Studies on neuronal processes in the retina by antidromic' stimulation.

1) Action potentials in response to supermaximal stimulation of the optic tract were recorded by means of a microelectrode20-50 μ in diameter, placed at the inner surface of cat's retina. Two distinct negative spikes, CI and CIL were distinguished in the potential, each negative spike being preceded by a positive deflection. The average conduction velocity in the retina was found 3.9m/sec. for CI and 2.4m/sec. for CII.2) When a flash of light of a few msec. in duration was given prior to antidromic stimulation, the antidromic action potential was suppressed to various degrees, depending upon the interval between both stimuli. The suppression of CII developed more slowly than that of CI.3) The effect of wave-lengths upon the temporal pattern of suppression was investigated with colored lights of equal visual purple stimulation. The suppression showed wave-like fluctuations somewhat characteristic of the wavelength of the light used.4) Interaction between both stimuli was investigated on isolated single elements, and in some cases intracellular recordings were carried out.5) Based upon the knowledge obtained from single elements, various features of the suppression of compund antidromic potentials were discussed.