Bereitschaftspotentials and the frequency and phase characteristics of the EEG preceding bimanual finger movements

A delayed response paradigm was used to investigate the cerebral electroencephalographic (EEG) signal preceding bimanual finger flexions of continuously increasing and decreasing movement rates. The Bereitschaftspotential displayed larger amplitudes at faster required response rates as did two spectral frequency modes, which also showed magnitude reversals depending on the initiating finger. Furthermore, at these specific frequency modes, the averaged relative phase between electrode locations C3 and C4, as well as the variance in this measure was found to correspond closely to the variance in inter-response times derived from the subjects' movements. The results suggest the existence of possible signatures on the neurophysiological level which may yield information regarding the efficacy and parametric properties of the impending movement.