Exam 4 -- Visual Cortex

Question 1

The koniocellular layers in the LGN synapse with which layers of V1?

Answer 1

Layers 2 and 3

Question 2

The parvocellular layers in the LGN synapse with which layer of V1?

Answer 2

4C-beta (also 4A)

Question 3

The magnocellular layers in the LGN synapse with which layer of V1?

Answer 3

4C-alpha

Question 4

Which cells in the visual cortex have axons that usually do not leave the cortex?

Answer 4

Stellate

Question 5

Which cells in the visual cortex have axons that commonly leave the cortex?

Answer 5

Pyramidal

Question 6

Projections to the extrastriate area originate in particular from which layers of V1?

Answer 6

Layers 2/3

Question 7

In which layer of V1 does figure-ground and binocularity begin?

Answer 7

Layer 2

Question 8

Projections to the lower visual centers (LGN, pulvinar) original in particular from which layer of V1?

Answer 8

Layer 6

Question 9

Which layer of V1 sends fibers to the superior colliculus?

Answer 9

Layer 5

Question 10

What percent of the retinal area is the fovea, and what percent of the striate cortex is devoted to foveal vision?

Answer 10

0.01% of foveal area; 8% of striate cotex.

Question 11

Simple cortical cells respond to what kind of stimulus?

Answer 11

Orientation. They can be on-off, or edge detectors.

Question 12

Complex cortical cells respond to what kind of stimulus?

Answer 12

Unidirectional movement.

Question 13

True or false: hypercomplex cells are real.

Answer 13

False; they are not real. They were proposed by Hubel and Wiesel, but turned out to be incorrect.

Question 14

True or false: simple and complex cortical cells are sensitive to the length of a stimulus (they have end stops).

Answer 14

True.

Question 15

There is a regular shift in orientation sensitivity as you move along the surface of the cortex. A complete circular set of orientation edge detectors is called what?

Answer 15

Hypercolumn

Question 16

Ocular dominance columns respresent neurons that get the majority of their input from _________ (one/both) eye(s).

Answer 16

One.

Question 17

Where are the disparity cells of our visual system located?

Answer 17

V2 for complex cells, V3 for local motion.

Question 18

There are two categories of coarse stereo cells: far and near. Which of these is excited if an object is beyond the point of fixation and inhibited if the object is closer than the point of fixation?

Answer 18

Far coarse cells. Near coarse cells are the opposite (excited to nearer than fixation, inhibited to further than fixation).

Question 19

___________ stereo cells make up 30% of disparity detectors.

Answer 19

Coarse

Question 20

________ stereo cells make up 50% of disparity detectors

Answer 20

Tuned excitatory (fine)

Question 21

________ stereo cells make up 20% of disparity detectors

Answer 21

Tuned inhibitory (fine)

Question 22

Fine stereo cells are sensitive to specific disparities, up to what point?

Answer 22

Up to 1 degree.

Question 23

Moderate and higher uncorrected astigmatism during childhood causes what kind of amblyopia? How would you treat it?

Answer 23

Meridional amblyopia; treat with full-time wear of full correction of all cylinder measured on wet retinoscopy.

Question 24

How much anisometropia is typically required for symptomatic aniseikonia?

Answer 24

2.00 D or more

Question 25

What percent in size difference is needed before aniseikonia causes symptoms? To what percent is the Aniseikonia Inspector Software accurate?

Answer 25

2% size difference needed for symptoms; Aniseikonia Inspector accurate to 0.1%

Question 26

Base out makes the binocular image look _______ (smaller/larger).

Answer 26

Smaller

Question 27

Base in makes the binocular image look _______ (smaller/larger).

Answer 27

Larger