Coherence of sequential movements and motor learning.

The analysis of oscillatory EEG phenomena such as interregional coherence (task-related coherence [TRCoh] or event-related coherence) has advanced our knowledge of neurophysiological processes underlying the performance and learning of skilled finger movements. It has become clear that various types of higher task demands are reflected by changes in the functional coupling of different cortical areas and not only by changes in regional activation. Neuroscientists are merely starting to understand how coherent oscillations might encode information in the human motor system ("sensorimotor binding") and how well this can be measured from the surface EEG. However, interregional coherence is a potentially independent mechanism that can, up to now, only be investigated with electrophysiological techniques such as EEG and MEG. The studies reviewed below focus on coherence of finger movements and motor learning: increasing complexity of a movement sequence, internal rhythm generation, visuomotor integration, deficits in interhemispheric coupling, and bimanual coordination. Evidence is presented for a special functional significance of TRCoh in the beta frequency range (13 to 21 Hz) for information processing in large-scale sensorimotor networks during motor tasks.