selective rearing visual cortex and beyond

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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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4

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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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5

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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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7

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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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