Comparison of Bereitschaftspotential, Pre-motion Positivity and Motor Potential Preceding Voluntary Flexion and Extension Movements in Man

Abstract

This chapter discusses comparison of bereitschaftspotential, pre-motion positivity and motor potential preceding voluntary flexion and extension movements in man. That the precentral motor cortex is involved in control of movement rather than of individual muscles is an early concept. Recent results in primates suggest differences between flexion-related and extension-related motor cortex cells. Through the intact human skull, 3 different potentials can be recorded preceding voluntary finger movement, Bereitschaftspotential (BP), pre-motion positivity (PMP), and motor potential (MP). The MP is defined as an additional negativity starting on average 60msec prior to the first muscle action potential occurring in bipolar contralateral versus ipsilateral precentral leads. The MP is thought to reflect activation of the precentral motor cortex while generating the pyramidal tract volley. If this is true, the MP should share certain characteristics observed in recordings of single neurons in animals, including differences between flexion-dependent and extension-dependent motor cortex cells. The results suggest that the early preparatory process of the BP in the foreperiod of a voluntary movement is not basically different whether it precedes index finger flexion or extension of equal size.