Synchronized gamma oscillations (30-50 Hz) in the amygdalo-hippocampal network in relation with seizure propagation and severity

Neurobiol Dis. 2009 Aug;35(2):209-18. doi: 10.1016/j.nbd.2009.04.011. Epub 2009 May 12.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amygdala / physiopathology*
  • Analysis of Variance
  • Animals
  • Cerebral Cortex / physiopathology
  • Hippocampus / physiopathology*
  • Kainic Acid
  • Microelectrodes
  • Neural Pathways / physiopathology
  • Periodicity*
  • Rats
  • Rats, Sprague-Dawley
  • Seizures / chemically induced
  • Seizures / physiopathology*
  • Severity of Illness Index
  • Time Factors

Substances

  • Kainic Acid