VIsual info pathways

Question 1

what is the anatomical evolution of the optic nerve

Answer 1

optic nerve changes to the optic tract after the optic chiasm

Question 2

what is the pretectum

Answer 2

reflex control of the pupil and lens

Question 3

where does info ascend

Answer 3

in the ventral and dorsal visual pathways

Question 4

what info does the dorsal stream carry

Answer 4

“where” info
- spatial location, mvmt, rotations

Question 5

what info does the ventral stream carry

Answer 5

“what” info
- shapes, faces, objects (object recognition)

Question 6

where does the dorsal stream travel to

Answer 6

parietal lobe

Question 7

where does the ventral stream travel to

Answer 7

temporal lobe

Question 8

what is the relative speed of the two streams

Answer 8

dorsal = faster
ventral = slower

Question 9

do photons travel in a straight line from the source to the pupil

Answer 9

no - they randomly land over a small region due to noise
(point spread function)

Question 10

where is the temporal retina

Answer 10

portion closer to temple (lateral)

Question 11

where is the nasal retina

Answer 11

portion closer to the nose (medial)

Question 12

where does light from the temporal field of vision land

Answer 12

nasal retina

Question 13

where does light from the nasal field of vision land

Answer 13

temporal retina

Question 14

what is the pathway for info from the temporal visual field

Answer 14

info from temporal field of view —> travels to nasal retina —> decussates and travels contralaterally

Question 15

what is the pathway for info from the nasal visual field

Answer 15

info from nasal field of view —> travels to temporal retina —> travels ipsilaterally

Question 16

which pathway is optic flow in

Answer 16

dorsal pathway - helps with mvmt (nothing to do with object recognition)

Question 17

how does the dorsal visual pathway work

Answer 17

complex cells in V1 receive inputs from multiple simple cells which makes them sensitive to moving edges across the visual field

Question 18

where does the direction sensitivity of complex cells in the dorsal pathway come from

Answer 18

pattern / timing of their synaptic input from multiple simple cells

Question 19

when will EPSPs sum to reach threshold in the dorsal pathway

Answer 19

only when the edge is moved in the complex cells preferred direction

Question 20

which neurons are sensitive to the direction of optic flow info within their receptive field

Answer 20

neurons in the medial temporal lobe (area MT)

Question 21

what is pathway for info in the dorsal visual pathway

Answer 21

info travels from V1 (enter at layer 4) —> V2 —> area MT (medial temporal lobe)

Question 22

how does object recognition occur in the ventral pathway

Answer 22

occurs through the convergence of line receptive fields in V1 into shape receptive fields (V2/V4)
(moves up processing levels)

Question 23

what structure allows us to recognise faces

Answer 23

IT - inferior temporal lobe
- certain neurons in temporal lobe that fire very high firing rates for only one face (like place cells for faces)

Question 24

what is the pathway for info in the ventral visual pathway

Answer 24

V1 —> V2 —> V4 —> IT (inferior temporal lobe) —> hippocampus

Question 25

what is the difference between the monocular and binocular portions

Answer 25

monocular = can only see with one eye
binocular = can see with both eyes (overlapping)