the form of waves of vibration (ex. Waves through air or liquid) - these are compression of these molecules that we perceive. - The amplitude (height of the wave) is how we perceive loudness - the frequency (distance from peak to peak/wavelength) is perceived as pitch - pure tones feature a single frequency and have a pure sinusoidal wave. Pure tones are those that are usually annoying sounds like alarms or beeps - complex tones: produce timbre (multiple frequencies nested in). There are most of the sounds that we listen to. - nonrepeating waves are perceived as noise (waves that do not repeat or have that periodicity)

Oval window

The sounds from that were at the ossicles then push on the oval window. This causes the fluid inside the cochlea to move back and forth which activates hair cells to also move back and forth. This allows us to hear. Oval window: leads to the cochlea. This is where the ossicles are going to put their peressure (which becomes vibrations) on

Which muscle specifrically pushes on the oval window

The stapes. This causes vibration to happen in the cochlea

What are the primary colors

blue, green, red

the visible spectrum

The tiny part of the electromagnetic spectrum to which our eyes are sensitive: 400-800 nanometers - the shorter wavelengths are towards the blue ends of the spectrum, the longer wavelengths are towards the red end of the spectrum - there are lots of species can see outside of this range. ex: bees/butterflies can see in ultraviolet light which highlights the central area so they know exactly where to go to find food - there is some evidence that snakes and reptiles can use infrared vision to help them locate the body heat of their moving prey

Sound frequency

The wavelength of a sound wave - measured in cycles per second known as Hertz (Hz) - humans have a large hearing range. From 20-20,00 Hz - Infrasound refers to frequencies below the range of human hearing. Infrasound is used commonly by really large mammals like elephants/whales. just like there were visual stimuli outside of our visible spectrum, there are also auditory frequencies that are outside the range that humans hear. - ultrasound refers to stimuli with frequencies beyond the upper range of human hearing which is used commonly by rodents (like mice). Rodents actually have ultrasonic vocalizations when they laugh. Bats/dolphins use ultrasonic waves as part of their echolocation proceses.

Importance of ossicles: amplifying weak sounds

Their biggest role is for amplifying weak sounds. - Ossicles have hinged joints that gives them the property of levers to amplify sounds - they amplify vibrations (sounds) by a factor of 20x -the stapes has a smaller surface than the malleus, so sound energy is concentrated. So we concentrate/focus the vibration on the points of those bones - generally, our outer ear is filled with air, but our inner ear is filled with fluid. It is harder to make fluid vibrate than air vibrate so we have to amplify the vibrations so we can move that fluid inside the cochlea - the inner ear consists of fluid filled chambers, thus it requires more energy. Amplifying weak sounds is the main purpose of ossicles but is not the only thing they do

Distribution of rods and cones

There are no rods in the fovea, only cones. Rods predominate outside of the fovea Cones are found exclusively in the fovea - the optic disk has absolutely NO photoreceptors (no rods/cones)

Lateral inhibition illusions: Hermann grid

There are some optical illusions and how the system can go wrong - the Hermann grid: you can see a gray area at the crossways of the white lines. This happens b/c light in the center excites the on center cells and at the intersection there is more surround inhibition which decreases the center mediated excitation which causes the intersection to appear darker. So you are having a different perception than is real

How do cochlear implants work

There is a receiver outside the head that captures the sound and turns it into a digital ones and zeros binary code which has a battery that powers it over time There is also a processor that transmits the digital signal through the head into the sound coil inside the head in the implant that converts the digital sound into electrical impulses These stimulate the auditory nerve directly bypassing the cochlea and following the central auditory pathway where it is processed as sound

While visual fields were processed almost entirely contralaterally....

There is more ambiguity in the auditory system. - most of hearing, though, is processed contralaterally which means that sounds in your left ear are processed mostly in the right side of the brain (right auditory cortex) - descussation (the point that the signal crosses over) is in the brainstem. At the point of the medulla going over to the superior olive is where the fibers are going to have their crossing over - a small number of tracts remain ipsilateral which is used for comparison purposes to help us find the localization of sound and orient towards the source of the sound

Conceptualizing a receptive field for the bipolar cell

These center surround receptive field diagrams correspond to a chunk of visual field that is relatively small and all the diff receptive fields are going to be how we map some of the vision that we actually see the antagonistic center surround organization is found in bipolar cells, remember that bipolar cells can have 2 diff inputs from photoreceptors directly and horizontal cells asking "what is the receptive field on this particular bipolar cell": The center: where we get the direct input from the single set of photoreceptors. The surround: where we get the indirect input from horizontal cells connected to photoreceptors RECEPTIVE field can be described as being on center OR off center On center: lights in the center, this is stimulatory/excitatory, light causes the most depolarization in the center of the bipolar cell. So if it is an on center then you know it is an off surround Off center: where the center is inhibitory, but the surround is excitatory. So if it is an on center then you know it is an on surround

