Cholinergic blockade in prefrontal cortex and hippocampus disrupts short-term memory in rats.

The muscarinic antagonist scopolamine was injected into the prefrontal cortex and hippocampus of rats that were well trained in an operant delayed non-matching to position task. Cholinergic antagonism in the hippocampus induced dose- and delay-dependent deficits, characteristic of impaired short-term retention. By contrast, cholinergic antagonism in the prefrontal cortex induced dose-dependent but delay-independent deficits, suggesting disturbance of some non-mnemonic regulatory process in the neocortex.