[Muscle reflex responses to paired electrical stimulation of peripheral nerves].

Double-shock bifocal peripheral nerve stimulation with varying interstimulus intervals (ISI) was applied to healthy human subjects. Short (SLR) and long latency reflexes (LLR) from the slightly active first dorsalis interosseous muscle of the hand were recorded after an electrical conditioning stimulation of the index finger and test stimulation of the median nerve. It was found with intervals from 1 to 5 ms the size of the SLR and LLRs was smaller and unstable, possibly due to transmitter depletion at these short ISIs. With intervals of 10 ms and longer, the test responses progressively increased and were far larger than the control responses, probably due to some temporal summation with double-shock stimulation and some release of the transmitter substance after the conditioning cutaneous stimulus. (Fig. 3, Ref. 18.).