First trial motor seizures triggered by amygdaloid stimulation in the rat

Several different patterns of electrical stimulation were applied to the amygdala of the rat for 10 min in order to determine: (1) if first trial generalized convulsions could be triggered; and (2) which parameters were most effective for triggering first trial convulsions. It was found that motor seizures could be triggered and that low frequencies (16–24 p/sec) were most effective, whether presented in the form of continuous pulses or pulse trains.The pattern of stimulation did not appear to affect the amount of seizure susceptibility subsequently shown by these subjects. They were, however, more susceptible to seizures than a previously nonstimulated group as shown by their faster rate of seizure development during repeated stimulation (kindling).It was also shown that the range of stimulation frequencies that were found to be most effective for triggering first trial seizures was similar to the range of frequencies which produced “recruiting” in the hippocampus during amygdala stimulation. Possible mechanisms were discussed.