Schematic of Bilaterally Organized Song-Control Areas in the Zebra Finch Brain

The output of the song system is formed by the tracheosyringeal portion of the hypoglossal nucleus (nXIIts), by inspiratory nucleus parambigualis (PAm), and by the expiratory nucleus retroambigualis (RAm), bottom. These motor areas receive input from cerebral song-control areas HVC and LMAN via RA (all shown in blue). There are two thalamic pathways for indirect interhemispheric communication between cerebral song-control areas: (1) via the nucleus uvaeformis (Uva) and (2) via the dorsomedial posterior nucleus (DMP). Areas with efferent projections to the contralateral hemisphere are marked in red, full lines show direct connections, and dashed lines show indirect connections. DM: dorsomedial nucleus of the intercollicular complex. Stimulation electrodes were implanted in HVC and LMAN (dark blue arrows).