Bereitschaftspontential during the acquisition of a skilled motor task.

Bereitschaftspontential (BP) research typically uses very simple, abrupt movements that require no learning and which change little over the duration of the experimental session. The present study investigated changes in the size and cortical distribution of the BP during the acquisition of a skilled motor task. Twelve subjects were employed. Electrodes at FZ, CZ, C3'' and C4'' were used to record the EEG with DC amplifiers. A series of 6 button presses in a specified pattern constituted the motor task. Subjects were instructed to press the series every 20 sec as quickly as possible, but with no errors. Significant response time, electrode and trial main effects, and electrode by trial interactions were found. The BP increased steadily at all electrodes as performance improved, i.e., as response time decreased. After the response reached asymptote the BP recorded at FZ and C4'' decreased, while the BP at CZ and C3'' remained relatively constant. Multivariate analyses of covariance showed a consistent relationship between the improvement in response times and the changes in the BP. This study demonstrates that the size and cortical distribution of the BP are systematically related to improved proficiency of a motor response with learning.