[Dependence of adaptation behavior of receptor neurons on current intensity]

The slowly adapting stretch receptor neuron exhibits a marked spike adaptation. In the present paper the dependence of the adaptation time constants and other parameters from the stimulus intensity or the stationary discharge frequency was investigated. In general, the adaptation in response to an intracellular current step is sufficiently approximated by the sum of two exponential terms. A transformation of the parameters measured to a feed back subsystem, which describes the effect of the ionic pump, was performed, too. Proceeding from these data, a generalizing conclusion is that the time constants decrease nearly hyperbolically with increasing stationary impulse frequency. This results in a nearly constant product of carrier frequency and adequate time constant. With regard to the degree of adaptation a marked saturation characteristic appears. In qualitative terms, these effects have to be explained mainly by the properties of the ionic pump and its dependence on the concrete in concentrations.