F07Homework2Answers-1 - CS17 F07 Name HOMEWORK 2 PERCEPTUAL...

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CS17 * F07HOMEWORK 2Name______________________________PERCEPTUAL SYSTEMSAcross Fiber CodingWhen a stimulus is coded through the RATIO of response across multiple cellsConvergence (or Summation)When multiple pre-synaptic cells all communicate to one post-synaptic cellDivergenceWhen one presynaptic cell communicates to many post-synaptic cellsReceptive FieldSet of receptors whose actitvity influences the activity of target cellExcitatory Center- Inhibitory SurroType of above: stimulating center increases target response, non-center decreases itTopologicalType of map that preserves spatial relaitonships (as along a sensory surface)MagnificationIn cortex, disproportionate enlargement of the rep. of a sensory area of low convergenceModuleAn area of the brain specialized for processing one particular type of informationThe Binding ProblemThe problem posed by having several of the above, and yet perceiving wholesVISIONRetinaRear layers of neurons in the eyeballReceptors (Rods & Cones)Cells that respond to light; show spontaneous, graded release of inhibitory NTRodsAbove that are convergent, sensitive to motion & low light, mainly in peripheryConesAbove that connect few:1, sensitive to color & detail, dispersed & conc'd in centerFoveaCentral area of above receptors only, connected 1:1 for highest acuityBipolarsNext cell in pathway, spontaneous, graded potentials, release excitatory NTHorizontalsInter-neurons that modify reaction of above, implicated in color opponencyGanglionsNext cell in pathway, action potentials, release excitatory NTOptic NerveFormed of axons of the aboveOptic DiscPlace where above leaves eye for brain, also called "Blind Spot"AmacrinesInter-neurons that modify reaction of above, implicated in contrast effectsDark CurrentFlow of Na* in/out of receptor, in absence of light > spontaneous release of NTCa++Ion that enters receptor, causing chain reaction that results in release of NTDimLevel of light (bright or dim?) that results in greatest release of NT from receptorsBrightLevel of light (bright or dim?) that results in greatest release of NT from bipolarsAcuityHigh-detail discrimination, as from low convergence, that retains info on diffsSensitivityHigh likelihood of detection, as from high convergence that crosses next cell's thresholdLateral InhibitionCell activity resulting in release of inhibitory NT to cells orthogonal to info pathway Simultaneous ContrastIllusion created by above that alters perception of central grey depending on its surround Uni-directionalDirection of inhibition (uni- or bi-directional?) in direction-senstive motion circuitLateral Geniculate Nuc or LGNNucleus in Thalamus that processes most visual information from eyeColumnIn cortex, set of cells, in 6 layers, that all respond to the same preferred stimulusHyper-ColumnIn cortex, set of cells that all have same RF and include set of orientation cols & blobsRetinotopic MapTopological map that preserves spatial relationships found on RetinaA1 or Striate Cortex

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