Bilaterally symmetrical respiratory activity during lateralized birdsong

Area of Science:

• Animal behavior
• Neuroscience
• Bioacoustics

Background:

• Birdsong production is a complex behavior involving intricate coordination between respiratory and vocal systems.
• The syrinx, the avian vocal organ, exhibits lateralized control during song production in some species.
• Understanding the neural control of respiration during vocalization is crucial for deciphering motor command distribution.

Purpose of the Study:

• To investigate the relationship between expiratory muscle activity and lateralization in birdsong production.
• To determine if expiratory muscle activation is bilateral or lateralized during vocalization in brown thrashers.
• To compare the motor control of respiratory muscles with that of the syrinx.

Main Methods:

• Assessed respiration and syringeal motor activity in brown thrashers.
• Monitored bilateral airflow and subsyringeal air sac pressure.
• Recorded electromyographic activity of expiratory abdominal muscles and vocal output.

Main Results:

• Expiratory muscle activity was consistently bilateral, irrespective of unilateral or bilateral song production.
• The amplitude of expiratory electromyogram (EMG) on one side did not change significantly even when that side was silent.
• Bilateral EMG bursts correlated with syringeal airflow rate changes, even when airflow was generated by only one syrinx side.

Conclusions:

• Motor commands to expiratory muscles are bilaterally distributed during birdsong.
• This bilateral respiratory control contrasts with the lateralized motor control observed in the syrinx.
• Findings suggest a divergence in neural pathways controlling respiration and vocalization during birdsong.