A spatio-temporal dipole model of the readiness potential in humans. I. Finger movement.

Preceding unilateral finger movements readiness potentials (RPs) were recorded in 9 right-handed subjects. The data are presented as time series, potential maps and spatio-temporal dipole models. The latter are interpreted with respect to the underlying generators of the RP. Explicit hypotheses about the unilateral or bilateral activation of particular sensorimotor areas preceding unilateral movements are addressed. The choice for the best spatio-temporal dipole model was guided by a test on the orthogonality of the individual residuals and by a priori neurophysiological evidence. From the final model it is concluded that the initial bilateral symmetrical part of the RP is generated in the posterior walls of the precentral gyrus bilaterally, whereas the later lateralized components originate from the crown of that same gyrus contralaterally. This confirms and extends data from subdural recording, magnetoencephalography (MEG) and EEG.