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S&P 070221 - antagonism – two types of cells each...

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Lateral Geniculate Nucleus (LGN) Input from ganglion cells (division of P & M cells maintained in LGN) Four outer layers receive inputs from P ganglion cells Two inner layers receive inputs from M ganglion cells Left and right LGN receives input equally from left and right eyes (contralateral and ipsilateral) No one neuron receives input form both eyes, therefore LGN is not responsible for depth perception – no binocular cells Retinotopic Map – within each layer of the LGN, the systematic representation of the retina that preserves neighborhood relationships. Spatial structure of retinal image is preserved. Each of the six layers contains a complete retinotopic map. Receptive Fields (RFs) of LGN cells Roughly circular, and also exhibit the same kind of center-surround antagonism as ganglion cells; also do not respond strongly to homogenous light intensity or differences in orientation Parvo cells are color-selective and exhibit of color opponency (a dual center/-surround
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Unformatted text preview: antagonism – two types of cells, each with agonizing/antagonizing color field) • (1)Red/Green; (2)Blue/Yellow • Parvo cells are more acute, with better resolution than mango cells, because their receptive fields are smaller • Magno cells respond better to movement Visual Cortex Primary Visual Cortex (PVC) – area of visual cortex that receives its inputs directly from the LGN. Also known as “V1” (first visual area), “striate cortex” (surface has striations), and “area 17” (based on older nomenclature) • Retinotopic Map in V1 • Cortical Magnification – 80% of cells devoted to central 10 degrees of vision. Each hemisphere represents contralateral visual field • 6 layers o Input from LGN enters via Layer 4 • Hubel & Wiesel – prior to their work, people had already figured out how ganglion d LGN cells respond to light using flashing spots of light • V1 cells are orientation-selective Superior Colliculis...
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