Claustral lesions delay amygdaloid kindling in the rat

Purpose: Lesions of the claustrum in cats and primates have been shown to d isrupt the development and expression of amygdaloid-kindled seizures in cat s and primates. Because the structure and connectivity of the claustrum can vary between species, we wanted to examine the effects of claustral lesion s on kindling in rats. Methods: One group of rats received bilateral radiofrequency lesions of bot h anterior and posterior regions of the claustrum before amygdaloid kindlin g. Another group of rats received bilateral anterior and posterior radiofre quency lesions of the claustrum after amygdaloid kindling. Some rats were t ested for transfer of kindling to the contralateral amygdala after claustra l lesions. Results: Small lesions that destroyed 13% of the claustrum were capable of delaying, but not blocking, amygdaloid kindling. The delay in kindling was due to an increase in the stimulation trials required to kindle to stage 5 seizures. The lesions had no effect on established kindled seizures or on t ransfer to the contralateral amygdala. Conclusions: As in other species, the claustrum in the rat appears to play a role in kindling from the amygdala. Because of the restricted size of our claustral lesions, however, we were unable to conclusively assess the full extent of the claustrum's participation in limbic kindling.