Owls in localization by comparing arrival time in superior olive

They are excellent at this and have the best adaptations for localizing sound difference -the way their feathers are around their face funnels the sound right into their ears. Their ears are closer to their eyes than ours. They do not rely on vision, but they rely on sound to find their prey. - if the sound source is immediately in front/behind, the cells in the superior olive get the signal at same time (no shifting balance) - if sound source is at a diagonal angle, we see a slight diff in timing in the superior olive cells, which shift it towards one side and orient the owl to the source of the sound

Enchroma glasses

They claim to improve color vision in people who are color anamolous (color blind) - they filter out some wavelengths so they make the differentiation easier for them - the effects are remarkable ONLY if you have a specific type of color anomalous vision that is most common

What backlash did hubel and wiesel receive

They got backlash from the scientific community as they said "these cells are so complicated, how dare you call them simple and demean them" and "yes your complex cells are great, but I'm sure we have just scratched the surface of what the visual system can do" - Hubel and Wiesel got irritated b/c of this and so they named the next group of cells they characterized "blobs" to avoid any possible connotations

Qtips

They have a label warning people to not put them in their ears, yet we do. Technically, humans aren't supposed to clean their earwax as it is selfcleaning

Top down processing

Think of your brain influencing lower structures. This is when your expectations/memories/hopes/biases shape what you are experiencing - expectations influence our perceptual experience Ex. When someone tells you information about something. She tells us that the image is actually a dalmation so now we are looking for it in that way.

Types of processing strategies

Top down processing Bottums up processing - these are not either or. We often use both of these at the same time and we often do when we are perceiving stimuli

Cataracts

Typically occur with age, but can happen to anyone. our lens which is normally transparent and allows light through with no problem, becomes cloudy and this scatters the light so it is not able to focus on the fovea. - you can see that cataracts are visible looking at the eye itself - can be treated surgically with silicone implants

The dorsal stream ("where/how")

Visual analysis beyond the primary visual cortex - has a slightly upward trajectory from V1 (dorsal = top of brain) - called the "where/how" pathway: knowing where something is, or projecting where it is going to go if you are looking at a thrown object, or how we use something. Ex. This area is important for knowing how to grasp an object and how to use it/interact with it. (Grabbing a water bottle from the side instead of from the top) - it has an important role in processing MOTION - areas MT and MST (medial temporal lobe) are involved in motion processing, if there is damage in these areas nsomeone can display a coniditon called akinetopsia Akinetopsia: fairly rare conditon, (without, movement, vision) so instead of life being in real time like a movie it would be like a series of photographs - imaging trying to fill up you water glass if you can't perceive motion. Imagine trying to cross the street if you can't perceive motion. Very impairing.

hubel and wiesel who won the Nobel Prize for

We noted the receptive fields of V1 cells and how we change from being a circle (in retina) to being stretched out (in V1 cells) - most of what we know came from these guys who won the Nobel for their work in characterizing the V1 cells of an anesthetized cat - they were trying all these diff dots of light and darkness trying to find the stimuli that excites it, and they were recording from cells in the cats V1 area and it was hooked up to a speaker (every time there was an action potential there was a popping noise). One of their slides in an old school transparency projector got stuck and as they were trying to jiggle it, it created the appearance of a line which made their speaker go crazy with action potentials - this led them to change their stimulus into looking at the lines rather than just the dots, so they found and characterized diff cells ( simple, complex, and blob cells)

Hyperopia (far sightedness)

When light entering the eye is focused behind the retina. - light overshoots the fovea, it actually projects to a point that is past the fovea - they can see far away, but it ishard to look closely - reading glasses are appropriate

Myopia (near sightedness)

When the light entering the eye is focused in front of the fovea/retina and distant objects cannot be seen sharply - it is focusing in the vitreous humor (gelatinous fluid filled area) instead of the fovea - you can see things up close, but not far away

When do we see the biggest difference in arrival time of sound from ear to other ear

When the sound stimulus is directly next to the ear - when the sound is directly in front or behind the head there is no difference - angles between this is what we see in our days most. We compare that distance from the far ear and the near ear to know which way to orient

Myopia correction

When we have glasses/lenses it changes the way that light is refracted so that it focuses on the fovea where it is supposed to. - concave lenses

What does on center or off center tell us?

