ACh-induced long-lasting enhancement in excitability of the olfactory bulb.

This study tested whether acetylcholine (ACh) could induce long-term modifications in neuronal excitability in the main olfactory bulb (OB). In anaesthetized rats, perfusion in the region of the mitral cell body layer was done with a push-pull cannula and the neuronal excitability was appraised through evoked field potentials (EFPs) elicited by stimulation of the laternal olfactory tract. Application of ACh (1 mM) for 15 min following a 10 min period of infusion with picrotoxin (GABAA antagonist, 0.4 mM) induced a large enhancement in the antidromic response of output cells which lasted for several hours. This result suggests that the cholinergic projections from the basal forebrain could be involved in processes supporting durable changes in OB response to odours.