Chapter 3 - The Eye and the Retina

Question 1

1- Explain ganglion cell receptive fields.

Answer 1

Hartline:
* Pioneering research
* Nobel Prize in Physiology and Medicine in 1967
* Discovery of a property of neurons called the neuron’s
receptive field.

• Hartline isolated a single ganglion cell axon in the
  opened eyecup of a frog.
• Illuminated different areas of the retina and
  found that the cell he was recording from responded only when a small area of the retina was illuminated.
• He called the area the receptive field of that RGC
• Receptive field covered a much greater area than
  a single photoreceptor.
• Receptive fields overlap, so stimulating at a particular point on the retina will generally activate a number of fibers in the optic nerve.
• Each ganglion cell monitors a small area of retina.
• Because there are many
  ganglion cells, just as there are many spectators.
• All of them together take in
  information about what is
  happening over the entire
  retina.
• Stephen Kuffler (1953) measured ganglion cell receptive fields in the cat and reported a property of these receptive fields that Hartline had not observed in the frog.
• Ganglion cells have center-surround receptive fields that are arranged like concentric circles in a center-surround
  organization.

Question 2

2- Explain center-surround organization (on-center ganglion cells, off-center ganglion cells)

Question 3

3- Explain lateral inhibition.

Question 4

4- Explain the Hermann Grid.

Question 5

5- Explain center-surround receptive fields and edge enhancement. Explain Mach bands.

Answer 5

(more explanations looking at images and graphs)

An illusion resulting from overlap of superimposed normal structures.