认知心理学课件何生

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'认知心理学课件何生'
Neural Correlates of Visual Awareness Sheng He University of MinnesotaLGN V1Physical Perceptual stimuli experienceDifferent Same stimuli percept Same Different stimuli perceptsPhysical Localized Perceptual stimuli neural activity experience different same ?? Areas in which activities change with stimuli are not good candidates of NCC.Physical Localized Perceptual stimuli neural activity experience same different moving ?? static Areas in which activities change with perception are good candidates of NCC.Physical Localized Perceptual stimuli neural activity experience same different rivalry or ?? Areas in which activities change with perception are good candidates of NCC. orPart I: adaptation to invisible stimuli (with Don MacLeod)Part II: motion aftereffect (with Eric Cohen, Xiaoping Hu)Part III: binocular rivalry -- parallel pathways to visual awareness (with Tom Carlson) Part I: adaptation to invisible stimuliPhysical Localized Perceptual stimuli neural activity experiencedifferent Can neurons in area X same tell the difference? Areas in which activities change with stimuli are not good candidates of NCC.Physical Localized Perceptual stimuli neural activity experience V1?? can cause orientation-selective adaptation?Sensitivity Unresolvable Spatial frequency (cycles/degree) Resolution limit: 50cpd Orientation-Selective Adaptation Same Orientation Hard to see! Need high contrast Orthogonal OrientationAdapt Easy to see! Need low contrast TestTilt-aftereffectV1 is the first stage in the visual system where orientation information is extracted: ? orientation-selective adaptation is only possible at or after V1. ? If we find evidence for orientation- selective adaptation, then it implies that the orientation information has at least reached V1. Result Same Orientation Need higher contrastInvisible vertical grating Orthogonal Orientation Adapt Need lower contrast Test test a. adapt or respond/adapt ? ? 5000 250 250 250 250 ms ms ms ms ms b. SH orientation DM orientation discrimination discrimination log sensitivity 1.2 orientation-specific orientation-specific adaptation adaptationfor orientation 1.0 unresolvable unresolvable discrim ination and 0.8 log threshold 0.6elevation from orientation- 0.4 specific 0.2 adaptation test test 0 30 35 40 45 50 55 60 65 70 30 35 40 45 50 55 60 65 70 (adapting) spatial frequency (cpd) (adapting) spatial frequency (cpd) He and MacLeod,Nature 2001 fig. 1Orientation-selective adaptation from an invisible spatial pattern: ? invisible to the observer but visible at V1. ? There is intra-cortical loss of spatial information. ? V1 activity is not sufficient for visual awareness. Part I SummaryFine spatial patterns can be “visible” at V1 but invisible to the observer. V1 activity is not always correlated directly with visual awareness.Caveats:1. Maybe no single area will be “sufficient” for visual awareness. This approach may lead to the rejection of the whole brain as NCC.2. Individual cortical area may not
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