Perception

Question 1

Describe serial processing?

Answer 1

it’s when you have the 1st order neuorn activating the 2nd, which activate sthe 3rd, etc.

it’s basically the basis of the labelled line mechanism for transmitting information

Question 2

Describe parallel processing?

Answer 2

It’s where the signal diverges and you get input from one primary neuron onto multiple secondary neurons

thus, the signal travels thorugh multiple strings of neurons instead of just one as in series processing

Question 4

What is convergence?

Answer 4

it’s where input form 2 cells synapses on one post-synaptic cell

note this can occur across modalities

Question 5

What are the facotors affecting an individua’s awareness of a sensory input?

Answer 5

1. the set of receptors they have
2. the functionality of the receptors they have
3. the receptor mechanism itself
4. selective attention
5. emotions and experiences
6. drugs

Question 6

Through what mechanism are ganglion cells able to detect contract?

Answer 6

through lateral inhibition

Question 7

what cells provide the lateral inhibition for the ganglion cells?

Answer 7

the amacrine cells

Question 8

How do the receptive fields of photoreceptors differ from the receptive fields of the gannglion cells?

Answer 8

photoreceptors just have round recetive fields

ganglion cells have bigger receptive fields and they have a surround and a center (like a doughnut)

Question 9

How will “on” GCs differ from “off” GCs?

Answer 9

on GCs will depolarize in response to bright light (of their preferred color) hitting their center and will hyperpolarize in response to light hitting their surround

OFF GCs will depolarize in response to light hitting their surround and will hyperpolarize in response to light hitting their center

Question 10

What will the bipolar cells do to the signal for an ON gangion cell? How about for an OFF ganglion cell?

Answer 10

remember that photoreceptors hyperpolarize

so…for an ON ganglion cell, the bipolar cell will flip the signal to cause depolarizaiton in the center

for an OFF ganglion cell, the bipolar cell will just send the hyperpolarizaiton as it, causing hyperpolarization in the center

Question 11

How can an amacrine lead to depolarization in the surround of an OFF ganglion cell?

Answer 11

it’s thoruhg lateral inhibition

when activated, the amacrine cells will inhibit the inhibition of hyperpolarization in the surround, causing a depolarization

Question 12

In the visual cortex you basically get a reconstruction of the visual image. What are the 3 dimensions of this?

Answer 12

1. first dimension of organization is where you select fFEATURES of the visual field
   - occurs with alternating eye representation lending itself to ocular dominance
2. in the second dimension you have orientaiton columns, which give you line orientation AND motion
3. Int he third dimensions you have the blob reigons that give you color

Question 13

What dimension of the visual cortex organization gives you depth perception?

Answer 13

the ocular dominance columnar organization

Question 14

How do the ganglion cell responses ultimately lead to motion perception?

Answer 14

1. ganglion cells converge into simple cell responses, which respond to only a specific orientation of a line
2. the simple cell responses combine into complex cell responses, which respond to motion of the line via each simple cell responding to a specific orientation of a line

Question 15

Within the primary visual cortex, what areas are overrepresented?

Answer 15

the fovea is overrepresented relative to the periphery, which makes sense because that’s where the most photoreceptors are

Question 16

what’s the fancy word for depth perception?

Answer 16

stereopsis

Question 17

Since the fovea is overrepresented, is has ____ convergence/

Answer 17

less

Question 18

What is strabismus?

Answer 18

It’s an EOM muscle imbalance that results in a misalignment of the axis of the two eyes

Question 19

What will strabismus result in if it occurs before 6 onths of age? After 6 months of age?

Answer 19

before 6 months of age, the cortex basically suppresses the image of the weaker eye, causing a permanent decrease in visual acuity (amblyopia)

after 6 months, the cortex can’t suppress it, so you get a diplopia because the image falls on different parts of the two retinas

Question 20

In terms of wavelength, what color is short and which is long?

Answer 20

blue has short wabelenths, green is medium, red is long wavelengths

Question 21

In color perception, what gives you luminescence?

Answer 21

activity of both long and medium wavelengths - red and green cones plus rods

Question 22

In color perception, what radoi gives you red/green contrast?

Answer 22

the ratio between long and medium wavelengtsh

Question 23

In color perception, what gives you blue/yellow differences?

Answer 23

short wavelength - (long and medium wavelength)

Question 24

Do we all see color the same?

Answer 24

probably not - everyone has unique distributions of photorecepors on the retina

what we know as perception of color is actually a learned process involving figuring out what “red” is based on our own photoreceptor conglomerate

Question 25

Visual cortex output gets segregated into what two pathways?

Answer 25

ventral stream - to the inferior temporal cortex - the “what” stream

dorsal stream - to the posterior parietal - the “where” stream

Question 26

In terms of vision, what info does the ventral stream provide?

Answer 26

color perception

form - object identification

Question 27

For vision, what info is provided by the dorsal stream?

Answer 27

motion and depth perception

Question 28

What will a lesion in the ventral stream cause? dorsal stream?

Answer 28

ventral = achromatopsia and agnosia

dorsal stream = ideomotor apraxia - can’t execute movements that depend on sight