PowerPoint PresentationSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Contrast EffectRetina Cross SectionSlide 18Slide 191Perception - Overview1. The visual system, anatomy and physiology, visual features and their cortical representation.2. Feature search, visual illusions, constructive aspects of perception, bi-stable percepts.3. Deficits in visual feature perception, auditory perception.2The Problem of (Visual) PerceptionDavid Marr (1970s, 80s): Vision as an information-processing task, leading to a representation of the visual world somewhere in the brain.But: Visual stimuli are inherently ambiguous and context-dependent. Causes of visual images are hidden and must be inferred.3From: Purves and Lotto, “Why We See What We Do”45The Visual Pathway RetinaLateral Geniculate Nucleus (LGN)Visual Cortex67The Visual Pathway The eye8The Visual Pathway Layered organization of the retina9The Visual Pathway Inverring the number of cones:10The Visual Pathway Cones differ in their spectral sensitivity11The Visual Pathway What does the “raw image” in the retina look like?1213Mapping the Visual Field14LGN Layers15LGN Layers LGN map of retinal eccentricity16Contrast Effect17Retina Cross Section1819The Visual Pathway The (classical) receptive field: The region of a sensory surface (retina, skin) that, when stimulated, changes the membrane potential (firing rate, activity) of a neuron.Retinal ganglion cell receptive field structure: ON-center/OFF-surroundLGN receptive field structure:
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