Representative CB1 immunostaining. (A) Medial parasagittal sections contain rostral song regions lMAN and Area X, thalamic regions DLM and Ov, and cerebellum. (B) More lateral parasagittal sections capture HVC and RA. Dorsal and caudal are indicated by arrows, the bars = 1 mm. (C) A tracing of the micrograph in panel A serves as a diagram summarizing relative locations of song regions studied. Regions present in panel A are represented in black, other regions are diagrammatically represented in grey (HVC, RA and nXII). Established interconnections between song regions are indicated with arrows. Grey arrows indicate rostral forebrain circuitry essential for vocal learning. Black arrows indicate caudal vocal-motor circuitry.