Chap 3 (Senses & Perception)

what is transduction (in relation to senses)

the process of turning stimuli such as light or food molecules into electrical signals

what is the process of turning stimuli such as light or food molecules into electrical signals called

transduction

what percentage of the cerebral cortex is involved in vision

30%

which sense do we know the most about

vision

we primarily gain knowledge about the way light energy is converted into electrical signals through what two animal models

fruit flies (drosophila) and mice

what are the two most important animal models for studying higher level visual processing

monkeys and cats

what is the function of the iris

regulates how much light enters the eye by changing the size of the pupil

what is the function of the lens in your eye

it focuses incoming light on the retina

what structure, other than the lens, focuses light in the eye

the cornea

what structure regulates how much light enters the eye by controlling the size of the pupil

the iris

how does the lens focus light coming from a specific distance

it thickens or flattens

describe the way that an image that is projected on to the retina is oriented

objects on the right of the visual field are detected by the left side of the retina and vice versa, objects on the upper part of the visual field are detected by the lower part and vice versa

where does processing of visual information first begin

at specialized cells in several layers of the retina

what are the three types of neurons that are found in the retina

photoreceptor cells, ganglion cells, and interneurons of various types

what happens between cells in the retina before neurons project to the brain

cells communicate extensively with one another

where are photoreceptors in the retina in relation to other neurons

at the back, behind the ganglion cells and interneurons

what does light have to travel through before it reaches the photoreceptor cells (other than the lens and cornea)

the ganglion cells and interneurons of the retina

the axons of which type of neurons in the retina join together to make the optic nerve

ganglion cells

what percentage of photoreceptors are rods

95%

which type of photoreceptor cell allows you to see in dim light

rods

which type of photoreceptor cell is more sensitive to light

rods

which type of photoreceptor cell picks up fine detail and color

cones

what percentage of photoreceptor cells are cones

5%

there are three different types of cones, each of which is sensitive to a specific color of light. What three colors can they detect

red, green, or blue

how do we see a spectrum of color despite only having three types of cones for three specific colors

the activity of different cones overlap

where are cones most densely packed

in the fovea

what two types of cones (sensitive to what two colors) are in the fovea

cones sensitive to red light and cones sensitive to green light

what is the area immediately around the fovea called

the macula

what part of the retina is important for reading and driving

the macula

what is the leading cause of blindness in individuals over 55 yrs old

macular degeneration

what is macular degeneration

death or degeneration of photoreceptors in the macula

neurons in each of the three layers of the retina typically receive input from what general amount (few, some, many, etc.) of neurons from the preceding layer

many

in which area of the retina do ganglion cells receive input from the fewest cones

the macular area

where in the retina do ganglion cells receive input from several photoreceptor cells

the margins of the retina

why is your peripheral vision less detailed

because the ganglion cells receive input from much more photoreceptor cells than in the fovea, making the vision more general and less detailed

what is the portion of visual space providing input to a single ganglion cell called

the ganglion cell's receptive field

what is a retinal ganglion cell's receptive field

the portion of visual space providing input only to it

how is a retinal ganglion cell excited and inhibited

for a retinal ganglion cell to be excited, light must strike the center photoreceptor in its receptive field. Hitting the receptive field anywhere else will inhibit it, and hitting both the center and other places will cause it to be weakly excited.

what is center-surround antagonism in the retina

it is the concept that a ganglion cell will only be excited if light hits the photoreceptor cell which is at the center of its receptive field.

what is the function of center-surround antagonism

it is the first way our visual systems maximize the perception of contrast.

how is neural activity of retinal ganglion cells transmitted to other brain regions

via the optic nerve

what is the "blind spot"

it is the spot in our visual field where the optic nerve leaves the eye and where we have no photoreceptors

How does the brain fill in the blind spots

it uses information from the other eye

where do optic nerves meet/cross

optic chiasm

what is the optic chiasm

the point where the optic nerves meet/cross

what structures are connected by the optic tracts

the optic chiasm and the lateral geniculate nucleus in the thalamus

what is significant about the middle layer of the primary visual cortex

it has similar receptive fields to the retina and can preserve the retina's visual map.

