Neuron

Neurons Purkinje cells from cerebellum, dendrites showing calcium concentration

Synaptic connection

Eye

Neural circuitry of the retina

Receptors Density - Fovea

Photoreceptors

Photoreceptors

CCD Well Photon can come from the left or right, depending on the device. It creates an electron-hole pair in the silicon (need about 1.14 ev). The electrons migrates in the N type silicon layer, and creates a voltage difference across the metal-oxide capacitor.

Image Capture Huge dynamic range 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

Visual receptor types

Spectral sensitivity

Color Mixing

Center-surround Receptive Fields Modified from PSY280F

LGN Layers

Physiological Recording

Orientation Selectivity

V1: Direction selectivity Modified from PSY280F

End-stopped cell

Simple Cells

Visual Areas

Bi-directional Computation Forward: to layer 4, backward: avoid layer 4. Rich, and usually reciprocal. Most models: feedforard, or full connectivity. Could have important computational implications, but the exact nature of these computations remain for future empirical and computational studies.

fMRI Magnet

fMRI Activation Slice

fMRI Activation