Primary visual cortex

Question 1

Which fibres enter the primary visual cortex?

Answer 1

myelinated fibres of the geniculocalcarine tract (containing fibres from both eyes)

Question 2

Where is the primary visual cortex located?

Answer 2

within the depths of the calcarine sulcus

extends both above and below its margins on the medial surface of the occipital cortex, extending posteriorly as far as the occipital pole and anteriorly as far as parieto-occipital sulcus

Question 3

What are the extensions of the primary visual cortex (area 17)?

Answer 3

• extends above and below its margins on the medial surface of the occipital cortex
• extends posteriorly to occipital pole
• anteriorly to parieto-occipital sulcus

Question 4

What is at the posterior margin of the primary visual cortex (area 17)?

Answer 4

occipital pole

Question 5

What is at the anterior margin of the primary visual cortex (area 17)?

Answer 5

parieto-occipital sulcus

Question 6

What is the name of the area above the primary visual cortex (area 17)?

Answer 6

cuneus gyrus

Question 7

What is the name of the area below the primary visual cortex (area 17)?

Answer 7

lingual gyrus

Question 8

What part of the visual field do fibres from the superior retinal quadrants represent, and which part of the calcarine sulcus do they pass to?

Answer 8

• represent inferior visual field
• pass to upper lip of calcarine sulcus

Question 9

What proportion of fibres in the visual cortex represents the macula?

Answer 9

1/3 of visual cortex

Question 10

Which part of area 17 are the fibres in the visual cortex representing the macula?

Answer 10

posterior portion of area 17

Question 11

What is the white line or stria (of Gennari)?

Answer 11

created by the myelinated fibres of the geniculocalcarine tract entering the posterior portion of area 17

Question 12

How many basic layers are there in the primary visual cortex (area 17)?

Answer 12

6

Question 13

Which layer in the primary visual cortex is represented by the white line or stria (of Gennari)?

Answer 13

layer IV

Question 14

What are 3 differences between the white line or stria of Gennaria which represent layer IV of the cortex vs the rest of the cortex?

Answer 14

1. thinner (1.5mm) than rest of cortex
2. more cellular
3. predominant cell type small stellate cells (not pyramidal cells)

Question 15

What structures in the stellate cells of primary visual cortex layer IV receive input from right and left eyes?

Answer 15

ocular dominance columns

Question 16

How is the geniculocalcarine projection ordered?

Answer 16

• matching points of retinae of both eyes registered side by side in contiguous columns

Question 17

What is the fate of cells in laminae II and III of the primary visual cortex (area 17)?

Answer 17

project to he secondary visual cortex (areas 18 and 19)

Question 18

What is the fate of cells in lamina V of the primary visual cortex?

Answer 18

project to the superior colliculus

Question 19

What is the fate of cells in lamina VI of the primary visual cortex?

Answer 19

major source of ‘feed-forwad’ to the LGN