L7 - neural circuits of stimulus localisation Flashcards
4 examples of object localisation in the visual system
1) Orienting reflex (orientation of the head and eyes to focus salient stimulus on the fovea)
2) Smooth pursuit (following motion object)
3) Prediction of motion during prey capture (motion anticipation)
4) Saccadic movement during inspection - look at different parts of the object
what does ablation of the optic tectum / superior colliculus lead to
disappearance of the orientation reflex
how many ms does it take to see something
60ms
3 important areas involved In stimulus localisation and motion processing
retina
dorsal stream in cortex
superior and inferior colliculus
where does the superior colliculus receive input from
ganglion cells, auditory system, somatosensory system
what is the main function of the superior colliculus
integrate information from different sensory modalities and to regulate saccadic movements (turning of eyes and head)
what is a retinotopic map
organisation whereby neighbouring cells in the retina feed information to neighbouring places in their target structure
what is the foveation hypothesis
that interaction between the two overlapping topographic maps initiates the orienting reflex
why is the foveation hypothesis incorrect
as interaction between these maps is indirect
what is preferred direction
direction that evokes the largest response
what is null direction
direction that evokes no response
is there direction selectivity in the retina
yes - allows to look at input in a more controlled way
what is the morphology of selective cells
highly asymmetric
what experiments can be done on selective cells
sharp electrode recording
patch clamping
what inputs to retinal ganglion cells receive
excitatory - from bipolar cells
inhibitory - from amacrine cells
