Involvement of the cholinergic mechanism in depression of the caudate spindle.

Involvement of the cholinergic and catecholaminergic mechanisms in the caudate spindle recorded from the anterior and posterior sigmoid gyri was examined in cats. Physostigmine (0.01 to 0.1 mg/kg i.v.) abolished the appearance of the caudate spindle. These inhibitory effects were antagonized by the administration of atropine (0.25 to 1 mg/kg i.v.). The caudate spindle was inhibited by high frequency stimulation of the mesencephalic reticular formation: This inhibitory effect was antagonized by atropine. On the other hand, L-DOPA (25 to 50 mg/kg, i.v.), L-DOPA + MAO inhibitor and methamphetamine (0.5 to 5 mg/kg i.v.) did not influence the caudate spindle. These results suggest an involvement of cholinergic mechanism in depression of the caudate spindle.