The neural response of female zebra finches (Taeniopygia guttata) to conspecific, heterospecific, and isolate song depends on early-life song exposure.

The auditory forebrain regions caudo-medial nidopallium (NCM) and caudo-medial mesopallium (CMM) of songbirds exhibit differential expression of the immediate-early gene ZENK in response to playback of different song stimuli, and dependent on early-life auditory experience. Similarly, song preferences depend both on auditory experience and unlearned biases for particular song features. We explored the contributions of early-life auditory experience and the type of song stimuli on the Zenk response in the auditory forebrain of female zebra finches. Females were raised in three different early tutoring conditions: conspecific tutors that sang isolate song, heterospecific tutors, or conspecific tutors that sang wild-type song. At maturity, these females were exposed to one of five different playback conditions: wild-type song, isolate song, tutor song, heterospecific song, or white noise. Subsequently, the number of cells immunoreactive for ZENK in CMM and NCM was measured. We predicted that birds exposed to conspecific song early in life, and during the song playback in adulthood, would have the highest neural response. Instead, we found that the Zenk response varied across playback conditions with the highest response to conspecific wild-type and conspecific isolate song. In addition, we found a main effect of tutoring, with the lowest overall Zenk response in females tutored by males singing isolate song. Most importantly, there was a significant interaction in that females tutored by wild-type conspecific or heterospecific songs showed a similar increased response to zebra finch songs (wild-type or isolate), but females tutored by isolate song showed no differential response to conspecific song and only showed elevated Zenk response to the particular songs they were tutored with. Combined, our results indicate that unlearned response biases to conspecific song elements depend on previous auditory experience. That is, early experience appears to modulate the expression of innate biases.