NSCI 1051 Lecture Notes - Lecture 9: Agnosia, Two-Streams Hypothesis, Thalamus

• School: Temple University
• Department: Neuroscience - CLA
• Course: NSCI 1051
• Professor: Cynthia M Gooch

Document Summary

Optic nerve: retina to optic chiasm (info from one eye) Optic tract: chiasm to thalamus (info from both eyes) Lateral geniculate nucleus (lgn): nucleus in thalamus that is the target of projections. V1, primary visual cortex, striate cortex: receives info from lgn. Damage to the primary visual pathway can cause specific, predictable visual deficits. Hemianopsia = half the visual field is gone. Striate cortex (v1) is organized such that columns of cells (layer i vi) represent one eye or the other, with the borders between columns representing both eyes. Defined as a loss of color vision where patients remark that the world is drab and devoid of color. Retinal trichromatic mechanisms are intact (3 functional types of cones), but the processes that compare the output of these cones are now gone. This implies that there is a color center for the brain, probably in the inferior occipitotemporal region (ventral stream) Defined as an inability to recognize visual forms.