lecture 32: vision (CNS processing & cortical representation)

what are some of the key functional anatomical structures involved in the visual pathway?

* optic nerve
* optic tract
* optic chiasm
* LGN
* visual cortexes (V1-V5)

what is the optic radiation ?

large white matter tract which joins the thalamus to the primary visual cortex (V1)

where do fibres cross over in the visual pathway?

optic chiasm

when does the optic nerve become the optic tract?

after the optic chiasm

describe the nomenclature of the visual fields

* superior
* inferior
* temporal
* nasal

what is the pathway of information from the retina → V1?

1. retina
2. optic nerve
3. optic chiasm (where fibres cross over)
4. LGN
5. striate cortex (V1)

T/F: in the LGN, info the from the L & R eyes is kept segregated in diff layers

true

how many layers does the LGN have?

6

which layers does ipsilateral info go through from the LGN?

2, 3, 5

which layers does contralateral info go through from the LGN?

1, 4, 6

what types of cellular layers does the LGN have in it?

1. magnocellular
2. parvocellular
3. koniocellular

respectively, what do the M, P, & K layers channel info on?

M = motion

P = fine res & colour

K = we don’t really know, but perhaps involved in blue/yellow light, motion, & eye movements

which is the dominant flow of direction in the LGN?

backwards

T/F: there is ONLY serial flow of info to brain, no parallel inputs enter V1

false, from LGN onwards, there are parallel inputs into V1

T/F: channels combine once entering brain as fibres mix from park, magno, and konio cellular inputs

true

T/F: in V1, L & R eye info is STILL kept segregated. diff neighbouring chunks of V1 layers only recieve info L OR R eye

true

what is functional specialisation?

what the area does best, not that it does only that

describe functional specialisation in visual maps

V1-V5; each region is specialised for a diff aspect of vision

e.g. V4 = specialised for colour

V5 = specialised for motion

FFA = feasible face area = specialised for facial recognition

what streams of information exist for specialised info, and what info do they convey?

**ventral** = specialised info going down temporal lobe; linked to what an object in the REAL WORLD might be

**dorsal** = specialised info going parietal lobe; linked to info on WHERE objects are

T/F: there are complex connections in feed fwd, feed back, and parallel pathways as well as short circuits and routes

true