Stereotypy and Variability Predict Interruptibility of Zebra Finch Song

Abstract

Motor preparation deficits are a feature of many neurological disorders in humans. Developing animal models to study deficits in motor preparation is essential to explore the potential therapeutic treatment avenues. In male zebra finches (Taeniopygia guttata), song is composed of a fixed syllable sequence and is preceded by a series of introductory notes. It is thought that introductory notes may be a preparatory motor program, but this has not been experimentally tested. We aimed to differentiate preparatory motor periods from song execution by interrupting female-directed song and song produced in isolation (undirected song) with white noise playback. The amplitude and duration of the white noise were systematically varied along with when the playback occurred during song. We hypothesized that interruption events would occur more frequently during the preparatory phase of song production. Song respiratory motor gestures were measured in six birds experiencing the noise disruption events. During both directed and undirected song, playback disrupted the typical syllable progression seen in undirected song without playback (control condition). Interruption events occurred at the highest frequency during introductory notes compared to other points in the song motif. Higher frequencies of interruption also occurred with higher amplitudes or longer durations of white noise. Ascertaining patterns of stereotypy and variability in zebra finch vocalizations can elucidate where in song motor program preparation leads to execution. The results suggest that introductory notes are a form of motor planning for the execution of the song motor program. These data illustrate that the zebra finch song is an excellent model system for exploring how motor planning deficits manifest in language and communication disorders.