An analogue model of the luminosity-channel in the vertebrate cone retina. 1. Hardware and responses to square wave voltages.

An analogue simulation was built of the vertebrate cone retina based on the model of Siminoff [J. Theor. Biol. 86, 673 (1980)]. Linear operational amplifiers were used for a few simple processes such as summation, integration (for synaptic delay), inversion and gain. Spatial and temporal properties of retinal elements were developed by interaction of simulated retinal neurons. Tonic and phasic ganglion cells were formed from the center-surround antagonistic receptive fields of bipolar cells. Center field input voltages favored the static levels of tonic units, while surround field input voltages favored the phasic units. Properties of receptive fields of retinal neurons could be simulated by the model using 2 antagonistic input voltages, one of which had a longer synaptic delay. Negative feedback from horizontal cells to cones and its potentiation by electrical coupling of horizontal cells reinforced overshoot produced by surround field input voltages with its extra synaptic delay as compared to the center field input voltage. In spite of simplifications, the model was a good representation of some properties of the retina.