Somatosensory evoked potentials to median nerve (MN) stimulation were recorded by stereotactically implanted electrodes in the frontal lobe of two epileptic patients in order to evaluate whether short-latency cortical responses could be generated in the supplementary motor area (SMA)-proper. In both patients two potentials, called P20 and N30 responses, showed a decreasing amplitude from the most superficial to the deepest contacts and were recorded in the white as well in the grey matter of the frontal lobe. Furthermore, no phase reversal of both P20 and N30 potentials was identifiable along electrode trajectories. Our results suggest that short-latency somatosensory evoked responses recorded in the SMA-proper contralateral to MN stimulation are volume conducted from remote cortical generators.
- Evoked potentials
- Intracranial recordings
- Somatosensory evoked potential
- Supplementary motor area-proper
ASJC Scopus subject areas