INTRACEREBRAL RECORDING OF MOVEMENT-RELATED READINESS POTENTIALS - ANEXPLORATION IN EPILEPTIC PATIENTS

Readiness potentials (RPs) preceding voluntary self-paced limb movemen ts were recorded intracerebrally in 13 patients suffering drug resista nt, intractable epilepsy. Multilead depth electrodes were positioned u sing the Talairach's coordinate system; they allowed simultaneous reco rding from the external and mesial cortices and from the interposed wh ite matter during self-paced unilateral hand or plantar flexions. Our intracerebral explorations have shown RPs in the primary motor cortex (MC) contralateral to the movement and in both supplementary motor are as (SMAs), indicating that at least 3 cortical sites become active bef ore the movement. At variance with the scalp RPs recorded in the same patients, the intracerebral potentials were either negative, or positi ve, depending on the recording site. No consistent differences in dura tion and time of onset could be established between the MC and the SMA RPs, at least with the used time resolution. RPs were only occasional ly observed in the parietal cortex and hippocampus and none were recor ded from the amygdala, the temporal, temporo-occipital, prefrontal, fr ontal and cingular cortices. The wide topographical distribution of th e scalp RPs may not be fully explained by the above intracortical find ings, leaving the possibility that other generators exist, whose locat ions remain to be determined.