Fig. 5.

Reversal in the polarity of the cumulant density estimate between adjacent bipolar electrode sites. A, Case 2, Bipolar chain lying over the left sensorimotor cortex. The estimated position of the central sulcus is indicated by thevertical line. The electrode posterior to the central sulcus produced a motor response in the right extensor digitorum communis on stimulation. Coherence (B,C) and cumulant density estimates (D) calculated from signals recorded between the bipolar electrodes, which are indicated by arrows, and the right deltoid during tonic contraction. The cumulant density estimate corresponding toB is in gray and has been inverted to highlight polarity reversal.