Lecture 2: Vision and Visual Pathways

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Lecture 2 Vision and Visual Pathways
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Eye Cornea Pupil Lens retina Photoreceptors fov
ea (macula) optic disk
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AMD
RP
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From eye to V1 (geniculo-striate pathway) Optic
nerve Optic Chiasm Lateral Geniculate Nucleus
(LGN) Primary Visual Cortex (V1)
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Vision loss from damage occurring at different
stages
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Ocular dominance columns
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Magno
Parvo
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Two Pathways What vs. Where (Ungerleider and
Mishkin) Perception vs. Action or What vs. How
(Goodale and Milner)
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action
What vs. where
perception

V1
Ungerleider and Mishkin, 1982
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Haxby et al, 1994
Milner Goodale, 1993
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Object-sensitive regions in human
brain (statistical map on inflated cortical
surface)
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interesting numbers The eyes are 6 cm apart and
half-way down the head Visual angle of the sun
or moon 0.5 deg At arm's length thumbnail
1.5 deg thumb joint 2.0 deg fist 8-10 deg
Monocular visual field measured from central
fixation 160 deg (w) x 175 deg (h) Binocular
visual field measured from central fixation 200
deg (w) x 135 deg (h) Retinal size 5 cm x 5
cm 0.4 mm thick Size of each area V1 3cm by 8
cm Half of area V1 represents the central 10
deg (2 of the visual field) Highest detectable
spatial frequency at high ambient light levels,
50-60 cpd low ambient light levels, 20-30 cpd
Highest detectable temporal frequency high
ambient large field, 80 Hz low ambient, large
field 40 Hz. Visible spectrum 370-730 nm.