Cerebral preparation of spontaneous movements: An EEG study.

OBJECTIVE

The current study sought to determine whether there is a Bereitschaftspotential (BP) before uninstructed, spontaneous movements.

METHODS

14 participants were seated on a comfortable armchair for one hour without any instruction except not to fall asleep and to keep their eyes open. Electroencephalography (EEG) and electromyography (EMG) activity were recorded during the whole session. EEG activity was analyzed before spontaneous movements and compared with EEG activity before repetitive, instructed movements in a separate session.

RESULTS

BPs were identified in most participants with the spontaneous movements. The BPs with spontaneous movements were mostly localized in the medial frontocentral regions. The BPs with the instructed movements were localized primarily in the central regions and had larger amplitude.

CONCLUSION

Presence of a BP before movement does not depend on instruction and may be independent of conscious volition. The amplitude of the BP may depend on the amount of attention.

SIGNIFICANCE: This study shows that the presence of a BP before movement is not an "artifact" of the experimental instructions.