A neuronal analogue of state-dependent learning

State-dependent learning is a phenomenon in which the retrieval of newly ac quired information is possible only if the subject is in the same sensory c ontext and physiological state as during the encoding phase(1). In spite of extensive behavioural and pharmacological characterization(2), no cellular counterpart of this phenomenon has been reported, Here we describe a neuro nal analogue of state-dependent learning in which cortical neurons show an acetylcholine-dependent expression of an acetylcholine-induced functional p lasticity. This was demonstrated on neurons of rat somatosensory 'barrel' c ortex, whose tunings to the temporal frequency of whisker deflections were modified by cellular conditioning. Pairing whisker stimulation with acetylc holine applied iontophoretically yielded selective lasting modification of responses, the expression of which depended on the presence of exogenous ac etylcholine. Administration of acetylcholine during testing revealed freque ncy-specific changes in response that were not expressed when tested withou t acetylcholine or when the muscarinic antagonist, atropine, was applied co ncomitantly, Our results suggest that both acquisition and recall can be co ntrolled by the cortical release of acetylcholine.