Visual Pathways

Question 1

Cornea

Answer 1

Clear protective outer layer.

Question 2

Iris

Answer 2

Thin circular structure that controls diameter of the pupil; defines eye color.

Question 3

Pupil

Answer 3

Hole in the center of the iris that allows light to enter.

Question 4

Lens

Answer 4

As light passes through the cornea, the lens refraction occurs to form the image on the retina.

Question 5

Vitreous body

Answer 5

Clear, gel-like structure between the lens and retina.

Question 6

Retina

Answer 6

Layer of cells lining the back wall inside the eye; it senses light and sends signals to the brain so you can see.

Question 7

Fovea

Answer 7

Region of the retina with the highest visual acuity.

Question 8

Macula

Answer 8

An oval region that surrounds the fovea; relatively high visual acuity.

Question 9

Optic disc

Answer 9

Region where the axons leaving the retina gather to form the optic nerve; no photoreceptors.

Question 10

Optical properties of the lens _____ and _____ the projection of the visual image on the retina.

Answer 10

Invert and reverse

Question 11

Two classes of photoreceptors in retina:

Answer 11

Rods and cones

Question 12

Rods

Answer 12

More numerous than cones; main function is for vision in LOW lighting conditions. They do NOT detect color, andy have relatively poor spatial and temporal resolution.

Question 13

Cones

Answer 13

Less numerous; highly represented in the fovea (visual acuity); detects colors, and has relatively high spatial and temporal resolution.

Question 14

Layers of the retina (outermost to innermost)

Answer 14

Photoreceptor layer, outer nuclear layer, outer plexiform layer, inner nuclear layer, inner plexiform layer, then ganglion cell layer.

Question 15

Photoreceptors synapse on _______ cells.

Answer 15

Bipolar

Question 16

Bipolar cells synapse on ___________ cells.

Answer 16

Ganglion

Question 17

Axons of the ganglion cells sent into ________ _______.

Answer 17

Optic nerve

Question 18

True or False: photoreceptors and bipolar cells fire action potential.

Answer 18

False

Question 19

True or False: ganglion cells do not fire action potentials.

Answer 19

False

Question 20

What are the two types of interneurons in the layers of the retina? What do they each modulate?

Answer 20

Horizontal and amacrine cells; horizontal cells modulate photoreceptor and bipolar cell synapses, and amacrine cells modulate bipolar cell and ganglion cell synapses.

Question 21

What are the two classes of center-surround bipolar and ganglion cells?

Answer 21

On-center cells and off-center cells

Question 22

What are the two types of retinal ganglion cells?

Answer 22

Parasol and midget cells

Question 23

Describe parasol cells.

Answer 23

Large cell bodies, large receptive (dendritic) fields, respond best to gross stimulus features and movements, large diameter fibers, and project to magnocellular layer of the lateral geniculate nucleus of the thalamus.

Question 24

Describe midget cells.

Answer 24

Small cell bodies, small receptive (dendritic) fields, more numerous, sensitive to fine visual details and to colors, smaller-diameter fibers, and project to parvocellular layers of the lateral geniculate nucleus of the thalamus.

Question 25

Describe midget cells.

Answer 25

Small cell bodies, small receptive (dendritic) fields, more numerous, sensitive to fine visual details and to colors, smaller-diameter fibers, and project to parvocellular layers of the lateral geniculate nucleus of the thalamus.

Question 26

The optic tract wraps around what structure in the brain?

Answer 26

Midbrain

Question 27

Optic tract supplies what two pathways?

Answer 27

Geniculate and extrageniculate pathway

Question 28

Geniculate pathway synapses where?

Answer 28

In lateral geniculate nucleus of the thalamus

Question 29

Extrageniculate pathway synapses where?

Answer 29

Synapses in the superior colliculus and pretectal areas of the midbrain.

Question 30

Function of the geniculate pathway.

Answer 30

Visual discrimination and perception.

Question 31

Function of the extrageniculate pathway.

Answer 31

Direct visual attention and eye movement towards stimuli.