Visual System

Question 1

Rods

Answer 1

Sensitive to low intensity light; most numerous

Question 2

Cones

Answer 2

Sensitive to higher levels of light; found in the fovea; provide for greatest acuity and color vision

Question 3

Photoreceptor layer

Answer 3

When light strikes, breaks down molecules of photopigment; briefly hyperpolarizes the membrane of photoreceptor (releasing less neurotransmitter)

Question 4

Bipolar layer

Answer 4

Decrease in neurotransmitter depolarizes the membrane of the bipolar cell (causing it to release more neurotransmitter)

Question 5

Ganglion layer

Answer 5

Release of neurotransmitter excites ganglion cells that send excitatory messages to the brain, increasing its firing rate

Question 6

Optic chiasm

Answer 6

A cross-shaped connection between the optic nerves, located below the base of the brain, just anterior to the pituitary gland

Question 7

Dorsal lateral geniculate nucleus (LGN)

Answer 7

A group of cell bodies within the lateral geniculate body of the thalamus; receives inputs from the retina and projects to the primary visual cortex

Question 8

Dorsal stream of vision

Answer 8

Extends to the posterior parietal cortex; involved in perception of spatial location (where it is; movement)

Question 9

Ventral stream of vision

Answer 9

Extends to the inferior temporal cortex; involved in perception of form (what it is; color)

Question 10

Magnocellular layers (LGN)

Answer 10

Sensitive to movement, depth perception, not to color

Question 11

Parvocelluar layers (LGN)

Answer 11

Associated with receiving information from red and green cones

Question 12

Koniocellular sublayers (LGN)

Answer 12

Associated with receiving information from blue cones

Question 13

Simple cells

Answer 13

Excite at one point in the receptive field but inhibit when the stimulus changes orientation

Question 14

Complex cells

Answer 14

Excite at one point but continue to respond when the stimulus changes orientation

Question 15

Cerebral achromatopsia

Answer 15

Vision without color; inability to discriminate hues leading to loss of color vision; caused by damage to V8 area of visual associated cortex

Question 16

Visual agnosia

Answer 16

An inability to perceive or identify a stimulus by means of particular sensory modality

Question 17

Apperceptive

Answer 17

Failure to perceive objects although visual acuity is normal; failure in high-level perception

Question 18

Associative

Answer 18

Inability to verbally identify objects that are perceived visually even though they may be drawn or matched

Question 19

Prosopagnosia

Answer 19

Inability to recognize faces

Question 20

Akinetopsia

Answer 20

Inability to perceive movement

Question 21

Retina

Answer 21

Interior lining of neural tissue on the back of the eye containing photoreceptors