Vision continued

Question 1

2 relevant properties of light

Answer 1

wavelength-important for perception of color

intensity-important for perception of brightness

Question 2

3 types of movements

Answer 2

vergence- cooperative movements that keep the image of the target object on corresponding parts of the 2 retinas
saccadic-gaze shifts abruptly; unconscious to us
pursuit- movement that the eyes make to maintain an image of a moving object on the fovea

Question 3

If level of illumination is high…

Answer 3

sensitivity is not important
pupils constrict
provides sharper image
greater depth of focus

Question 4

if illumination is low…

Answer 4

receptors aren’t activated successfully
pupils dilate to let in more light
worse acuity and depth of focus

Question 5

How does vision reach the brain?

Answer 5

Hyperpolarization of photoreceptor-> depolarization of bipolar cells-> excitation of ganglion cell -> ganglion cell axons bring info to rest of brain -> ascend through optic nerve -> terminate in LGN of thalamus

Question 6

If a neuron receives info from photoreceptors located in:

Answer 6

fovea
then the receptive field = fixation point
periphery of retina
then the receptive field= off to one side

Question 7

rebound effect

Answer 7

neurons that are inhibited when light is on have burst of excitement when light goes off and vice versa

Question 8

genetic defects in color vision

Answer 8

Protanopia/Deuteranopia- red and green hues are confused/ cones filled with opposite color
Tritanopia- can’t see blue hues- all red and green/rare

Question 9

striate cortex

Answer 9

AKA primary visual cortex, V1
has 6 layers
25% of striate cortex analyzes foveal info
neurons w/in the blob are sensitive to color and low spatial frequencies
Each module records info from 1 part of visual field- perception and completion of visual scene DOES NOT occur in striate cortex. Info is analyzed in visual association cortex

Question 10

Neurons in V1 respond to….

Answer 10

orientation
movement
spatial frequency
retinal disparity
color 
... of a visual stimulus