Long-term inhibition of kindled seizures by brain stimulation

Abstract

It was concluded from previous studies that prior stimulation produced a long-lasting inhibition of kindled seizures only when a series of convulsions were evoked. The present study describes a brain stimulation procedure capable of producing a long-lasting inhibition of kindled convulsions without evoking prior convulsions of EEG afterdischarge. Electrodes were implanted in the amygdala of rats, which were then kindled to a criterion of five successive tonic-clonic convulsions. After kindling, the animals were exposed to a regimen of intermittent amygdala stimulation, which was gradually increased in intensity in small incremental steps from a point just below the convulsion threshold to an intensity above the original kindling current. Using this procedure, it proved possible to administer high stimulation intensities without evoking any behavioral convulsions or EEG afterdischarges. Subsequent to this inhibitory procedure, amygdala stimulation did not evoke convulsions or EEG seizures for as long as 7 days. Additional studies tested the relative effectiveness of different stimulation rggimens and parameters for producing long-lasting inhibition of kindled seizures. The magnitude of the incremental intensity steps, the interstimulus interval, and the intensity of stimulation all proved to be relevent. We concluded that long-lasting inhibition of kindled seizures could be produced by prior stimulation that did not evoke seizures.