An adapting auditory-motor feedback loop can contribute to generating vocal repetition

TL;DR

This study reveals that an adaptive auditory feedback loop influences vocal repetition in songbirds, with feedback strength diminishing over repetitions, affecting sequence generation and neural responses.

Contribution

It introduces a novel model of adaptive auditory feedback influencing vocal repetition, supported by computational and experimental evidence in Bengalese finches.

Findings

Deafening reduces syllable repetitions.

Neural responses adapt during repeated sequences.

Auditory feedback influences vocal sequence generation.

Abstract

Consecutive repetition of actions is common in behavioral sequences. Although integration of sensory feedback with internal motor programs is important for sequence generation, if and how feedback contributes to repetitive actions is poorly understood. Here we study how auditory feedback contributes to generating repetitive syllable sequences in songbirds. We propose that auditory signals provide positive feedback to ongoing motor commands, but this influence decays as feedback weakens from response adaptation during syllable repetitions. Computational models show that this mechanism explains repeat distributions observed in Bengalese finch song. We experimentally confirmed two predictions of this mechanism in Bengalese finches: removal of auditory feedback by deafening reduces syllable repetitions; and neural responses to auditory playback of repeated syllable sequences gradually adapt in sensory-motor nucleus HVC. Together, our results implicate a positive auditory-feedback loop with adaptation in generating repetitive vocalizations, and suggest sensory adaptation is important for feedback control of motor sequences.