Suppression of kindling behavior

Kindling behavior culminating with clonic convulsions is produced by 60-Hz sine-wave stimulation of the amygdala. This behavior can be suppressed by stimulation of the same site with 1-Hz or 3-Hz sine waves. Such results have been obtained consistently over many experiments with the manipulation of a number of variables. Suppression appears to be a transient process in that rats will return approximately to their prestimulation thresholds following 2 weeks or more of rest. The severity of suppression is greatest with 120 s or more of sine-wave stimulation and when the intertrial interval is 1 or 3 hours. The effect decreases at 24 hours; at 72 hours, 5 days, and 14 days, it appears to be minimal or nonexistent. These results suggest that tissue damage is not the basis for suppression. Further evidence for this interpretation is provided by results indicating that suppression of kindled behavior is complete and permanent with a single trial of DC stimulation (which produces tissue damage), in contrast to 1-Hz stimulated rats, which show a slow, gradual increase in threshold values over many trials and a strong recovery from the suppression later on.