Patterns of Laryngeal Electromyography and the Activity of the Respiratory System During Spontaneous Laughter

• Published in: Journal of neurophysiology Vol. 96; no. 1; pp. 442 - 450
• Main Authors: Luschei, Erich S, Ramig, Lorraine O, Finnegan, Eileen M, Baker, Kristen K, Smith, Marshall E
• Format: Journal Article
• Language: English
• Published: United States Am Phys Soc 01.07.2006
• Subjects: Action Potentials - physiology; Adult; Aged; Electromyography; Female; Humans; Laryngeal Muscles - innervation; Laryngeal Muscles - physiology; Laryngeal Nerves - physiology; Laughter - physiology; Male; Motor Activity - physiology; Periaqueductal Gray - physiology; Respiratory Physiological Phenomena; Respiratory System - innervation; Trachea - physiology
• ISSN: 0022-3077; 1522-1598
• DOI: 10.1152/jn.00102.2006

1 Department of Speech Pathology and Audiology, University of Iowa, Iowa City, Iowa; 2 Department of Speech, Language, Hearing Science, University of Colorado, Boulder, and 3 National Center for Voice and Speech, Denver Center for the Performing Arts, Denver, Colorado; and 4 Division of Otolaryngology/Head and Neck Surgery, University of Utah School of Medicine, Salt Lake City, Utah Submitted 31 January 2006; accepted in final form 18 April 2006 Laryngeal muscle electromyography (EMG) and measures of the behavior of the respiratory system have been made during spontaneous laughter in two groups of subjects. The smaller group also had a direct measure of tracheal pressure during this behavior. Laryngeal adductors such as the thyroarytenoid (TA) and lateral cricoarytenoid (LCA) exhibited brief high-amplitude bursts of activity, at a rate of approximately 5 Hz, which were usually associated on a 1 : 1 basis with the sound bursts (ha ha ha) of laughter. The laryngeal abductor, posterior cricoarytenoid (PCA), also showed bursts of activity that were out of phase with TA and LCA. The cricothyroid (CT) was only weakly, if at all, modulated during the bursting activity of the other laryngeal muscles. Tracheal pressure usually exhibited positive pressure pulses during laughter that were often, but not always, temporally correlated to the bursts of laryngeal adductor EMG activity. Such pressure modulations appeared to precisely determine when—and if—phonation was produced during the laugh. During laughter, laryngeal EMG is highly stereotyped both within and between subjects. In most instances, this activity appears to be supported by coordinated pulses of tracheal pressure. The periaqueductal gray (PAG) has been shown in animal studies to produce emotionally indicative vocalizations, in which the laryngeal and respiratory system are coordinated. Therefore, it is suggested that the PAG is involved with the production of laughter. Address for reprint requests and other correspondence: E. S. Luschei, 5901 Tolt River Rd. N.E., Carnation, WA 98014 (E-mail erichluschei{at}0040comcast.net )