Vision- Striate CortexRetinotopy-Slide 3Slide 43 Main Types of Retinal Ganglion CellsOrganization of the LGNSlide 7Slide 8Slide 9Slide 10Slide 11Slide 12Dorsal and ventral streamsSummaryVision- Striate Cortex•How does the visual system go from center-surround receptive fields in the retina to very complex representations of the world?–How is information organized in the lateral geniculate nucleus (in the thalamus)?–How is information organized in layer IVC of the striate cortex?–What kinds of receptive fields do we find in the striate cortex?–How is information processed outside of the striate cortex?Retinotopy-The area of the fovea compared to the rest of the retina is relatively small. Does this mean that the images projected onto the fovea occupy a proportionally small area of the visual cortex?a) Yes, it will be proportionalb) No, it will be smallerc) No, it will be larger3 Main Types of Retinal Ganglion Cells•M-type:–Large receptive fields–Very sensitive to light–Important for detection of movement•P-type:–Small receptive fields–Some respond to color–Important for detection of shape•Non-M-non-P:–Not well studied–Important for color detectionOrganization of the LGNLGN inputs to the striate cortex-ocular dominance columns and blobsInformation integration outside of layer IVC of the striate cortex- binocular receptive fieldsInformation integration outside of layer IVC in the striate cortex -orientation selectivity (simple cells)simple cell response:input2input1input321 321 3simple cell3 overlapping receptive fields:21 3Information integration outside of layer IVC in the striate cortex-direction selectivity (simple cells)Complex cell responds to particular orientationof visual stimulus throughout entire receptive fieldsimple cell 1simple cell 2simple cell 3Information integration outside of layer IVC in the striate cortex-complex cellsDorsal and ventral streamsSummary•LGN (thalamus)–Center-surround receptive fields•Layer IVC (striate ctx)–Center-surround receptive fields•Other layers (striate ctx)–Simple cells•Orientation selective•Direction selective–Complex cells•Visual streams–Dorsal stream- “where” pathway–Ventral stream- “what”
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