An electronic model of the y-system of mammalian retina

Abstract

A set of detailed circuits are described that implement what we believe to be a reasonably faithful model of the y-system of the retina. The model is shown in block-diagram form in Fig. 1. It consists of: 1. An array of receptors, R, such as those described in DF5121. 2. A resistive network with capacitance to ground, modeling the horizontal cells. The horizontal resistors, H, provide lateral conductance that can be loosely thought of as a model of the gap-junctions between cells. The cell capacitances are modeled as lumped elements. 3. Triad synapses, TS, that take the difference between the potential of the horizontal network and that receptor output, and drag the local potential of the horizontal network along in the process. 4. Bipolar cells, B, that threshold the output of the triad synapses and carry the signal forward. 5. Amacrine cells, A, that sum an asymmetric surround of bipolar outputs. 6. Receptive field units, RFU, that apply the amacrine inhibition to the bipolar outputs. 7. A dendritic network, DN, in which a number of receptive fields are summed. 8. The Ganglion cell proper, G, that integrates the DN sum with respect to time, and issues an output pulse if the integral exceeds some threshold.

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