title: Synchronized gamma oscillations (30-50 Hz) in the amygdalo-hippocampal network in relation with seizure propagation and severity.
abstract: In this study, we demonstrate that gamma oscillations (30-50 Hz) recorded in the local field potentials (LFP) of the hippocampus are a marker of temporal lobe seizure propagation and that the level of LFP synchrony in the amygdalo-hippocampal network, during these oscillations, is related to the severity of seizures. Sprague-Dawley rats were given a single systemic dose of kainic acid (KA; 6 mg/kg, i.p.) and local field potential activity (1-475 Hz) of the dorsal hippocampus, the amygdala and the neocortex was recorded. Of 135 ictal discharges, 55 (40.7%) involved both limbic structures. We demonstrated that 78.2% of seizures involving both the hippocampus and amygdala showed hippocampal gamma oscillations. Seizure duration was also significantly correlated with the frequency of hippocampal gamma oscillations (r2=0.31, p<0.01) and LFP synchrony in the amygdalo-hippocampal network (r2=0.21, p<0.05). These results suggest that gamma oscillations in the amygdalo-hippocampal network could facilitate long-range synchrony and participate in the propagation of seizures.
authors.affiliation: Centre de Recherche du Centre Hospitalier Universitaire Sainte-Justine, 3175 Côte-Sainte-Catherine, Montréal, QC H3C 1T5, Canada.
authors.forename: Maxime
authors.initials: M
authors.lastname: Lévesque
authors.forename: J M Pierre
authors.initials: JM
authors.lastname: Langlois
authors.forename: Pablo
authors.initials: P
authors.lastname: Lema
authors.forename: Richard
authors.initials: R
authors.lastname: Courtemanche
authors.forename: Guillaume-Alexandre
authors.initials: GA
authors.lastname: Bilodeau
authors.forename: Lionel
authors.initials: L
authors.lastname: Carmant
mesh_terms: D000679:Amygdala / Q000503:physiopathology*; D000704:Analysis of Variance; D000818:Animals; D002540:Cerebral Cortex / Q000503:physiopathology; D006624:Hippocampus / Q000503:physiopathology*; D007608:Kainic Acid; D008839:Microelectrodes; D009434:Neural Pathways / Q000503:physiopathology; D010507:Periodicity; D051381:Rats; D017207:Rats, Sprague-Dawley; D012640:Seizures / Q000139:chemically induced / Q000503:physiopathology*; D012720:Severity of Illness Index; D013997:Time Factors
chemical_list: D007608:Kainic Acid