Temporary inactivation of NCM, an auditory region, increases social interaction and decreases song perception in female zebra finches.

The caudomedial nidopallium (NCM) is an important site for the storage of auditory memories, particularly song, in passerines. In zebra finches, males sing and females do not, but females use song to choose mates. The extent to which the NCM is necessary for female mate choice is not well understood. To investigate the role of NCM in partner preferences, adult female zebra finches were bilaterally implanted with chronic cannulae directed at the NCM. Lidocaine, a sodium channel blocker, or saline (control) was infused into the NCM of females using a repeated measures design. Females were then tested in 3 separate paradigms: song preference, sexual partner preference, and pairing behavior/partner preference. We hypothesized that lidocaine would increase interactions with males by decreasing song discrimination and that this would be further evident in the song discrimination task. Indeed, females, when treated with lidocaine, had no preference for males singing unaltered song over males singing distorted song. These same females, when treated with saline, demonstrated a significant preference for males singing normal song. Furthermore, females affiliated with males more after receiving lidocaine than after receiving saline in the pairing paradigm, although neither treatment led to the formation of a partner preference. Our results support the hypothesis that NCM plays an important role not only in song discrimination, but also affiliation with a male.