Where the most depolarization is in the bipolar cell

Is it possible to hear/utilize the auditory frequencies outside the human range?

Yes. - ultrasound is used in terms of prenatal imaging looking at a fetus. It is also used in many other applications like looking for blood clots when we want to have a noninvasive and safe ways of imaging tissue that we can't directly see, - there are some suggesting that infrasound can be weaponized. There were many headlines coming from Cuba that diplomats were getting sick and having really strong headaches/nausea/mysterious injuries. They started suspecting an ultrasound attack (no evidence of weapons that could do this).

brain machine implants

a Columbus kid (Ian B) had an injury that rendered him quadriplegic (only moving his shoulders around, nothing else) and he has been part of a study at OSU where he is using a brain implant to regain some of his motor control - has made remarkable progress, can move his hand after 3.5 years! - signals from brain in the motor cortex area are in tact but the signals arrive at the injury in the spinal cord and are completely blocked so they can't get to his muscles which means he can't do movements - deciphering signals in brain that are associated w/ hand movement. they placed an implant into motor area of brain with a connector secured to the skull which acts as a window into Ian's neural activity. - once the system is connected, they show specific images of diff types of hand movements, they then record the signals associated with those movements from the brain and learn how to decipher them - basically when he is thinking about doing the movements, they see the areas of the brain that light up and focus on those signals in a computer system. this system is then connected to another device on the arm that provides signals for the muscles of forearm that drive hand and finger movements - he has regained even fine motor movement just by using his own thoughts

white light

a combination of all the colors of the visible spectrum

four eyed fish

a fish that needs to see what is happening below and above the water - t is called 4 eyed fish because it has 4 separate pupils, 2 in each eye, one above and one under the water - this is so it does not have to deal with the problem of refraction and see what is happening in diff aspects of its environment

Tectorial membrane

a gelatinous structure, attached on one end and is free on the other end. - It basically floats just above the hair cells. Is a way to increase the shear force on the hair cells b/c moving is what allows the hair cells to open - that extends into the middle canal of the ear, floating above inner hair cells and touching outer hair cells

Limbic system

a group of structures that play a role in emotions LOCATION: more off to the side, starts midline then curls out more laterally (particularly, some are in temporal) - these structures are grouped together is b/c they are so interconnected with each other. they are receiving inputs and sending outputs from/to other structures in the system which is why they are connected forming the functional circuit MAIN STRUCTURES: hippocampus, amygdala, hypothalamus, Anterior cingulate cortex (ACC), and posterior cingulate cortex (PCC)

Receptive field

a location on the retina at which light affects the activity of a particular visual interneuron - any bipolar cell receives input from one or several photoreceptors located in a specific area on the retina, that area is referred to as the interneuron's receptive field - you can think about the retina as an overlapping mosaic of receptive fields - if a pinpoint light is directed to the retina it is possible to identify which interneurons are responding to the light by recording their activity. A light stimulus must fit within a cell's receptive field to influence its activity. The cell is "blind" to any light falling outside its receptive field on the retina

Wernicke's aphasia (temporal)

a person has the INTENT to say something clear, like "I want an apple" but they end up saying something like "marble yelleen I him gophratic" - therefore there is a mismatch between the intention and the actual meaning - people with damage to this area of the temporal lobe will speak a lot but it will be very hard to extract any meaning from it and communicate in any useful way

procedure regarding Corpus Callosum

a procedure still used today cuts the Corpus Callosum in half to prevent the spread of some very severe forms of seizures - those that have this cut in half are pretty normal in daily life, it is only when very specific experiments where researchers separate the visual field from left to right hemisphere do they see any type of abnormalities in their function (meaning there aren't significant effects)

encephalization quotient

a ratio of brain size relative to body mass - the size of a human's brain compared to body size beats out the EQ of other species which is why humans have the most advanced brain - dolphins come in second

Brodmann's map

a very well known cytoarchitectural map map of different parts of the brain - made by a german neurologist who divided the cortex into 52 areas - he did this by looking at micrographs of what the cell bodies were in each area, how they were organized, the shape, the type of cells (called cytoarchitectural map) HOWEVER - some recent work looking at some of the funcitonal connections (not just structure of what cells look like) but what areas are active at the same times during functional pathways. using fMRI and DTI tech they say 180 areas. - so some say they want to break down more sub regions while other say larger regions/more commonalities (more or less)

