psy290 lecs 5 (Chp7).pdf

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Junchul Kim

Sensory Systems 20121113 745 PM Sensationprocess where physicalchemical stimuli from external envbody are transformed into neural signals APbrain processes info about properties of stimuli 3 steps of sensation1 stimuli are captured by specialized cellso sensory receptor cellsdistinct sensory receptor cells for each sensory systemsensitive to specific stimulihave specialized structuresfunctions for sensory stimulitransductiono captured signals are transformed into neural signal APstimulation of sensory receptor cellsselective ion channels openresults in changing membrane potentialif integrated effect of local potential is large enoughstimuli triggers AP in sensory receptor cellneural signals passed to CNSo sensory neurons from sensory organsproject to spinal cordbrain o AP from sensory neurons synapse with other neurons in spinal cordbrainthen send signals to specific areas of cortex o signals go from sensory receptors to spinal cord via dorsal columndorsal colum nuclei medial lemniscusmedullathalamussensory cortex Sensory Receptor Cellsdistinct for each sensory systemsensitive to specific sensory stimulihave specialized structuresfunctions for diff sensory stimuliaxons of sensory receptor cells project to CNS Sensation vs Perceptionprocess of perceiving sensationperceptiono sensation is process of detecting presence of stimuliperception is higherorder process of o integrating o recognizing o interpreting complete patterns of sensation understanding the stimuli sensory system organizationreceptors o thalamic relay nucleiprimary sensory cortex ex lateral geniculate nucleusstriate cortexprimarysecondary sensory cortex of same systemsecondary sensory cortexmore than 1 sensory system mostly secondary sensory cortexassociation Hierarchical Organizationneurons respond optimally to stimuli of greater specificityo complexity as gores from receptors to association cortex 3 Features of sensory processingonce assumed primary secondary association areas of sensory system were functionally homogenouso all areas of cortical cortex at all levels acted together to perform same functionnow believed 3 featureso functional segregationfunctionally distinct areas specialize in diff kinds of analysis o parallel processingonce believed was serial system info flows among components over 1 pathwayparallel system info flows through components over multiple pathwaysparallel processing the simultaneous analysis of signal in diff ways by multiple parallel pathways2 kinds of parallel streams of analysis 1 capable of influencing behaviour without conscious awareness1 that influences behaviour by engaging conscious awareness o specificitycomplexity specificitycomplexity inc with each leveldamage receptors vs damaged sensory cortex if receptors can lose all sensation if sensory cortex lose particular sensations Model of Organizationhierarchical functionally segregated parallel division of laboro multiple specialized areas at multiple levels interconnected by multiple parallel pathwayseach area of system is specialized for perceiving specific aspectso ex visual system shapes colors movementmany neurons connect sensory hierarchyo most carry info from lower to higher o some higher to lower topdown signals Binding Problemhow to combine individual sensory attributes to produce integrated perception o solution1 single area of cortex at top of sensory hierarchy that receives signals from all areasputs together doesnt exist o solution2 perception is a product of combined activity of diff interconnected cortical areasAuditoryperception of sound of objectsevents through sounds they makesoundo vibrations of air molecules that stimulate auditory systemhuman hearingo bw 2020000 hertz cycles per second o can hear differences in pure tones that differ by 02 Soundamplitudeloudness
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