Components of the visual system. The individual neuron.
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Components of the visual system
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Transcript of Components of the visual system. The individual neuron.
Components of the visual system
The individual neuron
Neuron
Neurons
Purkinje cells from cerebellum, dendrites showing calcium concentration
Synaptic connection
Synapse
The Eye
The main aspects are the photoreceptors, which is the input layer, and the ganglion cells, the output layer to the brain
Eye
Neural circuitry of the retina
Receptors Density - Fovea
Photoreceptors
Photoreceptors
Visual receptor types
Spectral sensitivity
Color Mixing
Dynamic Range
Center-surround Receptive Fields
Modified from PSY280F
Edge-detection by zero-crossings
Some theory, and the relation to ganglion cells .
Edge Detection by Z.C.
Peak in f’(x) z.c. in f’’(x) Noise: Asin(wx) > -w2cos(wx) Convolve with a Gaussian (optimal) d2/dx2(G*f) = d2/dx2(G) * f
In 2-D: d2/dx2 + d2/dy2
Edge Detection by Z.C.
Z.C. at Two Scales
Wheel Edges 4 Resolutions
LGN Layers
The Cortex
The main topics are: area V1 in some details, response properties of cells in V1, how they are
organized in the area .General properties of higher level visual areas .
Physiological Recording
Orientation Selectivity
V1: Direction selectivity
Modified from PSY280F
End-stopped cell
Simple Cells
Visual Areas
Bi-directional Computation
Stimuli tested in V2, V4
From: Tanaka, 1996
Columnar modules of region TE
fMRI Magnet
fMRI Activation Slice
fMRI Activation
