Effect of correlated adjacent interspike interval sequences of the excitatory motor axon on the opening movement of the crayfish claw opener muscles

We examined how it affects the opening movement of the crayfish opener muscle whether successive interspike intervals of the excitatory motor axon are independent or not in the statistical sense. To execute this study, the excitatory motor axon was stimulated electrically with the three types of correlated adjacent interval sequences generated by digital-computer programs. The response of opening movement was subsequently analysed in relation to these statistical stimuli. The positive correlated interspike interval sequence (Type I) of stimulation prodeduced a larger movement amplitude than those of the other types (Type II; negative correlated sequence and Type III; independent sequence). The movement induced by Type II sequence fluctuated less about its moving average especially in a transient-state than those of the others. The differences of response fluctuations among the three types were evaluated for various mean values of the stimuli.