Fig 5. Parvalbumin (PV) luminance is modulated by singing in HVC and Area X.

PV luminance in HVC-lat and Area X differed between non-singing birds (NS; gray bars) and singing birds (female-directed singers, FD; dark green bars; undirected singers, UD; light green bars). Bars represent means, while circles correspond to individual data points. * indicates a significant difference at p<0.05, # indicates a trend toward a difference at p<0.10.