The Journal of Neuroscience, February 1, 2002, 22(3):1177-1186
Short-Term and Long-Term Effects of Vocal Distortion on Song
Maintenance in Zebra Finches
Gerald E.
Hough II and
Susan F.
Volman
Department of Evolution, Ecology and Organismal Biology, Ohio State
University, Columbus, Ohio 43210-1293
Adult zebra finch song is irreversibly altered when birds are
deprived of correct feedback by deafening or denervation of the syrinx.
To clarify the role of feedback in song maintenance, we developed a
reversible technique to distort vocal output without damaging the
auditory or vocal systems. We implanted flexible beads adjacent to the
syrinx to alter its biomechanics. Immediate song aberrations included
low volume, frequency shifts, missing harmonics, and production of
click-like syllables. After a few weeks, seven of nine birds stopped
producing some syllables. In six of these birds, the gaps left by the
silenced syllables gradually shortened, and the lost syllables did not
return when beads were removed 16 weeks after treatment began. The
nondeleted syllables of all birds regained their preimplant morphology,
insofar as could be detected, within 9 d after bead removal. In
four other birds, we removed the beads as soon as syllables were
deleted, when the silent intervals were still full length. In these
birds, all deleted syllables returned within 1 week. Our results
indicate that both silenced syllables and syllable morphology can
recover as long as the song's temporal structure is maintained, but
once altered, changes in the song sequence can be permanent. A
hierarchical organization of the song production system has recently
been described (Margoliash, 1997). Reversible disruption of song
production by our method appears to permanently alter the higher levels
of the system that encode song sequence, but not the lower levels that encode individual syllable structure.
Key words:
zebra finch; auditory feedback; vocal distortion; song; HVc; songbirds; vocal learning
Copyright © 2002 Society for Neuroscience 0270-6474/02/2231177-10$05.00/0