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Laryngeal and respiratory activity during vocalization in macaque monkeys
1Institute for Neuroscience, Northwestern University, Evanston, Illinois 60208.
Summary
Macaque monkeys use specific laryngeal and respiratory muscles for distinct vocalizations like barks and coos. Muscle activity differences explain variations in call amplitude and duration, suggesting laryngeal control over airflow.
Area of Science:
- Primate vocalization
- Laryngeal electromyography
- Respiratory muscle physiology
Background:
- Understanding the neural and muscular basis of vocalization is crucial for studying animal communication.
- Macaque monkeys exhibit a range of vocalizations, but the precise muscle activation patterns remain incompletely understood.
Purpose of the Study:
- To investigate and describe the laryngeal and respiratory muscle activity during distinct macaque vocalizations (bark and coo).
- To correlate muscle activity with acoustic features such as amplitude and duration of vocalizations.
Main Methods:
- Electromyography (EMG) was used to record activity in key laryngeal (cricothyroid, thyroarytenoid, posterior cricoarytenoid) and respiratory (rectus abdominis, intercostals, diaphragm) muscles.
- Muscle activity was measured during spontaneous bark and coo vocalizations in macaque monkeys.
Main Results:
- Bark vocalizations showed activity in cricothyroid, thyroarytenoid, rectus abdominis, and intercostals, with quiet posterior cricoarytenoid and diaphragm.
- Coo vocalizations involved active cricothyroid, thyroarytenoid, intercostals, rectus abdominis, and diaphragm; posterior cricoarytenoid activity varied between individuals.
- Laryngeal muscle activity correlated significantly with the amplitude and duration of the coo call.
Conclusions:
- Vocalization differences (amplitude, duration) in macaques are primarily modulated by laryngeal modification of airflow.
- Variations in posterior cricoarytenoid muscle activity may contribute to differences in vocalization intensity.