Electrophysiological aspects of interictal and ictal activity in human partial epilepsy

Considerable attention has been paid in recent times to cellular and synaptic mechanisms involved in epileptogenesis. A number of in vivo and in vitro animal models are now available to study basic mechanisms of epileptogenesis and to select and evaluate antiepileptic compounds which could be potentially effective in human epilepsy. Although this approach has been useful for practical purposes, conceptual implications of epileptogenesis and neurophysiology in general, there is still a gap in the understanding of human epilepsy in the light of basic mechanisms of epileptogenesis. This appears to be particularly true for partial epilepsy since animal models are usually generated by environmental factors which are not common causes of partial epilepsy in humans and cellular aspects of human epileptogenesis have only been studied in very particular circumstances 1-3. The chronic implantation of intracranial electrodes in epileptic patients being assessed for surgery allows the study of ictal and interictal electrical activity from regions which are usually inaccessible to scalp recordings. Apart from their primary purpose in the localization of epileptic loci, the study of human intracranial recordings can provide an insight into some electrophysiological aspects of human epileptogenesis and provide a bridge between the reductionist approach of cellular animal studies and the noninvasive approach of more standard electrophysiological studies in humans. A particularly important problem in human partial epilepsy is the identification and delimitation of the epileptogenic zone (that region of tissue the removal or