Synchronized gamma oscillations (30-50 Hz) in the amygdalo-hippocampal network in relation with seizure propagation and severity.
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.
Lévesque
Maxime
M
Centre de Recherche du Centre Hospitalier Universitaire Sainte-Justine, 3175 Côte-Sainte-Catherine, Montréal, QC H3C 1T5, Canada.
Langlois
J M Pierre
JM
Lema
Pablo
P
Courtemanche
Richard
R
Bilodeau
Guillaume-Alexandre
GA
Carmant
Lionel
L
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
D007608:Kainic Acid