Neuroanatomy of Vision: Central Pathways

Question 1

Which cell layers of lateral geniculate nucleus receive visual input from cones? Are these Magnocellular or Parvocellular?

Answer 1

Layers 3-6, Parvocellular

Question 2

Which cell layers of lateral geniculate nucleus process motion and contrast information? Are these Magnocellular or Parvocellular?

Answer 2

Layers 1-2, Magnocellular

Question 3

Which layers of lateral geniculate nucleus receive fibers from the contralateral eye?

Answer 3

1,4,6

Question 4

Which layers of lateral geniculate nucleus receive visual input from the ipsilateral eye?

Answer 4

2,3,5

Question 5

Is the lamina cribrosa found on the nasal or temporal side of the retina?

Answer 5

Nasal

Question 6

Information from which part of the visual field is processed in the lower calcarine bank?

Answer 6

Upper part of the visual field (lower part of the retina)

Question 7

Visual information from the macula is processed in which part of primary visual cortex?

Answer 7

The posterior pole

Question 8

Right nasal hemianopsia would result from what type of lesion?

Answer 8

Lesion of the ipsilateral fibers of the right eye at the optic chiasm.

Question 9

Left Homonymous hemianopsia would result from which type of lesion?

Answer 9

Lesion of the right optic tract

Question 10

Bitemporal hemianopsia would result from which type of lesion?

Answer 10

Sagittal lesion of the optic chiasm

Question 11

Blindness in the right eye would result from which type of lesion?

Answer 11

Lesion of the right optic nerve

Question 12

Left Homonymous hemianopsia would result from which type of lesion?

Answer 12

lesion of the right optic tract

Question 13

Left Upper quadrant hemianopsia would result from which type of lesion?

Answer 13

Lesion of Meyers loop

Question 14

Homonymous hemianopsia with macular sparing would result from which type of lesion?

Answer 14

Lesion in striate cortex

Question 15

Define a simple cell in vision processing and how this behavior is achieved:

Answer 15

A cell that responds to a static bar of light. This is achieved by multiple convergent inputs from LGN that represent co-linear parts of a visual field.

Question 16

Define complex cells in vision processing and how this behavior is achieved:

Answer 16

Respond to bars of light that move orthogonal to the preferred orientation of the bar. Behavior is achieved by receiving convergent inputs from simple cells corresponding to colinear parts of the visual field.

Question 17

What are ocular dominance columns? What is contained within each column?

Answer 17

Stripes of neurons in visual cortex that respond preferentially to input from one eye (or both eyes). Orientation microcolumns and color sensitive blobs.

Question 18

What are orientation columns?

Answer 18

micro-columns within ocular dominance columns which represent 180 degrees of the visual field

Question 19

What do cells in orientation micro-columns have in common? in what do they differ?

Answer 19

They all respond to similar orientations from the same point in the field of view. They differ in their receptive properties. Layer IV generally has simple receptive properties while the other layers have complex receptive properties.

Question 20

Give a mechanism for how line and edge detection processing might work:

Answer 20

Similar orientation micro-columns in differing ocular dominance columns could wire together preferentially to combine each field of view and perceive lines and edges.

Question 21

What are the two processing streams of vision and where are they located.

Answer 21

Ventral stream which processes color, form, stereopsis (binocular depth perception), located in the inferotemporal cortex.
Dorsal processing stream processes motion (lesser degree form and stereopsis). Located in the Middle temporal cortex and posterior parietal lobe.