H. Kimata, A. Morita, S. Furuhata
Jan 1, 2009
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Influential Citations
9
Citations
Quality indicators
Journal
European Journal of Clinical Investigation
Abstract
Sir, We previously reported that laughter (1) reduced allergic responses in patients with atopic dermatitis [1] and (2) improved allergen-induced bronchial responsiveness in patients with bronchial asthma [2]. The healthy effects of laughter have been supported by a lot of anecdotal reports and several quantitative studies. But difficulty in accurately measuring laughter has previously hindered detailed investigations. It is a pressing issue to improve the method of assessing laughter. In previous studies, measuring laughter by pharyngeal or laryngeal electromyography (EMG) [3,4] was attempted, but it required many apparatuses and special techniques [5]. Although measuring laughter by abdominal muscle EMG was a relatively easy method, it was usually mixed with electrocardiogram (ECG) measurements [6], and moreover, they were not primarily involved in laughter. More suitable muscles should be specified to measure EMG. In this study, a new methodology with diaphragm lectromyogram (EMG) is advocated, and method and utility are discussed in detail. Six university students (three male and three female, age range 21–34 years) were recruited into the study after obtaining their informed consent. All of the subjects were healthy and they did not take any medication at the time of the study. Patterns of EMG wwere measured while they were sitting and viewing several Japanese comic videos. Disk electrodes were applied to just on and 3 cm below the xiphoid process of the subjects. We first identified ECG readings (Fig. 1a), and we observed that laughter elicited a peculiar bursting pattern of EMG (Fig. 1b). Hearty laughter elicited bigger waves. Bursting patterns of EMG split into several divisions, when laughter was associated with a special respiratory pattern designated as ‘ha, ha, ha’ (data not shown). Although the size and duration varied, the waving patterns of laughter-elicited EMG were clearly different from patterns of EMG elicited by coughing (data not shown) or sneezing (Fig. 1c). To our knowledge, measuring diaphragm EMG as described here is the first exact system for the measurement of laughter itself. Since this measuring system can specify the starting point and duration of laughter precisely of 1/3000, it will make detailed analysis of the healthy effects of laughter possible. Furthermore, this system must contribute to development in many fields including sociology, psychology and medical science because this method does not require any special medical or mechanical techniques. Collectively, the measuring system of laughter by diaphragm EMG is suitable as a precise way to assess laughter, and is recommended for its advantages of simplicity and convenience. Similar and more detailed studies in a wide age group will be needed.