Скачать презентацию The Human Visual System Background on Vision Скачать презентацию The Human Visual System Background on Vision

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The Human Visual System • Background on Vision • Human vision – the best The Human Visual System • Background on Vision • Human vision – the best system around • Deep network models

Hemifield neglect Hemifield neglect

Eye Eye

Recording Spikes Recording Spikes

Receptors Density - Fovea Receptors Density - Fovea

Image Capture • • • Huge dynamic range 10 -8 – 10+6 μW/cm 2 Image Capture • • • Huge dynamic range 10 -8 – 10+6 μW/cm 2 Photons: poisson process. Noisy at low levels For low light: large receptors, slow integration Rods/cones, local adaptation, change of amplitude and time constant, motion deblur

Poisson Distribution Poisson Distribution

Adaptation Effect Adaptation Effect

Dynamic Range Dynamic Range

Visual receptor types Visual receptor types

Retina Mosaic Retina Mosaic

Color Mixing Color Mixing

Retina Output: Ganglion Receptive Fields Output = image * Do. G Retina Output: Ganglion Receptive Fields Output = image * Do. G

Cortex Cortex

Bi-directional Computation Bi-directional Computation

Physiological Recording Physiological Recording

Orientation Selectivity Orientation Selectivity

V 1: Direction selectivity Modified from PSY 280 F V 1: Direction selectivity Modified from PSY 280 F

Visual Areas Visual Areas

Contours and Boundaries (V 1, V 2) Contours and Boundaries (V 1, V 2)

Stimuli tested in V 2, V 4 Stimuli tested in V 2, V 4

Neuronal Responses, V 2 Neuronal Responses, V 2

Stimuli tested in V 2, V 4 Models (SIFT, Ho. G) do not represent Stimuli tested in V 2, V 4 Models (SIFT, Ho. G) do not represent such features

Tanaka IT clusters Kiani, et al J. Neurophysiol 2007 Object Category Structure in Response Tanaka IT clusters Kiani, et al J. Neurophysiol 2007 Object Category Structure in Response Patterns of Neuronal Population in Monkey Inferior Temporal Cortex.

f. MRI Magnet f. MRI Magnet

f. MRI Activation Slice f. MRI Activation Slice

f. MRI Activation f. MRI Activation

(Fusiform (red, yellow (Fusiform (red, yellow

Face-Pace Rivalry Face-Pace Rivalry

House-Face f. MRI Transitions Rivalry differences similar to monocular but less pronounced Activity is House-Face f. MRI Transitions Rivalry differences similar to monocular but less pronounced Activity is higher for the perceived stimulus Dominance is partial, significant activity for the non-dominant stimulus.