The effect of acetylcholine and dopamine on the caudate spindle in cats

Electrocortical activity was reacorded in cats whose caudate nuclei were perfused and electrically stimulated using a push-pull cannula. Electric stimulation invariably induced spindles (10-14 Hz) in the ipsilateral frontal cortex. Perfusions of acetylcholine together with physostigmine reduced the number of spontaneous spindles, the response to electric stimulation and induced behavioural arousal. This effect was atropine-sensitive. Perfusions of dopamine with or without tranylcypromine had no significant effect on the number of spontaneous spindles or the response to electric stimulation. Injections of both acetylcholine and dopamine into the cuadate nucleus invariably induced spontaneous spindles and slow waves. The significance of acetylcholine and dopamine in the caudate nucleus intiating caudate spindles and their significance in controlling arousal is discussed.