Pre- and post-movement oscillatory characteristics of the primary motor cortex in a whole-body sensorimotor task.

The currently available literature on movementrelated cortical processes is limited tosimple movements with small muscular activity.Considering the motor requirements ofdaily life activities as well as those in sports,these movements are not representative andcontrol processes may differ significantly inmore complex movements which usually involvea larger muscle mass and are moredynamic. The present study analyzed corticalactivity as measured by electroencephalography(EEG) during a whole body sensorimotormovement task. 12 subjects performed 30counter-movement jumps. EEG was recordedover the sensorimotor areas of the cortexand analyzed using band-pass-Filters. Alpha,beta and gamma frequency bands weredefined based on individual frequency characteristics for four segments containing the pre- and post-movement period, respectively. For statistical analysis log-transformed electrical power values were calculated for the electrodes overlying the functional leg/footregion of the primary motor cortex. We founda desynchronisation (ERD) in the alpha andbeta frequency bands before movement whilepower values in all gamma frequency bandsremained unchanged. Immediately after landing,beta power returned to baseline valueswhile alpha power was still reduced for abouttwo seconds. Electrical power in all gammafrequency bands was elevated for about twoseconds. Moreover, we found broad bandeffects for all frequency bands rather thannarrow reactive frequencies. The results ofthe present study suggest common processesin the primary motor cortex preceding simple(small muscle mass) and complex (large musclemass) movements that are associated withpower changes in the alpha, beta and gammafrequency bands. These results were interpretedrelated to movement preparation aswell as to information transfer of propriceptive feedback.