Frontal cortex as the site of action of physostigmine in nbM-lesioned rats

The administration of a variety of cholinomimetic agents to nucleus basalis of Meynert-lesioned rats has been shown to alleviate their lesion-induced memory deficits. This experiment attempted to determine whether the frontal cortex was the site of the memory enhancing action of the cholinomimetic physostigmine. Different groups of rats received excitotoxic lesions of the basal forebrain, the frontal cortex or both. Immediately after one trial passive avoidance training, these rats were injected with either saline or a 0.06 mg/kg dose of physostigmine. Physostigmine enhanced the 72-hour retention test performance of sham-operated and basal forebrain-lesioned rats, but failed to affect the performance of rats with cortical lesions. These data were interpreted as consistent with the hypothesis that the memory-enhancing effects of physostigmine are at least partially mediated by the frontal cortex.