[Central cholinergic system innervates song control system of songbirds and regulates song behavior]

Songbird has become an ideal model for studying motor learning due to its unique learned song behavior. It has been proved that song behavior is directly regulated by song control system in the forebrain of songbirds. There are lines of evidence to show that cholinergic transmitters and their receptors are distributed in song control system, and vocal control nuclei in song control system are innervated by cholinergic nerves from the central cholinergic system in basal forebrain, which can affect activities of vocal control nuclei through cholinergic transmitters, and then affect song behavior. Studies in mammals have confirmed that the central cholinergic system is involved in the regulation of motor behavior and neural process of motor learning. Elucidation of regulation of songbirds' song behavior by central cholinergic system would shed light on the neural mechanism of song motor control and song learning and memory in songbirds, and provide theoretical insights for researches on other animals' sensorimotor processes and human language learning. This review summarized recent progresses, including the research work of our laboratory, in the studies on the selectivity of cholinergic transmitters to their receptors and their effects on neuronal activities in vocal control nuclei of songbirds and provided valuable clues for revealing the regulation mechanism of central cholinergic system on songbirds' song behavior.