Walter Freeman

advocate for the lobotomy - goes in behind the eye using an ice pick/hammer to essentially cut off the prefrontal cortex from the rest of the brain - this was particularly applied to patients with schizophrenia but in the 1940-50s they were institutionalized in mental hospitals - used on patients who were difficult to handle, and it calmed them down substantially - they were described as emotionally blunted, highly distractable, childlike and once we developed antipsychotic medications we decided it was a bad idea to do permanent brain surgery to treat psychopathic patients WE DO NOT DO THIS ANYMORE - we used to think it was a good idea though, some advocates even received the nobel prize

secondary consequences of injury

after an injury we see a point of injury as well as spreading damage (if it fits in just the right place then it can be the difference in maintaining sensory/motor function of critical area or not maintaining it - there is the primary injury and then an area around is the secondary injury. there is then a ring of astrocytes that form around the injury trying to help but they create a thick impenetrable scar tissue that we can't get past. the microglia come in due to the signs of cellular damage, and if it shifts to too much of an activated state then they can start damaging/attacking healthy neurons which can affect the surrounding myelination - so even if we have a specific point of injury, we see alot of secondary consequences spread beyond that initial point of injury which is why quick treatment would be important for something like spinal cord injury.

frog, goose, human brain evolution

amphibians were around first, then birds, then humans - the biggest difference is the growth and expansion of humans' cerebrum compared to the other species - COSI's dinosaur skulls which are related to modern bird species, how the brains of birds now could have fit a dinosaur brain then

thalamus: gateway to cortex/sensory switchboard

appears in 2 halves just like other brain structures - receives sensory info and regulatory info - described as being a gateway to the cortex b/c it is a source of lots of converging inputs. most of the cranial nerves (except smell) that had sensory functions had one of their targets in the thalamus. so sensory input goes to the thalamus and then it directs the signal to the appropriate sensory region of the cortex ex. how vision comes in through optic nerve goes to specific area of thalamus and is redirected to visual cortex in occipital lobe is also called "sensory switchboard" b/c when phones had wires and there were operators they had to move wires to connect the call. the thalamus is not moving connectiond but it's changing which connections are active. like a post office hub, info comes in and thalamus redirects it to other processing centers

what color is an apple?

as white light hits an object, only one color is typically going to be reflected - we see the color that is reflected, all the other wavelengths are absorbed by the object - so when you say what color is an apple, it is actually everything but red because red is the only color that reflects back

white matter

ascending and descending tracts

embryological growth of brain

bottoms up - starts with the hindbrain and then works its way up to the midbrain then forebrain

Paralysis? how to determine how severe it is?

can happen when damage to the spinal cord happens - severity depends on the location of damage. the higher the injury on the spinal cord, the more function is going to be lost. - everything below the point of injury is considered at risk b/c it is going to have a hard time bringing the sensory info up to the brain, everything below the point is not going to have the motor outputs coming from the brain going to its targeted muscles/organs

optical functions

capture light and form detailed spatial images (allowing us to see)

gray matter and its prominence

cell bodies - dorsal horn is where we get the sensory input - ventral horn is where we get the motor output for voluntary movement or spinal reflexes most prominent in: - these are big/thick in the cervical (narrows in thoracic) comes back out in lumbar (narrows in sacral) the dermatomes in that are connected to the spinal peripheral nerves in the cervical/lumbar which get the sensory info from the arms. there is also more motor output b/c of muscles in arms/hands that needs to be controlled compared to the thoracic, there is not much sensory feedback coming in b/c we do not go around chest bumping into the world/using that sense of touch to explore things - there is not a lot of motor control as well as the main muscle we use in the thoracic is the diaphragm for breathing but it is not nearly as many muscles as it is with our arms/hands

spinal cord sections

cervical (neck area) thoracic (chest are) lumbar (lower back) sacral (by tailbone) coccygeal (the tailbone) = correlate to the total 31 spinal nerve - these outside of the spinal cord nerves swell to form the spinal ganglion (also known as the dorsal root ganglia which contain the cell bodies of sensory neurons, afferent, entering the cord at that region)

chordate vs nonchordate

chordate = vertebrate (a rat, monkey, humans who have brain/spinal cord organization) nonchordate = invertebrate (no true brain/spinal cord. instead it has several diff processing areas called ganglion.) we can map that more simple nervous system and see some of the connections with activity - chordate nervous system: spinal cord is on the dorsal side whereas nonchordates have their ganglia on the ventral surface of the animal

iris

colored area; contains muscles that control the pupil

marshmallow test

delayed gratification - bring kid into room and give them a choice: one marshmellow now or wait and get 2 - this is a test that measures your ability to delay your gratification (to wait for a reward that is better)

