Analysis of Local Field Potential and Single-unit Firing Patterns during Spontaneous Seizures in Humans.

GORI B; GRANADO M; BLENKMANN A; COLLAVINI S; KOCHEN S

Mar del Plata

Congreso; XXX Congreso Anual de la Sociedad Argentina de Investigación en Neurociencias (SAN); 2015

Sociedad Argentina de Nuerociencia (SAN)

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 frontal epilepsy (FE). For further analysis, we only included 11 seizures that showed a local field potential (LFP) with single units (SU) activity during ictal period and at least within 15 min before 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 or decreased. In FE case, rM were outside of EZ (hippocampus) and when seizures spread to the hippocampal area, cM recorded epileptiform discharges that were simultaneously observed on LFP. In this case, a marked increase in FR was observed. The areas involved directly 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 of being part of EZ, FR only show low-level. These findings could have important implications for how we localize seizure activity and how we map its propagation. 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 frontal epilepsy (FE). For further analysis, we only included 11 seizures that showed a local field potential (LFP) with single units (SU) activity during ictal period and at least within 15 min before 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 or decreased. In FE case, rM were outside of EZ (hippocampus) and when seizures spread to the hippocampal area, cM recorded epileptiform discharges that were simultaneously observed on LFP. In this case, a marked increase in FR was observed. The areas involved directly 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 of being part of EZ, FR only show low-level. These findings could have important implications for how we localize seizure activity and how we map its propagation.