A nonlinear encoder in crayfish sustaining fibers

Abstract The properties of the voltage to spike train encoder in crayfish visual interneurons are characterized with steps and sine waves of current and illumination. Impulse trains elicited by current steps exhibit rapid adaptation and encoder adaptation contributes to a rate sensitive frequency response in which the gain increases with stimulus frequency and the impulse rate modulation phase leads the current. Similar results obtain in the relation between impulse rate modulation and the synaptic potential. We conclude that encoder adaptation is the basis of the encoder's high sensitivity to voltage transients and describe the relevance of both the transient sensitivity and the tonic discharge at synapses made by the same neurons.