Impairment and Recovery of Song Syntax in Bengalese Finches: Implications for Learning and Vocal Motor Production

Abstract

Songbirds are an appealing animal model for human speech acquisition partially due to the fact that both species are vocal learners, meaning they acquire their vocalizations through imitation. The Bengalese finch song is semi-variable. Some syllable-to-syllable combinations are fixed, whereas some syllables can be followed by multiple syllables. In songbirds, there are two different neural system, one which is responsible for song acquisition and one that regulates song production. The premotor nucleus HVC (letters are proper name) is essential for both pathways to function normally. In this study, I explored whether HVC contributes to maintaining and recovering song syntax, as well as potential differential effects of lefts versus right HVC microlesions. To answer these two questions, the syntactic structures of previously collected songs were analyzed at three different time points: baseline (pre-surgery), post-surgery day 4 (PSD4), and post-surgery day 7(PSD7). The results support previous findings that HVC lesions disrupt vocal production and suggest novel syllables are the result of impaired motor control. These results also suggest that control of song syntax is somewhat lateralized in Bengalese finches. Left HVC microlesions initially impair the birds' ability to produce a stereotyped song by making syllable transitions more variable. Therefore, the right HVC controls song variability, and left HVC song stereotypy.