Retinal Circuit and Processing Overview of the retinal circuit Receptive field (RF) of retinal ganglion cells (RGC) Neural circuitry underlying the RGC receptive field From now on we’ll be talking a lot about RF, circuitry, and their relationship!

General organization of the visual pathway

Different cells in the retina The Basic Retinal Circuit Back of eye 6. Pigment cells 1. Receptor Cells (Graded potential) (input) 2. Bipolar Cells 3. Ganglion Cells (action potential) (Output) 4. Horozontal Cells (Graded potential) 5. Amacrine Cells (Graded/action potential) Structure of the eye Front of eye 2

light Fovea: high spatial resolution Periphery: low spatial resolution

Receptive field of RGC

Receptive field Definition: the area of the retina (or visual field) in which light signals evoke responses It’s a property of the cell, not a cell or a part of the cell It depends largely on the synaptic inputs to the cell and to some degree the biophysical property of the cell itself

Features of RGC center-surround interactions There are two types of RFs: ON center/OFF surround, OFF center/ON surround. Active inhibition of the center response with surround stimulation. 3) A maximal response can be evoked only with an optimally sized spot. A few other things Fovea: small RF, high resolution; Periphery: large RF, low resolution M cells: large RF, fast response, color blind; P cells: small RF, slower response, color sensitive.