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Visual Cortex

Visual Cortex. Vision Science Lectures in Ophthalmology Curtis Baker. receptive fields of retinal ganglion cells. KSJ, Fig 26-7. retina-LGN-cortex. KSJ, Fig 27-4. V1 neurons: orientation selectivity. KSJ, Fig 27-11. V1 neurons: direction selectivity. -. -. +. +. -. -. -. -. +.

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Visual Cortex

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  1. Visual Cortex Vision Science Lectures in Ophthalmology Curtis Baker

  2. receptive fields of retinal ganglion cells KSJ, Fig 26-7

  3. retina-LGN-cortex KSJ, Fig 27-4

  4. V1 neurons: orientation selectivity KSJ, Fig 27-11

  5. V1 neurons: direction selectivity

  6. - - + + - - - - + + - - - - + + + + - - - - - - - - + + - - + + - - - - - - + + - - - - + + - - - + - + + - + - - - - - - - + + - - + - + - - - neurons as stimulus filters wrong spatial frequency simple cell receptive field wrong orientation optimal grating

  7. ocular dominance columns KSJ, Fig 27-16

  8. CCD Camera Population responses: optical imaging Stimulus Generator Illuminator Real-time Video Processor Data Collection and Analysis (courtesy of Chang’an Zhan)

  9. orientation columns KSJ, Fig 27-14

  10. cytochrome oxidase blobs KSJ, Fig 27-15 • input from LGN koniocellular layers • in centers of ocular dominance columns • receptive fields: non-oriented, colour-opponent

  11. retinotopic map in V1 KSJ, Fig 27-9

  12. retinotopic maps from fMRI Sereno et al, 1995

  13. field sign maps Sereno et al, 1995

  14. extrastriate visual areas larger receptive fields, less retinotopy functional specializations single units: Zeki, V4 vs MT/V5 brain imaging: stimuli that selectively activate (e.g., motion/flicker -> MT/V5) KSJ, Fig 25-9

  15. dorsal & ventral streams: many extrastriate areas KSJ, Fig 28-2

  16. dorsal and ventral streams: neurophysiology KSJ, Fig 25-12

  17. effects of damage striate cortex (V1) -> blindness V2 -> "quadrant" blindness other extrastrate areas -> selective losses, e.g.: MT / V5 -> motion-blindness FFA (fusiform face area) -> prosopagnosia fusiform cortex ("colour area" ?) -> achromatopsia

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