Lowered thresholds to flurothyl seizures after lateral geniculate lesions in rats

Although considerable attention has been directed towards the effects of cerebral cortical damage on convulsive thresholds, few studies have involved subcortical structures. In the present report, the thresholds for flurothyl-induced myoclonic jerks and generalized seizures were determined in adult, male albino rats. Bilateral lesions of the lateral geniculate nucleus resulted in an almost 20% decrease in threshold to the convulsant. Although no sensitivity changes resulted from lesions of either the lateral thalamic posterior nucleus or the medial geniculate nucleus, lesions of these areas potentiated the effects seen with lesions of the lateral geniculate nucleus alone. In all cases, the increased sensitivity to the convulsant required more than 1 week after surgery for development. It was concluded that the visual system is intimately involved in at least some types of convulsive phenomena.