Enhanced population responses in the basolateral amygdala of kainate-treated, epileptic rats in vitro

Several lines of evidence suggest that the amygdala is altered functionally in humans with temporal lobe epilepsy, but little is known about neuronal interactions in the amygdala of humans or animals with chronic epilepsy. Using extracellular and intracellular recordings in horizontal slices, we tested the hypothesis that changes in local circuitry in the basolateral amygdala (BLA) permanently enhance neuronal responsiveness in kainate-treated, epileptic rats. Population responses in the BLA to orthodromic stimulation were significantly enhanced, which was at least partly due to a decrease in local inhibition. In the presence of GABA receptor antagonists, population responses were about twice as robust in epileptic versus control rats. We conclude that the enhanced neuronal responsiveness of the BLA in this model of temporal lobe epilepsy involves decreased inhibition, but may also include increased excitation.