Lecture_12 - The Central Visual System Fig 10.4-Retinal...

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10/13/05 The Central Visual System Fig. 10.4 - Retinal fugal - comes from retina to go somewhere else. .. toward visual cortex - Optic nerve (actually a tract)- convergence of axons from photoreceptor - Optic chiasm - partial decussation. .. half of the axons project contralateral (nasal side)the other half project ipsilateral (peripheral side) - Optic tract (after the chiasm)- some terminate in the super chiasmic nucleus (circadian rhythm), superior colliculus (midbrain), lateral geniculate nucleus (LGN) - LGN is the main target of axons -sends signal to cortex, second order neurons projet from LGN to cortex - Visual cortex is in occipital lobe Visual Field - combination of what you see with both eyes - overlapping field = binocular visual field. .. gives you depth perception - Left or Right periphery - only seen by one eye. .. monocular - Fixation point - where you focul - Right or left hemifield - Right side of brain only sees the left hemifield and vice versa Visual Field Deficits fig 10.5 -IF you CUT the left optic nerve (a) you no longer see left periphery -IF you CUT the optic tract (b) you only see one hemifield -TRANSECTION of optic chiasm (nothing crosses over, no decussation) (c) you loose some depth perception and all periphery Retinotopic Map fig 10.7 -Some fibers go to superior colliculus. .. points on the retina project to nerves that are in the same order in brain systems Lateral Geniculate Nucleus (LGN) fig 10.8 -Has corresponding points to retina (retinotopic map) -6 layers- line up visual fields -->Segregation in LGN is maintained fig 10.9
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This note was uploaded on 04/28/2008 for the course ZOL 402 taught by Professor Eisthen during the Fall '05 term at Michigan State University.

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Lecture_12 - The Central Visual System Fig 10.4-Retinal...

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