Disrupting vagal feedback affects birdsong motor control

Area of Science:

• Neuroscience
• Bioacoustics
• Animal Behavior

Background:

• Song production in oscine songbirds relies on complex motor coordination and feedback mechanisms.
• Auditory feedback's role in song maintenance is established, but other feedback systems remain understudied.
• Somatosensory feedback, potentially via the vagus nerve, is implicated in regulating respiratory pressure during song.

Purpose of the Study:

• To investigate the impact of unilateral vagotomy on the motor patterns and acoustic features of song production in songbirds.
• To elucidate the role of vagal (somatosensory) feedback in maintaining vocalizations.

Main Methods:

• Unilateral vagotomy was performed on songbirds to disrupt vagal nerve function.
• Peripheral motor patterns of respiration during song were analyzed.
• Acoustic features of the resulting vocalizations were measured and compared.

Main Results:

• Unilateral vagotomy led to significant disruptions in the respiratory patterns controlling song.
• Acoustic structure of songs was altered, indicating changes in sound generation and vocal tract filtering.
• Effects were most pronounced in the initial days post-surgery and varied individually, with severe cases disrupting song syllables and motifs.

Conclusions:

• Vagal feedback plays a critical role in the real-time motor control of song production, distinct from auditory feedback.
• Disruption of vagal feedback impacts multiple motor systems involved in vocalization, including respiration, sound generation, and filtering.
• This study underscores the importance of somatosensory feedback in learned vocal behavior and motor programming.