selective rearing visual cortex and beyond
TRANSCRIPT
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Visual cortex and beyond
Chapter 4
Selective rearing
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Retina
Subcortical Structures
White Matter
Optic Nerve - Optic Chiasm
Cortex
Where do retinal signals go?
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Primary visual area (V1)
Medial view
Lateral view
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MRI / fMRI
MRI - structural or anatomical images fMRI - functional images (measure neural activity)
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Visual cortex activation
A
B
C
C
A
B
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Retinotopic mapping
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Retinotopic organization
• Adjacent locations in space are coded by adjacent sets of neurons (continuity)
Center of gaze
Periphery
RH
Stimulus
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Cortical maps are distorted
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Cortical maps are distorted
Visual stimulus Cortical activation
Center of gaze
Periphery
Visual system organization
• Retinotopic maps in LGN & visual cortex
• Cortical maps are distorted (cortical magnification factor)
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Visual system organization
• Retinotopic maps in LGN & visual cortex
• Cortical maps are distorted (cortical magnification factor)
• Columnar organization – Location columns – Orientation columns – Ocular dominance columns
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Hypercolumns
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Lesioning or ablation experiments
Used by Ungerleider & Mishkin to show ‘What & Where pathways’
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Where / How
What
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What & how pathways - neuropsychological evidence
• Behavior of patient D.F. (CO poisoning)
• Other patients show opposite effects
• Double dissociation
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Patient DF Control Ss
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Visual system organization
• Retinotopic maps in LGN & visual cortex
• Cortical maps are distorted (cortical magnification factor)
• Columnar organization – Location columns – Orientation columns – Ocular dominance columns
• Processing streams
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Modularity
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Visual system organization
• Retinotopic maps in LGN & visual cortex • Cortical maps are distorted
(cortical magnification factor)
• Columnar organization – Location columns – Orientation columns – Ocular dominance columns
• Processing streams • Modularity
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