Lecture 14: Vision 3

Question 1

Compare foveal and extrafoveal vision

Answer 1

Fovea has 1:1 ratio of PR:GC, extrafovea has 15-45:1. Therefore there is high acuity at the fovea, low sensitivity. opposite is true for extrafovea

Question 2

Describe how visual info goes from the retina to the visual cortex

Answer 2

Only the nasal retina stuff cross over. Will cross over at the optic chiasm. All info goes to lateral geniculate nucleus, from there to the visual cortex at the occipital lobe (layer 4)
Nasal images go contralateral, temporal images go ipsilateral

Question 3

Describe the striatecortex receptive fields

Answer 3

V1 cells respond best to bar of light in particular orientation. This is due to how the receptive fields of the photoreceptors combine, then how the LGN receptive fields combine further
organized in orientation columns

Question 4

Describe the complex cell receptive fields

Answer 4

have directional specificity, also orientation specificity

Question 5

How is colour distinguished

Answer 5

Different frequency activation of cones
spectral opposition. some are activated by yellow/inhibited by red, activated by green/inhibited by blue
Double opponency - work best via contrast, 2 bands of the same colour will cancel out firing