The effects of probability and relative direction on human somatomotor electroencephalographic rhythms

Classical views on the preparation of voluntary movement involve separate motor and cognitive processes. Recent neurophysiological evidence challenges this dichotomy. Recordings from within the motor cortices have demonstrated that cognitive factors modulate neural activity. This issue was examined in event-related desynchronizations (ERDs) by using a goal-directed pointing paradigm. The ERD, which is typically recorded in response to self-paced finger movements, has been demonstrated to reflect specific movement parameters. Cognitive factors were introduced by manipulating probability and the relative direction of the responses in a choice reaction time task. The results demonstrated that probability influences the 20 Hz ERD. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.