Fig. 2.

In situ hybridizations of singing-regulated genes. Shown are inverse images of autoradiographs; white is mRNA expression. Images are ordered from top to bottom according to four overall expression patterns and from left to right in temporal order of peak expression. Some genes (egr-1, c-fos, c-jun, and Arc) were induced by singing in the smaller vocal nuclei (NIf, Av, and MO), but we could not reliably assess this for all genes. Egr-1 is shown to the left of the brain diagram (Bottom Right) for anatomical reference. A, arcopallium; Av, avalanche; DM, dorsal medial nucleus; LX, lateral AreaX of the striatum; LMO, oval nucleus of the mesopallium; N, nidopallium; NIf, interfacial nucleus of the nidopallium; P, pallidum; RA robust nucleus of the arcopallium; St, striatum. (Scale bar, 2 mm.)