Delayed extinction of executive sets associated with decreased cholinergic function: a mechanism of perseverative and intrusive behavior.

Perseverative and intrusive behavior were studied in three psychiatric patients with toxic dementia associated with anticholinergic drugs. A mechanism was proposed attributing these behaviors to the delayed extinction (residual activation) of prior executive sets (or schema) in the context of sets containing nondissociated operations. Reutilization of these operations appeared to trigger the nonextinguished set back into executive status. It was hypothesized that set perseveration and intrusion reflect a defect in the set-scheduling process induced by loss of cholinergic function.