Movement-related potentials during the performance of a motor task II: Cerebral areas activated during learning of the task

Movement-related potentials (MRPs) recorded from the brain are thought to v ary during learning of a motor task. However, since MRPs are recorded at a very low signal-to-noise ratio, it is difficult to measure these variations . In this study we attempt to remove most of the accompanying noise thus en abling the tracking of transient phenomena in MRPs recorded during learning of a motor task. Subjects performed a simple motor task which required lea rning. A modified version of the matching pursuit algorithm was used in ord er to remove a significant portion of the electroencephalographic noise ove rlapping the MR-Ps recorded in the experiment. Small groups of MRPs were th en averaged according to experimental parameters. Our results show that the power of the MRPs does not decay uniformly during learning. Instead, there is a significant peak in their power after 4 or 5 repetitions of the task. This peak is noticeable especially in electrodes placed over the prefronta l region of the cortex at times subsequent to the actual movement. The obse rved pattern of activity may indicate problem solving related to comprehens ion of the force against which the user performed the task. It is possible that this problem solving occurs in the prefrontal cortex.