Transcript ACTIVITY WAVES IN THE DEVELOPING RETINA

Lecture 05 - main goals:
• Describe the different processing stages of the mammalian visual system; what
gets computed? Different forms of representation? Cortical maps?
• Acquire an understanding of cortical plasticity through occular dominance
columns and orientation selectivity
• Acquire an understanding of higher order visual centers: area MT and the
processing of motion; the aperture problem.
•
discuss sensation vs perception; a case study: stimulation of direction
selective neurons in MT
• Learn about face cells and what they can tell us about the brain
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Eye
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Visual fields
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LGN – lateral geniculate nucleus
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Electrical recordings
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Retinotopy – 2 DG
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Tootell
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OD columns
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Ocular dominance columns develop
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Plasticity of OD columns
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OD Columns
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Pyramidal cells in the visual cortex act as feature
detectors
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Pyramidal cells in the visual cortex act as feature
detectors
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Receptive fields: concentric cells, simple cells, complex
cells
Concentric cells in retina and LGN
simple cells in V1
Response to orientation
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Response to position
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Line detectors – vector graphics
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Optical imaging of intrinsic signals
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Kittens with goggles
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Kittens with goggles
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Pairing visual stimuli
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Retinal waves
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Higher visual areas
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The aperture problem – component vs pattern motion
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Area MT
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Bill Newsome – Tony Movshon: Neural correlates of
perceptual decision
monkey
Threshold ratio < 1

neuron is better than monkey
Threshold ratio > 1
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monkey is better than neuron
neuron
Newsome et al., Nature, 1989
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Cortical microstimulation influences perceptual
judgements of motion direction
Salzmann et al., Science, 1994
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Bill Newsome: cortical microstimulation
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Face cells in the inferotemporal cortex of a monkey
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Quiroga et al., Nature, 2005
The Jennifer Anniston neuron
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The Jennifer Anniston neuron
Quiroga et al., Nature, 2005
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And others
Quiroga et al., Nature, 2005
For example, in one case, a unit responded only to three
completely different images of the ex-president Bill Clinton.
Another unit (from a different patient) responded only to
images of The Beatles, another one to cartoons from The
Simpson’s television series and another one to pictures of the
basketball player Michael Jordan. This suggested that
neurons might encode an abstract representation of an
individual.
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Face inversion effect
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Face inversion effect
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A map of the 32 known visual areas in monkey neocortex and their interconnections (van Essen)
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papers
J. Sharma, A. Angelucci, and M. Sur. Induction of visual orientation modules in
auditory cortex. Nature 404 (6780):841-847, 2000.
L. von Melchner, S. L. Pallas, and M. Sur. Visual behaviour mediated by retinal
projections directed to the auditory pathway. Nature 404:871-876, 2000.
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