Physio exam 2

Axons of LGN neurons form the optic radiations, which terminate in the ___________ (V1).

AGAIN, WHAT THE EFF

This change in membrane potential in hair cells leads to a rapid influx of_____ at base of the cell (just like when an action potential arrives at an axon terminal), causing vesicles to fuse and release neurotransmitter, which causes PSPs in adjacent neurons.

Ca++ ions

Berthold's Rooster Study

Castrated 6 roosters. Left 2 castrated roosters to develop into capons. Re-implanted a testis in 2 roosters. Transplanted a testis from another bird in 2 roosters.

What are two ways olfactory neurons differ from a typical neuron?

Die and are replaced in adulthood (average lifespan 30-60 days). Have many more and diverse subtypes of receptors

Pathway from hair cells to brain:

• Hair cells ⇨ganglion cells • Ganglion cell axons travel via the vestibulocochlear nerve to the cochlear nuclei, which send signals to the superior olivary nuclei. • The superior olivary nuclei receive bilateral input (input from both ears). This is the first site of binaural (two-ear) processing. What is this important for? • From there, signals are sent to the inferior colliculi (primary auditory centers of the midbrain) to the medial geniculate nuclei of the thalamus. Pathways then extend to auditory cortex.

Hair cells in the basilar membrane convert sound to neural activity. • What causes the sterocilia to bend? • When the hairs bend, what happens? • How are ion channels in the sterocilia opened? • What are tip-links? • When ion channels open, do positive or negative ions rush into the cell? Does this cause a depolarization or hyperpolarization of the cell?

When sound causes basilar membrane to ripple, hair cells move relative to tectorial membrane, causing hairs to bend. When hairs bend, tension on tip links physically pops open ion channels. Each stereocilia contains one or two nonselective ion channels, with fine, thread like fibers (tip links) that connect it to neighboring stereocilia tips. Allows positive K+ and Ca++ ions to rush to cell, depolarizing it.

Light enters the eye through the ______, which ______ the light. The light then passes through the ______, which accommodates, or changes shape, to further refract the light.

cornea, refracts, lens,

Latency Differences

differences between the two ears in the time of arrivals of sounds

Intensity DIfferences

differences in loudness at the two ears

If a person is able to identify an object, but is unable to grasp that object, this person has suffered damage to which stream?

dorsal stream

How is blindsight possible?

dual processing, which sends info simultaneously to different brain areas, which support different tasks. Most of the information that is registered on the retina goes to the visual cortex. But a portion of this information bypasses the visual cortex and goes to other parts of the cortex as well - so although not conscious of seeing the object, the person may still perceive the stimulus

Temporal Coding

encodes the frequency of auditory stimuli in the firing rate of auditory neurons

Which part of the ear captures, focuses, and filters sound, which part concentrates sound energies, and which part converts vibrations into neural activity?

external ear, middle ear, inner ear

Each olfactory axon terminates in a specific glomerulus structure in the olfactory bulb of the brain. Each glomerulus receives input from which neurons?

from neurons with the same type of receptors

Sounds activate the primary auditory cortex. What about speech sounds - where in the brain do these sounds activate?

frontal lobe

Which of these neuronal cells - rods, cones, bipolar cells, ganglion cells - fire action potentials?

ganglion cells

There is tonotopic organization at each level. This means neurons are arranged in a map based on what?

map of low to high frequency

Are we able to use olfactory cues to pick up information about other humans (such as genetic compatibility, or ovulation stage)? • Are we more attracted to someone with a similar MHC complex, or an MHC complex different than our own?

maybe. different MHC.

Is our perception of hue based only on the wavelength of light? If not, what feature does our brain compensate for?

no, our brain compensates for shading

(Prosopagnosia) If you showed them a picture of their spouse, could they recognize their spouse? Would they be able to tell if their spouse was smiling in the picture?

no, yes can see smiling

Is flavor based solely on taste?

no. flavor = taste + smell

Are people missing red cones or green cones truly color blind? Can they see any colors? Why are more males than females colorblind?

no. still able to distinguish certain hues. Genes encoding for M and L photopigments are carried on the X chromosomes—in females a normal copy can compensate for a defective gene.

