(A) During courtship (top), male Bengalese finches sing louder, faster, more stereotyped songs (black notes) to females compared to when they sing alone (grey notes; bottom). (B) Using a combination of local drug infusion and electrophysiological recordings, Jaffe and Brainard demonstrated that changes to song performance may depend on acetylcholine (Ach) acting in the premotor cortical nucleus HVC. When their HVC was stimulated with a drug mimicking acetylcholine (pink infusion; top panel), male finches produced songs similar to courtship songs, despite being alone. On the other hand, blocking acetylcholine naturally released in HVC during courtship singing (bottom panel) made the courtship song performance more similar to non-courtship song even when females were present. (C) HVC is connected to the robust nucleus of the arcopallium (RA) – a region involved in motor vocal output – both directly and through a cortical-basal ganglia circuit (gray box) that involves the basal ganglia nucleus (Area X), the dorsolateral anterior thalamic nucleus (DLM), and the lateral magnocellular nucleus of the anterior nidopallium (LMAN). Creating a lesion in LMAN (blue line) while stimulating HVC with acetylcholine preserved vocal vigor, showing that the neurotransmitter can act independently from the cortical-basal ganglia circuit.