 - Epileptic patients must have clinically documented partial seizures, in either the left or right temporal lobe, or generalized seizures with consistent EEG evidence as defined by the 1981 International Classification of Epileptic Seizures, refractory to standard antiepileptic treatment for at least one year. This criterion will be established by preliminary screening in the NINDS CES outpatient clinic, and, where previous studies are not adequate, by inpatient video-EEG monitoring. 