Influence of central cholinergic pathways on performance on free-operant avoidance and DRL schedules.

Lesions in the medial septum, as well as systemic injections of the muscarinic cholinergic blocker, scopolamine, increased responding maintained by free-operant avoidance or DRL contingencies. Systemic injections of the anticholinesterase, eserine, suppressed responding in both paradigms. The medial septal lesions eliminated the effects of these cholinergic drugs in the DRL paradigm byt did not reduce the effects of these drugs on free-operant avoidance. These results indicate that cholinergic drugs may affect behavior in the DRL paradigm primarily by acting on muscarinic cholinergic neurons that pass through the septum but affect free-operant avoidance mainly by acting on different cholinergic pathways that do not pass through the medial septum.