dorsolateral prefrontal cortex

dorsal = towards top lateral = side (like where horns are) of the frontal lobes - many reciprocal connections with limbic system, basal ganglia, and other parts of cortex. these structures send pathways to the dorsolateral PFC and then it sends it back - many inputs and outputs, processing hubs - involved in executive functions LIKE: attention, working memory (solving peoblem/manipulating info), goal directed behavior (Phineas gage struggled w this after accident) - Reduced activity in schizophrenia

afferent nerve

dorsal sensory body to CNS

Tympanic membrane

eardrum. Membrane that vibrates in response to the patterns of compressed air/liquid molecules otherwise known as sound waves. - the movement begins the process of transduction of sound waves into action potentials

fissure

especially large sulcus - often an antomical landmark ex. the fissure that divides the frontal and temporal lobe

spinal cord damage and hypothermia

hypothermia = lowering body temperature, this has become a treatment - this was based on the observation that if people got a neck injury by diving into a really cold body of water (? if people had a neck injury and they were diving into cold water) , they seemed to have a better outcome than people who injured their neck by diving into warmer water - a controlled study in animals: they injured the animal spinal cord in a controlled way and after the injury they were kept at either their normal temperature of hypothermic in blue group. they then monitored the animal's recovery using a marker for locomotion. we see the hypothermic animals showed a better improvement. they. they were also the only ones to cross the threshold of having some movement recovery compared to the normothermic group

10% of brain MYTH

i.All areas of the brain are shown as active even when doing simple tasks like making breakfast ii.The brain uses 20% of the body's energy, which would not be the case if we were only using 10% of it iii.Brain mapping shows that all areas of the brain have a function iv.If we only used 10% we wouldn't have such a large brain

the Babinski reflex

important developmental and diagnostic purposes - when you stroke the bottom of a patient's foot they check for paralysis using this babinski reflex - they come around the outside edge and curl in on a particular neural pathway - a healthy adult curls down the toes (can't control it) - that same stroke in an infant would cause the toes to fan outwards which is called the Babinski sign, they might laugh as it might be ticklish - before a child can walk they show the toes fanning outwards, once they learn how to walk they shift to toes curling - we think this is b/c we need to have that maturation of the descending circuits for inhibition to change that normal reflex (the Babinski reflex occurs in the absence of descending inhibition) - if someone is paralyzed (damage to spinal cord) they revert back to the infant state and show the toes curling out, so they look for that as a part of the diagnostic procedure

lizard brain (INACCURATE)

in context of popular media "when you are acting really afraid/aggressive your lizard brain/reptilian brain" is being active" - this is from a theory in the late 1950s/1960s and does not correspond to the brains anatomy. it was NOT a part that only reptiles had - inaccurate/not the most accurate way to divide the brain

retina

innermost layer in back of the eye where light is converted to neural impulses. - contains visual interneurons (important for visual processing steps) and photoreceptors (respond to light) - optic disk (blind spot), this is where all the blood vessels converge and leave - macula: shadowy area, like a pit along the relatively flat retina, at the very center of the macula is the fovea - the fovea is the focal point, most detailed and clearest vision, corresponds to the center of your field of vision ex. what your eyes are focusing on right now is in the center field of view (CENTRAL vision) but there are things around you that you are not really looking at off to the side (PERIPHERAL vision) humans do not have: - tapetum lucidum which is found in mammals that are better than us in night vision. the reflective quality allows for improved night vision ex. when you're driving and see the reflection of your headlights in a raccoon's eyes. this is the tapetum lucidum

What photopigment is found in cones?

iodopsin - requires a lot more light than rods in order to respond (which is why we need this in bright daylight and our bright artificial lighting conditions) - humans have 3 different cone types: BLUE/short, GREEN/middle, and RED/long wavelengths

midbrain functions (subregions)

is unique in that it is the only structure in the mesencephalon! SUBREGIONS: - periaqueductal gray: natural pain management, endorphins. it is around where the CSF and the ventricles will flow through (the aqueduct), it is the area that has some of the highest density of endorphin receptors in the entire brain (endorphins are a neuropeptide associated with pain relief in the context of the runner's high) - red nucleus: motor output pathway (part of the circuit that allows the eyeblink to happen in eyeblink conditioning) - substantia nigra: one of the major dopamine releasing areas in the entire brain (it primarily release into the basal ganglia). it is clinically significant in terms of Parkinson's disease AND this region is involved in motor output - Superior and inferior colliculus: the SUPERIOR colliculus is associated with where your VISUAL gaze is focused and reacting to new stimuli the INFERIOR colliculus is associated with AUDITORY reflexes like when someone shouts your name and you do that spin move to figure out who is calling you

