Transcript Cortex
The visual system IV The visual cortices The primary visual pathway From perret-optic.ch Primary vision Structure of the primary visual cortexThe headquartes Information flow Intra V1 1 Higher areas 2/3 Intra V1 4a Higher areas 4b 4cα 4cβ M P 5 Superior colliculus, pulvinar, pons 6 LGN, thalamic interneurons Visual columnsRFs and orientations 200 μm Orientation map How does orientation selectivity arise? Ferster et al. (1996), Reid & Alonso (1996) Receptive fields in different cortical layers Layers IV and VI Simple cells Layers II and III Complex cells Are complex cells more complex, or just more active? Complex cell! Adapted from Kandel et al. (2000) Are complex cells more complex, or just more active? Crowder et al. (2007) Higher visual areas: The Where and What Magnocellular! Parvocellular! Higher visual areas: Inferotemporal cortex Fusiform face area Halle Berry Cells Halle Berry Contour perception is fed back to V1 Lamme (1995) Higher visual areas: The Where and What Magnocellular! Parvocellular! Motion perception is fed back to V1 Muckli et al. (2005) Summary IV – The visual cortex… • continues the segregation in magno- and parvocellular pathway as the Where and What pathway •is segregated into six layers, all of which fulfill different tasks in coordinating activity from the thalamus, other cortical areas and the brain stem • is organized in response preference columns, according to ocular dominance, stimulus orientation, contrast, length etc. • contains neurons with simple and complex responses •is in constant feedback-feedforward loops with the Where and the What pathways