What is unique about smell's pathway to the brain as compared with other sensory modalities' pathways?

one path goes through thalamus to orbitofrontal cortex - perception and discrimination of odors

(two diff explanations of color perception in nineteenth century) The second, the ____________________ theory, hypothesized that the perception of color was based on the values of three opposed pairs of colors: ______/_________, ________/________, _______/________.

opponent-process theory. red/green, blue/yellow, white/black.

(Gestalt psychology) This school of thought emphasizes that humans have a basic tendency to do what?

organize what they see & see patterns rather than random arrangements

Frequency is a physical property of a sound, but our perception of frequency is called _______.

pitch

Place Coding

pitch is determined by the location of the activated hair cells along the basilar membrane

Two signals from the cochlea inform the brain of pitch:

place coding and temporal coding

The cornea and lens refract the light to focus it on what part of the eye?

retina

Visual information from the left visual field is processed in which half of the brain?

right half

The _______ ________ (rods) has high sensitivity to dim light but low acuity due to ________ , while the _____ ______ (cones) detects more detail and has less _______.

scotopic system, convergence, photopic system, convergence

Many mammalian species also have a vomeronasal organ or Jacobson's organ (regressed or absent in great apes and marine mammals). This organ detects pheromones. • Do humans have a vomeronasal organ?

sort of, but it does not contain receptors (so NOPE)

Transduction is the process whereby a receptor cell coverts a stimulus into a neural impulse. Hearing, specifically, is the transduction of _______ into ________.

sound vibrations, neural impulses

Immunocytochemistry (ICC)

techniques use antibodies to determine the location of hormone receptors in the brain.

• Which frequencies are best explained by temporal coding - low or high? Which frequencies are best explained by place coding?

temporal coding = low, place coding = high

Blindsight is:

the ability of people who are cortically blind (damage in their primary visual cortex) to respond to visual stimuli that they cannot consciously see.

What is refraction?

the bending of light rays by a change in the density of a medium, such as the cornea and the lens of the eyes.

Coding of taste: As with other sensory systems, taste uses a labeled line system. What does this mean?

the brain monitors which specific axons are active to determine which tastes are present

How would wearing an eye patch help you if you were, say, a pirate that wanted to navigate through a dark room?

the eye covered by eye patch would be more used to darkness, cover light sensitive eye so you can use originally covered eye to see your surroundings

What is convergence?

the phenomenon of neural connections in which many cells send signals to a single cell

Gestalt psychology proposes..

the whole is greater than the parts.

If you stare at an image of green stripes for an extended period of time, you will see an afterimage of red stripes. Why do you see a red after image? Which theory of color vision does this support, the trichromatic theory or the opponent-process theory?

trichromatic theory?

If an auditory neuron is most responsive to, for example, a frequency of 1,200 Hz, but can respond to frequencies from 500 - 1800, how does the brain know if it's responding to a stimulus with a weak tone at 1,200 Hz, or a stronger one at 500 or 1,800 Hz?

tuning curve?

(two diff explanations of color perception in nineteenth century) Is either of these theories wrong? How do the two theories fit together? (Hint - think stages of processing.)

two stages. retina: red, green, and blue cones. then processed by opponent cells.

Sound waves travel down our ear canal to strike the ________ membrane, causing it to vibrate with the same frequency as the sound. This causes ossicles to tap on the __________ window, converting vibrations from air into movements of fluid in the inner ear.

tympanic membrane, oval

What is range fractionation?

uses different photoreceptors to handle different intensities

If someone was able to see objects but unable to recognize or identify them, this person has suffered damage to which stream?

ventral stream

The cochlea is a coiled, fluid filled organ with three parallel canals (the vestibular canal, the middle canal, and the tympanic canal) • The stapes taps on the oval window on which canal? • The round window is second window that bugles out a little when stapes taps (because canals are filled will non-compressible fluid). Which canal is the round window on? • Which canal contains the organ of Corti?

vestibular canal, tympanic canal, basilar membrane

Our brain processes visual information using two pathways - the '______' and '_____' pathways.

what and where

What kind of information about objects does each pathway specialize in?

what: specialized for identifying and recognizing objects. where: helps the motor system to find objects and move toward them

Could a person with prosopagnosia recognize an object such as a fork?

yes

Each inner hair cell has a maximum sensitivity to a particular frequency. Will it respond to other frequencies?

yes

When the stapes taps on the oval window, it causes ripples in the fluid of the vestibular canal, which in turn causes the basilar membrane to ripple. • Does the entire basil membrane ripple in response to every sound? • How would the basilar membrane respond to a high frequency sound? (Which part would respond - the whole membrane? The area towards the base? Towards the tip?)

yes. different parts respond to different frequencies. High frequency - displaces narrow base of basilar membrane.

