Figure 1.

Example of song-induced Egr-1 immunoreactivity. Photomicrographs show the caudolateral nidopallium (putative homologue of the prefrontal cortex; see Table 1) in estradiol-treated female white-throated sparrows listening to synthetic tones (A) or conspecific song (B). These examples depict the expression levels closest to each within-group median. Scale bar = 50 μm.