Fig. 1.

Song control circuitry including neuronal phenotypes of striato-pallidal Area X. Sagittal schematic illustrates major components of the song control system. The basal ganglia nucleus dedicated to vocal learning, Area X, is shown as the target of stereotaxic injections with viruses that encode fluorescent reporter proteins. Abbreviations are described in the list. Below, the basic neuronal phenotypes that comprise Area X are shown (Farries and Perkel 2002; Farries et al. 2005; Goldberg and Fee 2010a, b)