Vision Part 2 (Slides 10-18, Exam 1)

Question 1

Ganglion cells send their axons into the CNS. Axons cross at the ________________. Each optic tract looks at the contralateral visual field. The nasal half of each retina crosses. The axons of ganglion cells have no myelin, but as they pass through the sclera they acquire myelin and form the ______________

Answer 1

optic chiasm, optic n. (CN II)

Question 2

Anterior to the infundibular stalk, the 2 optic nerves cross at the optic chiasm, these axons then form the….

Answer 2

optic tract

Question 3

The optic tract curves around the cerebral peduncle and terminates in the thalamus at the….

Answer 3

lateral geniculate nucleus (LGN, in this 6 layered nucleus, the fibers terminate in a precise retinotopic pattern, any given point in the visual field is represented in all 6 layers, but each layer has inputs from 1 eye)

Question 4

Layer 1,4, and 6 of the LGN receives input from who?

Answer 4

contralateral (nasal 1/2) eye

Question 5

Layer 2, 3, and 5 of the LGN receives input from who?

Answer 5

ipsilateral eye

Question 6

Which layers of the LGN receive info from ganglion cells sensitive to color and form? This is the parvocellular layer/system

Answer 6

layers 3-6 (P for processing color)

Question 7

Which layers of the LGN receive info from ganglion cells with info on movement and contrast? This is the magnocellular layer/system

Answer 7

layers 1 and 2 (M for movement and contrasts (contrast means edges- where one object stops, another one starts)

Question 8

The projections from the LGN to the cortex form the ___________________ within the internal capsule (white matter). A retinotopic organization is maintained here

Answer 8

optic radiation

Question 9

Which lobe is the primary visual cortex in?

Answer 9

occipital lobe

Question 10

The __________________ neurons (layers 3-6 of the LGN) are the dominant class which are sensitive to color and are more capable of discriminating fine details and form from the other LGN layer neurons

Answer 10

parvocellular

Question 11

The ____________________ neurons (layers 1 and 2 of the LGN) are from large ganglion cells sensitive to movement and contrast

Answer 11

magnocellular

Question 12

The visual pathway ends retinotopically in the cortex, area ______ or the occipital lobe is the primary visual cortex

Answer 12

17

Question 13

Inferior visual fields project above the ________________ sulcus (medial occipital lobe)

Answer 13

calcarine

(superior visual fields are below the sulcus, central visual fields like macula and fovea re more posteriorly, peripheral vision more anteriorly)

Question 14

Many visual fibers terminate in 1 layer and it appears as a white band or stripe in the visual cortex. What is this called?

Answer 14

striate cortex

Question 15

What are the visual association areas also known as?

Answer 15

area 18 and 19 (area 17/primary visual cortex info goes here)

Question 16

What is A?

Answer 16

retina

Question 17

What is B?

Answer 17

optic n.

Question 18

What is C?

Answer 18

optic chiasm

Question 19

What is D?

Answer 19

optic tract

Question 20

What is E?

Answer 20

lateral geniculate nucleus (LGN) of the thalamus

Question 21

What is F?

Answer 21

optic radiation

Question 22

What is G?

Answer 22

visual cortex

Question 23

A number of fibers within each optic tract bypass the LGN and form a bundle for the superior colliculus. The visual cortex (area 17) also projects to the superior colliculus. This plays a role in….

Answer 23

visual reflexes (turning head to visual stimuli)