Retinal Mechanisms Flashcards
Photopigment bleaching:
2 molecules combine to form photopigment: retinal and Olson combined molecule is called rhodopsin
What is photopic vision
Suited for high luminance
Low sensitivity/ high acuity
What is mesopic vision
Intermediate luminance and sensitivity/acuity
What is scotopic vision
Low light vision
High sensitivity/low acuity
Mechanisms of adaption to luminance
1.Pupil size
2.switch between rods and cones
3.dark adaptation: bleaching of photopigment
4.field adaptation: automatic gain control with photoreceptor
Rods versus cones:
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
Info processing after the photoreceptor
Retinal processing partially reduces this to things of interest both spatial and temporal
Concept of receptive field
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