Pre-motion positivity during self-paced movements of finger and mouth.

The present study investigated the role of pre-motion positivity in movement initiation and the reason why it is not reliably detectable in every study participant. Nineteen right-handed participants performed self-initiated simple movements of the right index finger and mouth while electroencephalography activity was recorded. Most of the participants showed a clear-cut pre-motion positivity with its characteristics varying as a function of the effector involved in the movement. The pre-motion positivity distribution was ipsilateral for finger movements and symmetrical for mouth movements. The results suggest that pre-motion positivity might represent a go-signal to initiate the movement and its occurrence might depend on movement initiation strategies.