Basal forebrain stimulation modifies auditory cortex responsiveness by an action at muscarinic receptors.

We have hypothesized that auditory cortex plasticity involves modification of thalamocortical transmission by basal forebrain (BF) cholinergic neurons, and that this action may involve muscarinic receptors. In a first test of this hypothesis, we report that BF stimulation can suppress or facilitate, depending on the intensity of stimulation, auditory cortical responses elicited by thalamic stimulation. BF-mediated facilitation is antagonized by atropine, implicating muscarinic receptors. These data suggest that BF cholinergic neurons functionally modify auditory cortex by regulating thalamocortical transmission.