VIsual info pathways Flashcards
what is the anatomical evolution of the optic nerve
optic nerve changes to the optic tract after the optic chiasm
what is the pretectum
reflex control of the pupil and lens
where does info ascend
in the ventral and dorsal visual pathways
what info does the dorsal stream carry
“where” info
- spatial location, mvmt, rotations
what info does the ventral stream carry
“what” info
- shapes, faces, objects (object recognition)
where does the dorsal stream travel to
parietal lobe
where does the ventral stream travel to
temporal lobe
what is the relative speed of the two streams
dorsal = faster
ventral = slower
do photons travel in a straight line from the source to the pupil
no - they randomly land over a small region due to noise
(point spread function)
where is the temporal retina
portion closer to temple (lateral)
where is the nasal retina
portion closer to the nose (medial)
where does light from the temporal field of vision land
nasal retina
where does light from the nasal field of vision land
temporal retina
what is the pathway for info from the temporal visual field
info from temporal field of view —> travels to nasal retina —> decussates and travels contralaterally
what is the pathway for info from the nasal visual field
info from nasal field of view —> travels to temporal retina —> travels ipsilaterally
which pathway is optic flow in
dorsal pathway - helps with mvmt (nothing to do with object recognition)
how does the dorsal visual pathway work
complex cells in V1 receive inputs from multiple simple cells which makes them sensitive to moving edges across the visual field
where does the direction sensitivity of complex cells in the dorsal pathway come from
pattern / timing of their synaptic input from multiple simple cells
when will EPSPs sum to reach threshold in the dorsal pathway
only when the edge is moved in the complex cells preferred direction
which neurons are sensitive to the direction of optic flow info within their receptive field
neurons in the medial temporal lobe (area MT)
what is pathway for info in the dorsal visual pathway
info travels from V1 (enter at layer 4) —> V2 —> area MT (medial temporal lobe)
how does object recognition occur in the ventral pathway
occurs through the convergence of line receptive fields in V1 into shape receptive fields (V2/V4)
(moves up processing levels)
what structure allows us to recognise faces
IT - inferior temporal lobe
- certain neurons in temporal lobe that fire very high firing rates for only one face (like place cells for faces)
what is the pathway for info in the ventral visual pathway
V1 —> V2 —> V4 —> IT (inferior temporal lobe) —> hippocampus
