Visual System

Question 1

Why do we have a blind spot? Why can’t we detect it?

Question 2

List the 5 major types of cells in the retina. How are they organized in the retina? What is the direction of light?

Answer 2

1. Photoreceptive cells (rods, cones)
2. Bipolar cells
3. Retinal ganglion cells (output)
4. Horizontal cells (processing from bipolar -> RGC)
5. Amacrine cells (p

Question 3

What is the difference between the fovea and the rest of the retina?

Question 4

Why is visual acuity best when images fall on the retina?

Question 5

What are the main differences in the function of rods and cones?

Question 6

Why can’t you see color well in the dark?

Question 7

Describe the connections that result in ON-CENTER OFF-SURROUND receptive field of a retinal ganglion cell.

Question 8

Describe the connections that result in OFF-CENTER ON-SURROUND receptive field of a retinal ganglion cell.

Question 9

How are “ON” and “OFF” achieved in “ON” bipolar cells and “OFF” bipolar cells

Question 10

What is lateral inhibition? What is the functional effect of the inhibition of the selectivity of a response to a stimulus?

Question 11

Why is it useful that photoreceptors are depolarized at rest (thus release glutamate tonically)?

Question 12

What is a receptive field? In the perspective of the primary receptor, second/third-order neuron, and higher order neuron.

Question 13

Describe the organization of the LGN

Question 14

Why can’t we call the LGN simply a relay station in the visual pathway?

Question 15

What is the primary input layer for LGN axons entering V1?

Question 16

How is the retinotopic map in V1 achieved?

Question 17

Explain what this means and why it is important:

The map of the visual field is “distorted,” meaning that the fovea is overrepresented in the LGN and visual cortex even though it only occupys only a small part of the retina.

Question 18

Why are cells in layer IV of V1 monocular?

Question 19

Cells in other layers (not IV) of V1 are binocular

Why is retinotopy preserved in binocular cells of V1?

Question 20

How is the receptive field of a simple cell formed from the receptive fields of LGN cells?

Question 21

How does the receptive field of a simple cell differ from a complex cell?

Question 22

What is an:

Ocular dominance column?

First, define ocular dominance.

Question 23

Determine the effects of lesion in:

• Optic nerve
• Optic chiasm (midline)
• Optic tract
• Thalamocortical tract

How a lesion would affect an individual’s visual field.

Question 24

How do receptive fields differ between:

Parietal lobe (dorsal stream) vs temporal lobe (ventral stream)

Question 25

# Explain the concept of the following: * Chemoaffinity * Gradient effect * Monocluar deprivation * Critical period

Question 26

# Understand the following How the wiriting of visual neural circuits are affected by nature vs nurture