Retinal Mechanisms

Question 1

Photopigment bleaching:

Answer 1

2 molecules combine to form photopigment: retinal and Olson combined molecule is called rhodopsin

Question 2

What is photopic vision

Answer 2

Suited for high luminance

Low sensitivity/ high acuity

Question 3

What is mesopic vision

Answer 3

Intermediate luminance and sensitivity/acuity

Question 4

What is scotopic vision

Answer 4

Low light vision

High sensitivity/low acuity

Question 5

Mechanisms of adaption to luminance

Answer 5

1.Pupil size
2.switch between rods and cones
3.dark adaptation: bleaching of photopigment
4.field adaptation: automatic gain control with photoreceptor

Question 6

Rods versus cones:

Answer 6

1.Rod cells are more sensitive that cones, by 1 order of magnitude
2.a much bigger difference comes from convergence of rods onto ganglion cells

Question 7

Info processing after the photoreceptor

Answer 7

Retinal processing partially reduces this to things of interest both spatial and temporal

Question 8

Concept of receptive field

Answer 8

1.ganglion cell is the final output of the retina
2. Each ganglion cell may respond to many photoreceptors
3.shine a light on the retina to determine the ganglion receptive field