Electrocorticographic effects of topically applied scopolamine

The electrocorticographic effects of topically applied scopolamine were investigated in unanesthetized cats with high cervical transection. After subpial injection of 30 cumu scopolamine in concentrations of 10 to 20%, large amplitude intermittent sharp waves appeared in the electrocorticogram, which developed into long-lasting paroxysmal activity. This effect was antagonized by intravenous eserine, 0.1 mg/kg, when it was produced by topical scopolamine in low dosage. The acoustically evoked cortical response and the generalized epileptiform activity produced by topical succinylcholine disappeared after topical scopolamine in low dosage. It is suggested that the seizure-suppressing effect of scopolamine may be due to its cholinolytic action. The convulsive activity of topical scopolamine in high concentrations may be accounted for by its depolarizing, synchronizing, disinhibiting, and acetylcholine-releasing effects.