Sulci (sulcus)

lowered areas = valleys - appear like shadows in pictures sulci = singular sulcus = plural

the central sulcus (precentral, postcentral?)

major dividing line between the frontal lobe and the parietal lobe precentral gyrus: in the gyrus in front of the central one (part of frontal lobe) is where we see the primary motor cortex postcentral gyrus: part of parietal lobe, where we see our primary somatosensory (touch) area

motor humunculus

map of the primary motor cortex in relation with how much brain space diff parts of the body receive humunculus = little man - hands and mouth are most overrepresented, we have the most motor control in these areas - these areas are also important for eating and getting food into our mouth accurately as well as communicating which is why we have the most cortical representation/control in these areas

sound intensity

measured in decibels (from alexander graham bell, the original inventor of the telephone) - measuring in decibels is a logarithmic scale. So differences at the low end of the scale are going to be perceived as very small, but as we get higher the differences are going to vary by a factor of 10 billion in terms of intensity (humans perceive sounds that vary in intensity by a factor of over 10 billion) Ex. Raindrops in quiet room = 40 db whereas a lawnmower = 90 db - the threshold is defined as a sound that is perceived more than 50% of the time (0 decibels which is like a fly wing flapping near your face). So it shows a better than chance reliability at saying i hear this/i don't hear this. - pain and possible permanent damage occur at 130 dB

Where is the hippocampus located?

medial temporal lobe (part of limbic sytem) - fairly small - has an interlocking C's shape. even the mouse shows that same organizational pattern of the interlocking C's. if you zoom in, you can see that the hippocampus has a clear organizational flow of info - one of the few brain structures that has a detailed start and ending point/linear progression of connections

transition point between spinal cord and brain (stem)?

medulla - the spinal cord extends from the medulla to the first lumbar vertebra

what is the order of the hindbrain (otherwise known as brainstem)

medulla, pons, then cerebellum

Hyperpolarization

membrane potential becomes more negative than resting potential - this occurs because the voltage gated K+ channels stay open a little longer than necessary, so the inside of the cell is losing more and more of the positive K charge

midbrain segments

mesencephalon

The volley principle

multiple neurons can provide a temporal code for frequency if each neuron fires at a distinct point in the period of a sound wave but does not fire on every period - each neuron is doing its piece to contribute to the total representation of the sound wave which allows it to be a higher frequency b/c we are less limited by the refractory period as they are working together ("volley")

where is the white and gray matter in a myelin stain?

myelin stain = white matter will be darkly stained on the outside of brain (myelination occurs at the axon which is white matter) butterfly shape/gray matter will be lighter in the middle b/c this is where the cell bodies are

layers of cortex and axon tracts

myelin stains show us that deeper layers of the cortex have more axon tracts - so layer 6 has more axon tracts than layer 1 which develops last (bottoms up)

What is the hypothalamus part of

the diencephalon as well as being connected to the limbic system

Place theory of Pitch Perception

neurons associated with a specific place in the cochlea are going to respond preferentially to sounds of diff frequencies HIGH frequencies/pitch = proximal end of cochlea, near the oval window, (the starting point where it is thickest (?)) LOW frequencies/pitch = distal end of cochlea, near center/apex of coil, (where it is skinniest (?)) - as we age we generally lose ability to perceive higher frequencies. Think about a path of grass (hair cells), at the beginning of the path the grass is most likely to get trampled and worn down. This is what we see with high frequency: those hair cells at the beginning are most likely to be damaged by chronic/severe noise throughout life If you unroll the cochlea we see that the thickness/diameter of the basilar membrane is diff from the starting point to the ending point (apex/center)

is having a bigger brain better?

no - there are many species that have a bigger brain than us like elephants or whales but aren't necessarily smarter than humans - humans have a much higher EQ than other animals - ex. whales' cognitive skills are way lower in comparison to humans

is there only one structure involved in motor control?

no! there are many! - cerebral cortex - basal ganglia - cerebellum - thalamus - brainstem - spinal cord - muscle

orbitofrontal cortex (OFC)

on the bottom portion of the frontal lobe, Located above and behind the eyes closest to the nose area - this area is associated with impulse control, resisting urges (doing what you should do not necessarily what you want to do) - delayed gratification - responding emotionally to bad choice (if someone makes a terrible decision you'd expect them to feel mad/sad etc but if someone has damage to their OFC they are indifferent and don't care)

