SUMMATION OF EXCITATION IN RECEPTIVE FIELDS OF MOVEMENT-SENSITIVE NEURONS OF FROGS RETINA

The receptive field of movement detecting class-2 neurons of the frog's retina is composed of an excitatory receptive field center (ERF) and an inhibitory receptive field periphery (IRF). The summation of activation elicited by two black stimuli moving against a white background through the ERF was measured. The action potentials of optic nerve fibers in the superficial layers were recorded by means of microelectrodes. The average impulse frequency during the ERF-transverse was varied by changing stimulus velocities. The average impulse frequencies elicited by movement of each stimulus alone did not summate algebraically, if two stimuli were moved simultaneously through the ERF. The results indicate that for the summation of neuronal signals within the ERF a superimposition of lateral excitatory processes and lateral inhibition occurs. © 1969.