Development of a model of the premotor potential

This study explored the sensory nature of the small negative premotor potential (PMP) that is often seen preceding the compound muscle action potential. We developed a model of the PMP, using the ulnar and superficial radial sensory (SRS) nerves. Standard conduction studies of the deep ulnar motor nerve recording over the first dorsal interosseous manus (FDIM) and of the SRS nerve recording over the same site were done separately, then simultaneously, on 20 normal hands. In all subjects, there was no FDIM PMP, but with simultaneous stimulation of both nerves, there was a potential in all subjects that appeared similar to their median thenar and ulnar hypothenar PMPs. Reference data for the median thenar, ulnar hypothenar, and model PMP were generated. Findings from this study are discussed and appear to support the concept of the PMP being either a sensory potential or a junctional potential.