The tune of songbirds is a complex skill, produced in highly stereotyped fashion from one rendition to the next. Juveniles learn their song over a period of months, first memorizing their fathers tune and then, weeks later, embarking on a period of vocal exploration, in which they initiate their fledgling renditions while comparing them to the memory of their fathers tune, laid down in their neural circuitry. This process, using auditory feedback, involves a continuous fine-tuning of the birds melody, culminating in a stable, nearly crystallized, song.
Adult songbirds, meanwhile, rely on auditory feedback to maintain their song, and previous studies by Brainard have shown that if the birds are deaf, or receive garbled auditory feedback via a computer-based intervention, the fidelity of their song gradually deteriorates.
Scientists have not known, however, whether modulation in adult birdsong can be driven, in a predictable way, through auditory feedback. In the current study, the team examined this possibility.
They used a computerized system to monitor small natural variations in the pitch of targeted elements of the birds song, and then delivered disruptive auditory feedback to a subset of the vocalizations, or syllables. The disruption was in the form of a short burst of white noise - a static chh!-chh-chh! sound. Higher pitched renditions received a short burst of white noise, while lower pitched versions were left undisturbed.
The response was nearly immediate. Birds receiving the white noise feedback rapidly shifted the pitch of their vocalizations to avoid the sound. The changes were restricted precisely to the targeted syllable. It was quite dramatic, says Tumer. We were able to make the bird sing a particular syllable with a higher pitch.
This data provides the first evidence that you can take this really stereotyped behavior that people have assumed was crystallized
|Contact: Jennifer OBrien|
University of California - San Francisco