Frequency theory (temporal code) of pitch perception

on the top trace, we have the wave representing our sound stimulus. On the bottom, we are tracking the firing rate of our neurons (likely spiral ganglion) Interesting: the firing rate of the neurons is highest when we see a specific phase in the wave. The neural firing rate shows rhythmicity just like the sound wave. - we also see illustration of sensory adaptation. The first firing rate is the highest, at the point where the stimulus first presents. Then it gets weaker and stabilizes over time PHASE LOCKING: this is when one neuron can fire at one distinct point in a period/cycle of sound wave and can essentially keep time with the vibration of the sound wave (frequency) - this is more applicable for lower frequency sound. If you have a higher frequency sound, one neuron is not going to be able to keep up with that as it is limited by its refractory period Similar to color perception in vision

Parts of the ear

outer ear, middle ear, inner ear

cornea

outer surface of the eye. curved, transparent dome that initially refracts/bends incoming light

overview of eye structures

outermost surface of the eye (what you touch if you put your finger in your eye) is the CORNEA - it has a fluid filled area behind it called the anterior chamber (the cornea AND the anterior chamber are points of refraction) - the hole in the iris, pupil is black spot in center where light passes through - the rystalline lens is solid and changes its shape to help us see things near or far, is another point of refraction - the bulk of the eyeball is a fluid filled chamber called the vitreous camber (another point of refraction) - the retina is the back membrane, this is where the cells that respond to light is located - the fovea is the focal point, the ideal place where light is focused and where we have the most detailed in our color vision SO light is going through many diff points of refraction before it is ideally focusing on the fovea - optic nerve (cranial nerve 2) and the blood vessels leave the area at the blind spot where there aren't any photoreceptors

fovea

part of the retina where light rays are most sharply focused

some meanings of diff brain structures

pineal gland = pine cone gland cortex = bark (b/c it is the outer covering like the bark is the outer covering of a tree) hippocampus = seahorse (b/c it looks like a seahorse

Outer ear

pinna and auditory canal

primary somatosensory cortex

postcentral gyrus - part of parietal lobe responsible for touch sensory input - we see the same body plan organization where it is anatomically connected (near each other in the brain) - we also see some areas being overrepresented: the lower portion of our face, hands, and mouth - however, we now see our genatalia!

Simple V1 cortical cells

simple Cells in V1 - have receptive fields which have that antagonistic center surround (same as in the retina) except it is stretched a bit - produced by combining outputs of LGN cells in the thalamus - the shape of the receptive field is elongated (lines intead of the donuts that we saw in the retinal cells - these have all kinds of different receptive fields. One example is looking at a vertical line. BUT every angle of line you can imagine there are going to be receptive fields for that (we are just using vertical as the example) - they respond best to stimuli that are shaped like bars/edges that have a particular angle/orientation - we can then graph the response of the simple cortival cell and whenever we see the most action potentials, this can tells us what the receptive field actually is - on-center simple cortical cell: we get the most response/action potential when we have light that is vertical just in the center. We see the fewest when the light is in the inhibitory surround

light as a wave

sinusoidal wave wavelength: the distance between peaks which tells us which color of light/shades of gray we are looking at amplitude: the height of the wave, tells us how bright/intensity of the light

eye muscles

six (6) muscles rotate eye in all directions

Sound results from collisions of molecules

speakers produce alternating bands of high and low air pressure (the boom boom boom) that move through the air like ripples in a pond. When it is compressed, we see a wave that mirrors the activity of the vibration through a wave like pattern. - sound waves travel through the air at a rate of 340 meters per second (fast)

photoreceptor cells of retina

specialized cells filled with light sensitive chemicals called photopigments (they change their shape in presence of light) - the photopigments allow the photorcepetors to resppnd to the external light energy, it starts the transition from external energy into a neural signal humans have a duplex retina: rods/cones RODS: used in a lighting condition called scotopic vision (dim light) CONES: photopic vision (bright light)

parts surrounding/in the spinal cord

still has the meninges coating it (dura, arachnoid, pia) gray matter: center, area with the most cell bodies is in the CENTER (butterfly like) called the "horns" white matter: outside, axon tracts which are up and down (ascending from spinal cord to brain or descending from brain to the spinal cord) are found at the outermost portions of the cord

why do brains have "wrinkles" or convolutions?

