Repeated generalized audiogenic seizures induce plastic changes on acoustically evoked neuronal firing in the amygdala

Brain Research
Hua Jun Feng, C L Faingold

Abstract

Repetition of audiogenic seizures (AGS) (AGS kindling) results in increases in the duration of convulsive behavior and the emergence of cortical epileptiform EEG activity. These changes involve expansion of the neuronal network subserving these seizures. The amygdala (AMG) is postulated to become involved in this expanded network, but the neurophysiological basis of this process is unknown. The present study examined changes in chronically-recorded extracellular neuronal firing patterns in the lateral nucleus of AMG (LAMG) induced by AGS kindling in behaving genetically epilepsy-prone rats (GEPR-9s). Before AGS kindling, onset-only (36.1%), onset-delayed (50%) and delayed-only (13.9%) patterns of response to acoustic stimuli were observed. Neuronal firing was greatly suppressed following systemically administered uncompetitive NMDA antagonist (ketamine, 30 mg/kg, i.p.) with complete recovery by 4 h. After AGS kindling, LAMG neurons displayed a significantly increased incidence of onset-only patterns (93.3%, at 0.5 Hz), and mean acoustic responsiveness was also significantly increased (516.2% of control). LAMG neurons fired tonically during tonic convulsions and exhibited burst firing during post-tonic clonus. Greater acoustical...Continue Reading

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