Ketamine hydrochloride and its effect on a chronic cobalt epileptic cortical focus.

The effects of anesthetic and nonanesthetic doses of ketamine hydrochloride were studied in male adult rats in which a primary and a projected epileptic focus were induced with implantation of cobalt in the right or left frontal cortex. Electrical activity was recorded from the frontal, parietal, and occipital cortices. Nonanesthetic doses of ketamine were associated with activation or enhancement of primary and projected focal electrical activity, as well as turning behavior toward the side of the cobalt focus. Anesthetic doses of ketamine also enhanced or activated the primary and projected foci. These animals demonstrated turning behavior toward the side of the cobalt focus prior to and following the cataleptoid state. During catalepsy, forelimb twitching and oscillating movements of the vibrissae occurred. The activation of primary and projected foci by ketamine at anesthetic and nonanesthetic doses supports the clinical findings that ketamine is epileptogenic in certain patients with a seizure disorder.