PARIETAL EPILEPTIC MIRROR FOCUS DETECTED WITH A WHOLE-HEAD NEUROMAGNETOMETER

WHOLE-head magnetoencephalographic recordings revealed two parietal ep ileptic foci in homotopic areas of the hemispheres. The discharges occ urred 17-20 ms later on the left than on the right hemisphere, implyin g the existence of a left-sided mirror focus. The foci were about 1 cm posterior to the hand primary somatosensory area, identified by evoke d response measurements, and thus suggested epileptic activity at the parietal association cortex, in agreement with the observed callosal c onduction time.