Non-singing female Bengalese Finches (Lonchura striata var. domestica) possess neuronal projections connecting a song learning region to a song motor region

Bengalese Finches Lonchura striata var. domestica are extremely sexually dimorphic in their singing behavior; males sing complex songs, whereas females do not sing at all. The brain nuclei that control song in males are many times larger than those in females are, except the lateral portion of the magnocellular nucleus of the anterior nidopallium (LMAN), which comprises the same volume in both sexes. In this study, we examined the connectivity of the LMAN in female Bengalese Finches using a biotinylated dextran amine (BDA) in vivo tracing technique. We found that efferent connections of the female LMAN projected mainly to the robust nucleus of the arcopallium (RA), although the RA in female Bengalese Finches is much smaller than in males. Our data demonstrate that non-singing female Bengalese Finches possess projections connecting a song learning region to a song motor region. These connections may have functional roles in song perception.