what is significant about cells above and below the middle layer in the primary visual cortex

they have more complex receptive fields and register stimuli shaped like bars or edges or with particular orientations

how complex and selective do visual receptive fields become

some neurons only respond to particular objects or faces

specific cells can respond to edges at a certain \_________ or edges \_________ in a particular \___________________

angle; moving; direction

where does the dorsal visual stream go

up toward the parietal lobe

where does the ventral visual stream go

down to the temporal lobe

do parallel processing streams interact

yes

the ventral "\______" stream

what

the dorsal "\______" stream

where

what is seeing with two eyes called

binocular vision

why does binocular vision help you perceive depth

the two eyes perceive objects at a slightly different angle

what is strabismus

the condition of having crossed eyes

what binocular cue do people with strabismus miss out on

depth perception

does the origin (left eye, right eye) of visual signals influence which side of the brain they project to

no

signals from the left half of the visual field project to which side of the brain

the right

each half of the cerebrum is responsible for processing information from which side of the body

the opposite side

research with what two animal models has led to better therapies for strabismus

cats and monkeys

why do children with strabismus lose vision in one eye and can this loss of vision be treated

they initially have two functioning eyes, but these eyes don't cooperate to make a 3d image, so they eventually favor one eye and the other degenerates. This can be treated but only at a young age

beyond what age does strabismus induced blindness become permanent

around 8

how is strabismus treated

at a young age (

what are your ears detecting

pressure waves in the air

what is the funtion of the pinnae

they funnel sound into your ear canal

what is the function of the tympanic membrane

It vibrates in response to pressure changes produced by sound waves and sends these vibrations to the middle ear bones

what is another name for the tympanic membrane

the eardrum

what are the three sound-amplifying bones in the middle ear

the malleus (hammer), incus (anvil) and stapes (stirrup)

what is the function of the stapes

it acts like a piston, pushing on the oval window in response to sound

what fills the middle ear area vs the inner ear area

the middle ear is air, the inner ear is fluid

how is the cochlea shaped

like a snail shell

how are pressure waves in the fluid of the cochlea transduced

via hair cells

what is the function of the basilar membrane in the ear

it is tuned along its length to different frequencies of sound and resonates with the fluid in the cochlea at those frequency, moving the hair cells on top of it upward to hit the tectorial membrane

what is the function of the tectorial membrane in your ear

it bends the hair cells

what part of the cochlea resonates most with high pitched sounds

the membrane in the outermost coil, near the oval window

what part of the cochlea resonates most with low pitched sounds

the membrane in the innermost coil

how are hair cells in your ear excited

the hair cells bend against the tectorial membrane, opening small ion channels in the stereocilia that allow ions in the surrounding fluid to rush in, creating an electrochemical signal

what nerve connects the brainstem and the hair cells in the ear

the auditory nerve

what two structures does the auditory nerve connect

the brainstem and the hair cells in your ear

where does sound information go when it reaches the brainstem

to the thalamus and on to the auditory areas of the cerebral cortex

what do the thalamus and brainstem do with auditory information

they compute the direction and location of a sound

describe the way in which sound information is carried to and throughout the primary auditory cortex

the frequency map of the basilar membrane is maintained (tonotopic organization)

describe the ways that higher cortical neurons can respond to sound

they can respond to sound qualities such as intensity, duration, or change in frequency; complex sounds; combinations of tones; harmony; rhythm; and melody

although both sides of the cortex process auditory information, the left side is particularly responsible for processing/understanding what

speech

what might be the result of damage to wernicke's area

the patient can hear speech but cannot understand what is being said

can hair cells in your inner ear regrow

no

what is gustation

sense of taste

what is olfaction

sense of smell

what are your tongue and your nose detecting

specific molecules in the air or in your food

why are taste and smell important for survival

they detect substances which might be dangerous to inhale or ingest

can taste receptors regenerate

yes

can smell receptors regrow

yes

what are gustatory cells

taste receptors

where in the mouth do taste buds form

on the tongue and at the roof and back of the mouth

how many taste buds does the average person have

5,000 - 10,000

at what age do we begin to lose taste buds

50

how many sensory cells are in a single taste bud

50-100