the average 20 year old has an average about 100,000 miles of fiber pathways in their brain - if stretched out flat, the cortex would cover an area of about 2.5 sq ft (like a towel) SO - the brain is so wrinkly b/c it is so big! the most efficient way to fit something very very big into a tiny space is to crinkle it up like a piece of paper. so these wrinkles/convolutions increases the surface area which allows us to have the most amount of brain in a small skull. - we want to minimzie the size of the skull for multiple reasons: 1. our neck is not strong enough to support anything much bigger 2. if it was bigger, we would have a hard time being born which we see with french bulldogs that has to be born via c-section (their large skulls)

refraction

the bending of a wave/light as it enters a new medium at an angle - it looks like you have two separate straws in a glass b/c at the surface of the water the light is bending in a way to change our perception - important for visual perception b/c light passes through several layers of tissue/liquid which changes the way the light is focused in the eye (can make ideal or impaired imagery and visual acuity) - lots of species have different adaptations to refraction

comparing hippocampus in rat, monkey, and human

the hippocampus is actually one of the brain structures that is the most similar across all mammals - it has basically the same organization plan which means it is one of the most studied parts of the brain in all of neuroscience b/c looking at a rodent's hippocampus is still informative for the structure of a human hippocampus - since it is connected to learning and memory, and a lot of our behavioral tasks naturally tap into it the combo of interspecies comparison and memory functions makes it a popular/import area to research

Lateral inhibition illusions: a variant of the Hermann grid

the image where you are trying to find how many black circles there are but it looks like they are disappearing (total of 12) but you can not see them all at the same time. You can only see the ones you are focusing on in your center field of view - remember the compensatory mechanisms we talked about with the blindspot: how the brain just fills in the pattern - if you are not directly looking at one spot, i can not see any of the ones on the opposite side. This is because your brain just assumes the gray lines are going to continue

The medulla functions (hindbrain)

the junction between the spinal cord and brain (brainstem) - its functions are vital (essential to life) like breathing, heart rate, blood pressure - is important regarding the inputs from organs which is important for homeostasis, fluid/food intake as well as understanding our pattern of emotions - contains the reticular formation

cross sections of spinal cord use what

the myelin stains of the diff sections of spinal nerves show that the spinal cord is not consistent all the way down - the horns (gray matter/butterfly shape) is not consistent in the diff sections of the spinal cord

Phototransduction in the Rod

the photopigment in a rod is opsin which is located on a disk in the outer segment. rhodopsin contains retinal and it's light sensitive component (opsin) is interesting when it is in the dark: the retinal that is bound to the opsin has a bend to it. when it is in the light: photons are absorbed by rhodopsin molecules, the retinal chemical then changes its structure so that it straightens out

Gyri (gyrus)

the raise areas/elevated areas - the peaks gyri = singular gyrus = plural

sensory humunculus differences in sex

the sensory humunculus are different in males than they are in women - it is hard to find a female homunculus - this is one of those times where we see some sexual dimorphism in the brain in the representation of diff sensory areas

The "dark current" of photoreceptors refers to:

the steady depolarization maintained by photoreceptors when no light is present

where division is most of the brain in?

the telencephalon (part of forebrain)

Opponent Process Theory of Color Vision

the theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision. For example, some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green - these are complementary colors. So when we stared at the green in the flag afterimage illusoin we perceived it as its complementary image of reg. When we stared at the yellow, we perceived it as its complementary color of blue. - so, we can have receptive fields that are red on and green off (red in the middle), we can have green on and red off (green in the middle), we can have blue on and yellow off (blue in the middle) but remember that yellow is produced by the combination of green and red. So technically, it is blue on and green/red off.

why is hypothermia a risky procedure

the warming of the temperature is higher risk for cardiovascular events and strokes, etc - so it is not applicable for everyone with spinal cord damage

Structure of Retina

there are cells between the light and the photoreceptors - the light hits the very back of the retina and then it will start activating the photoreceptors - so the processing of visual info starts at the photoreceptors in the far back of the retina - the light is moving in one direction and the visual info is moving in the opposite direction - the photoreceptors (rods and cones) are as far back as possible/ as far away from the light as possible (it travels through thru the other cells first)

animal kingdom eyes

there are diff ways animals have accomplished the goal of having a sensory organ that responds to light and allows them to captural visual info

something to remember about the convolutions of brain

there is a clear, consistent organization between the convolutions

primary motor cortex (PMC)

this is the precentral gyrus - part of the frontal lobe reslonsible for initiation voluntary body movement - it corresponds to diff parts of the brain: we learned this from electrical stimulation experients in that electrodes caused motion to happen in certain parts of body activating muscles - NOT random, if a part of the body is near something else anatomically the brain representation is simple. ex. the ankle is connected to the knee which is connected to the hip so they are found next to each other called: - topographic organization in which the brain has a plan that matches the body plan - body parts do not get equivalent brain space representation: Motor Humunculus (ex. face and hands which have lots of muscles and we need to have precise control over them these get a lot vs the elbow should move in one directionand therefore does not get as much room)