What implication does blindsight have for our understanding of consciousness?

Visual information must pass through the visual cortex for us to be conscious of it.

What neurotransmitter do rods and cones release?

WHAT THE EFF

To show a causal link between hormones and behavior, three conditions must be met:

• A hormonally dependent behavior should disappear when the source of the hormone is removed or the actions of the hormone are blocked • After the behavior stops, restoration of the missing hormonal source or its hormone should reinstate the absent behavior • Hormone concentrations and the behavior in question should be covariant - the behavior should be observed only when hormone concentrations are relatively high and never or rarely when hormone concentrations are low

The visual system responds over a wide range of light intensities. It can do this via three mechanisms:

• Adjusting the size of the pupil • Range fractionation • Photoreceptor adaptation

(Rods or Cones) Which respond to specific wavelengths, and which respond to any visible light?

cones

(Rods or Cones) Which are found concentrated in the fovea (near the center of the retina), and which are found in the periphery?

cones, rods

(Rods or Cones) Which function best in broad daylight, and which are needed for twilight and peripheral vision?

cones, rods

We have about how many different receptors for bitter? Do they each cause a different bitter taste, or do all bitters taste the same?

30 types of receptors. all the same.

If an object looks white, are all wavelengths reflected, or absorbed? What about if the object looks black?

An object's color depends on which wavelengths are reflected; the other colors are absorbed

Why does block B appear lighter to us than block A (checkerboard picture)

Brain compensates for relative luminance: assumes it's in a shadow.

If multiple sensory receptors all stimulate the same neuron, this is an example of ......?

I DON'T KNOW

What is the vestibulo-ocular reflex, and why is it important?

Involves high-speed network w/in brainstem that uses vestibular info about head rotations to move eyes in compensation. Without it, we'd have a hard time seeing anything while walking or running.

Balance is maintained by out vestibular system. This system includes three semicircular canals (three fluid-filled tubes in different planes), connected at their ends to the utricle and saccule, and the ampulla— an enlarged region at the base of the canals, containing hair cells. • How is motion transduced into neural signals in this system? • The canals are oriented in three planes of movement: yaw, pitch, and roll. How does the brain know which plane your head moved in?

Nerve pathways connect to motor systems of brain

(kitten and infant monkey study) What does this reveal about critical periods in visual neural development?

Neurons that are not stimulated become inactive and lose synaptic connections.

How are odors transduced into neural signals?

Odorants are inhaled, dissolve into the mucosal layer, and interact with olfactory receptor proteins on the dendrites (G-coupled receptors).

Perceptual Constancy

Our ability to see objects as appearing the same even under different lighting conditions, at different distances and angles.

In a series of studies, kittens and infant monkeys fitted with goggles that allowed in only diffuse, unpatterned light. The googles were removed after infancy. Like humans born with cataracts, these animals could distinguish color and brightness, but not form. Why did this occur - was it due to damage to retinal cells? Or was there some other reason?

Retinal cells still delivered signals to visual cortex, but without proper stimulation, cortical cells had not developed normal connections (animals remained functionally blind to shape)

How do our three types of cones differ in their sensitivities to wavelengths? (Hint - why are they called 'S,' 'M," and "L" cones?)

Their peak wavelength sensitivities do not correspond to wavelengths we see as the principal hues

(two diff explanations of color perception in nineteenth century) The first of these, the _____________________ hypothesis, proposed that the retina contained different receptors for each of three colors (_______, _______, _______), acting like labeled lines for color information.

Trichromatic theory. red light, green light, blue light

Visual experience is not

a simple reporting of the properties of light - our brain constructs our perceptions.

Humans have 350 subtypes of receptors to detect odors, yet we can recognize some 5,000 odors. How do we do this?

activation of a certain combination of different subtypes

• There are four kinds of neural connections with hair cells (each with a different neurotransmitter): afferent and efferent connections to inner hair cells, and afferent and efferent connections to outer hair cells. • Which one of these four connections provides sound perception to the brain? • Which two of these connections control and fine-tune responsiveness of these cells? • Do outer hair cells detect sound? What is the function of outer hair cells?

afferents, efferents. do not detect sound, but convey info to the brain about the state of the basilar membrane

Where are your taste buds (taste receptors) on your tongue? How are tastes transduced into neural signals? How many tastes can your tongue detect?

all over your tongue. gustatory system extends from the tongue, to brainstem nuclei, to the thalamus, and then to the somatosensory cortex. 5 tastes.

