Visual system

Question 1

definition: prosopagnosia

Answer 1

difficulty identifying faces

Question 2

definition: scotoma

Answer 2

visual field defect

Question 3

which receptor mediates scotopic vision?

Answer 3

rods

Question 4

which receptor mediates photopic vision?

Answer 4

cones

Question 5

which retinal cell type can produce an action potential?

Answer 5

ganglion cells

Question 6

which retinal cells are output cells?

Answer 6

ganglion cells

Question 7

which retinal cells capture photons?

Answer 7

ganglion cells

Question 8

what is the function of retinal projections to the suprachiasmatic nuclei?

Answer 8

circadian rhythms

Question 9

what is the function of retinal projections to the pretectal nuclei?

Answer 9

meidates pupillary light reflexes

Question 10

what is the function of retinal projections to the LGN?

Answer 10

relays to visual cortex and receives input from visual cortex (90% of retinal axons terminate here)

Question 11

what is the function of retinal projections to the superior colliculi?

Answer 11

in response to visual (or auditory or somatic) stimuli can cause eyes, head, and even body to turn toward stimuli

Question 12

what is the function of the dorsal visual stream to higher visual areas? ventral stream?

Answer 12

1. dorsal - analysis of motion and relative positions of objects in visual scene - selectivity for direction and speed of movement 2. ventral - high level form vision and object recognition - selectivity for shape, color, and texture

Question 13

what is the clinical significance of having different pathways for different aspects of vision?

Answer 13

restricted cortical lesions result in different types of selective visual deficits - can result in prosopagnosia or object agnosia

Question 14

what is the location of the genes for the cone pigments?

Answer 14

1. red and green - X chromosome 2. blue - chromosome 7 3. rhodopsin - chromosome 3

Question 15

which mechanisms of depth perception are monocular? which require vision in both eyes?

Answer 15

1. monocular - size and motion 2. binocular - stereoscopic

Question 16

deficiency of which vitamin can cause night blindness?

Answer 16

vitamin A

Question 17

the ciliary muscle contracts in response to what type of autonomic innervation?

Answer 17

parasympathetic

Question 18

definition: receptive field of a neuron

Answer 18

area of retina from which the neuron can be influenced

Question 19

what is the result of a lesion to the central part of the optic chiasm?

Answer 19

bitemporal hemianopsia

Question 20

what is the result of a lesion to the optic tract?

Answer 20

homonymous hemianopsia

Question 21

what is the result of a lesion to Meyer’s loop?

Answer 21

superior quadrant anopsia contralateral to lesion