wk1: ND - Motion Perception Flashcards
Briefly outline the dorsal motion pathway (3)
V1 –> MT –> extra striate cortex
What does the selectivity of a neuron to direction of movement depend on?
the response latencies of presynaptic neurons
How does directional sensitive neuron summation work?
Some neurons (e.g. neurons A and B) have longer response latencies but are positioned first so the signal reaches them before later neurons (e.g. neurons C and D) which have shorter latencies. As a consequence, when moving from (e.g.) left to right the neurons summate and a response is made, but if it goes the other way the neuronal response does not summate
How does the specific V1 layer affect direction sensitivity?
The proportion of cells that are direction sensitive vary depending on V1 layer
How big are the receptive fields in MT?
Large
Does MT do global motion integration?
yes
Where is the human MST located?
Human MST lies adjacent to MT (known in humans as V5)
How big are the receptive fields in MST?
Large
Why is motion perception important? Name 4 real world uses
Navigation (optic flow)
Hazard avoidance
Peripheral vision is particularly sensitive to motion information
Segmentation of objects
Is there cross-talk between dorsal and ventral streams?
yes
Define Akinetopsia
visual motion blindness
Outline 2 motion pathways in the human visual system (2x3)
M-LGN –> V1 –> MT
Retina –> superior colliculus –> V5
Outline the “Colliculo-cortical pathway” (3)
Retina –> superior colliculus –> V5
What evidence is there to suggest that the colliculo cortical pathway exists as an additional visual motion pathway? (1)
Blindsight: residual sensitivity to stimuli in a blind hemifield (e.g. V1 lesion, but still showing some residual sensitivity to moving stimuli)