• A 500 Hz sound would cause an auditory neuron to fire 500 action potentials per second. Since a neuron can't fire more than about 1000 action potentials per second, how does the volley principle account for the brain's ability to detect frequencies above 1000 Hz?

an individual neuron can't fire faster than 1000x per second. So, neurons work together, alternating firing - can achieve a combined frequencies above 1000x per second.

Rods and cones release neurotransmitters onto ____________ cells, which then release neurotransmitter onto __________ cells. The axons of these cells in turn form the optic nerve, which then carries signals to the brain.

bipolar neurons, ganglion cells

We perceive the wavelength/frequency of electromagnetic waves as _________.

color (hue)

What is prosopagnosia?

condition in which people cannot recognize individual human faces - but can recognize other objects and non-human faces and characteristics

There are three ways sound may fail to be perceived in the cortex: _____, _______, and _____. What are each of these caused by (i.e. what is the mechanism responsible for this type of deafness)? • Where do they take place - the middle ear, inner ear, the brain? • What are some causes of sensorineural deafness? Of central deafness? • How do cochlear implants work? • If both adult and child were given a cochlear implant, why would there be a difference in hearing between an adult who's been deaf his/her entire life and a young child?

conduction deafness, sensorineural deafness, and central deafness. Conduction deafness = middle-ear infection can cause scar tissue, or bone growth in middle ear bones (cause unknown) can prevent them from moving freely. Sensorineural deafness = some people born with genetic abnormalities, or can be caused by drugs, noise pollution, and loud sounds. Central deafness = damage from stroke, tumors, or traumatic brain injury. Cochlear implants = bypass ossicles and hair cells, directly stimulating auditory nerve fibers of the cochlea. Young children- seems to trigger an awakening in pertinent parts of the brain. Will not enable normal hearing in adults if their brain never learned to process sound during childhood

(Rods or Cones) Which detect fine detail?

cones

The shape of the external ear modifies sound energy, enhancing some frequencies while suppressing others. The human ear, for example, enhances sounds between 2000 - 5000 Hz. • Why is this frequency range biologically relevant to us humans?

has to do with human speech

The reason that the fovea has the most acute vision is ....?

high density of smaller, tightly packed cones

Dolphins hear best at _____ frequencies, while mysticetes (baleen whales) hear best at ____ frequencies. How do their basilar membranes correlate with these frequency differences? (i.e., which ones have wider, less stiff basilar membranes, and which ones have stiffer basilar membranes?)

higher, low.

Does light trigger a hyperpolarization or a depolarization of rods and cones (the photoreceptors)?

hyperpolarization

What does Gestalt psychology propose about our perception of figure-ground relationships?

idk

If you are myopic (nearsighted), where does your eye focus faraway objects?

in front of the retina

Sensations are disassembled into

informational bits in our brain then reassembled into our perceptions.

Hair cells in the cochlea are organized into two groups: a single row of _______ and three rows of _________.

inner hair cells and outer hair cells

Sound is the pressure changes (vibrations) in a medium like air or water. We perceive the _______ of sound as 'loudness,' and the ______ of sound as 'pitch.'

intensity (amplitude), frequency

We perceive the amplitude of these waves as _________.

intensity (brightness)

• Which cue (intensity and latency) works best with high frequency sounds? With low frequency sounds?

intensity = high, latency = low

We rely on two kinds of binaural cues locate a sound source:

intensity differences and latency differences.

Most axons in the optic tract reach cells in the ___________ (LGN), the visual part of the thalamus

lateral geniculate nucleus

Does this light trigger cause rods and cones to release more neurotransmitter, or less neurotransmitter?

less

In vision, _______ is transduced into ________ in photoreceptors in the eye.

light, neural signals

A bipolar cell in the retina of the left eye receives input from three cones that lie in a vertical plane. What type of stimulus will excite this neuron?

light?

The projections from the olfactory bulb make direct connections with the frontal cortex, influencing memory and emotion. This is because they synapse onto which areas of the frontal cortex? (Which areas are involved in emotion and memory?)

limbic system (amygdala & hypothalamus)