Analysis of Local Field Potential and Single-unit Firing Patterns during Spontaneous Seizures in Human Hippocampus and Insular Cortex

GORI B; GRANADO M; BLENKMANN A; KOCHEN S

Chicago

Congreso; Neuroscience 2015; 2015

Society for Neuroscience

We studied the spatiotemporal scale of focal epilepsy and the spread of epileptogenesis.We used wide-bandwidth electrophysiological intracranial recordings using clinical macro(cM)- and research microelectrodes (rM) in patients with epilepsy.We analyzed 23 spontaneous seizures of 2 patients with insular epilepsy (IE) and frontalepilepsy (FE). For further analysis, we only included 11 seizures that showed a local fieldpotential (LFP) with single units (SU) activity during ictal period and at least within 15 minbefore seizure onset.LFP and SU were recorded across multiple days. In IE case,microelectrodes were localized within the epileptogenic zone (EZ) in posterior ínsula.However, seizures recorded from cM were not simultaneously observed in adjacent rM.LFP during seizures did not showed epileptiform discharges and FR remained constant ordecreased. In FE case, rM were outside of EZ (hippocampus) and when seizures spread tothe hippocampal area, cM recorded epileptiform discharges that were simultaneouslyobserved on LFP. In this case, a marked increase in FR was observed. The areas involveddirectly in the seizure or its propagation that showed hypersynchronous discharges on LFP,presented an increased in FR. While LFP did not show epileptiform discharges in spite ofbeing part of EZ, FR only show low-level. These findings could have important implicationsfor how we localize seizure activity and how we map its propagation.