Autonomic effects of music in health and Crohn's disease:the impact of isochronicity, emotional valence, and tempo

BACKGROUND: Music can evoke strong emotions and thus elicit significant autonomic nervous system (ANS) responses. However, previous studies investigating music-evoked ANS effects produced inconsistent results. In particular, it is not clear (a) whether simply a musical tactus (without common emotional components of music) is sufficient to elicit ANS effects; (b) whether changes in the tempo of a musical piece contribute to the ANS effects; (c) whether emotional valence of music influences ANS effects; and (d) whether music-elicited ANS effects are comparable in healthy subjects and patients with Crohn´s disease (CD, an inflammatory bowel disease suspected to be associated with autonomic dysfunction). METHODS: To address these issues, three experiments were conducted, with a total of n = 138 healthy subjects and n = 19 CD patients. Heart rate (HR), heart rate variability (HRV), and electrodermal activity (EDA) were recorded while participants listened to joyful pleasant music, isochronous tones, and unpleasant control stimuli. RESULTS: Compared to silence, both pleasant music and unpleasant control stimuli elicited an increase in HR and a decrease in a variety of HRV parameters. Surprisingly, similar ANS effects were elicited by isochronous tones (i.e., simply by a tactus). ANS effects did not differ between pleasant and unpleasant stimuli, and different tempi of the music did not entrain ANS activity. Finally, music-evoked ANS effects did not differ between healthy individuals and CD patients. CONCLUSIONS: The isochronous pulse of music (i.e., the tactus) is a major factor of music-evoked ANS effects. These ANS effects are characterized by increased sympathetic activity. The emotional valence of a musical piece contributes surprisingly little to the ANS activity changes evoked by that piece

Heart rate variability results of Experiment 3.

<p>The acoustic stimuli decreased all heart rate variability parameters compared to silence except the LF/HF ratio, thus reproducing the results of Experiment 1 and 2. Note the generally similar results of healthy subjects and Crohn′s disease patients. This demonstrates that Crohn′s disease is not per se characterized by a different autonomic tone or autonomic reactivity. <i>Lg</i>: indicates logarithmized data where transformation was applied; <i>Pleasant</i>: pleasant music; <i>Unpleasant</i>: music-like noise; *: <i>p</i> < .05; **: <i>p</i> < .01; ***: <i>p</i> < .001. For description of HRV parameters see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0126224#pone.0126224.t001" target="_blank">Table 1</a>.</p

Characteristics of participants in Experiment 3.

<p>Characteristics of participants in Experiment 3.</p

Summary of heart rate and heart rate variability effects of pleasant music compared to silence.

<p>Summary of heart rate and heart rate variability effects of pleasant music compared to silence.</p

Stimuli and procedure of Experiment 1.

<p>A, B, and C show 30 second samples of a triplet of corresponding acoustic stimuli used. Notice that the isochronous tones in B and C have identical tempi as the stimulus in A. D demonstrates the sequence of one trial. Twenty-five such trials with different stimuli were presented. Before and after each auditory stimulus, short sinus tone sequences (indicated by the two notes in the figure) were used to notify the subjects that a trial will start, respectively the rating procedure will follow.</p

Summary of heart rate and heart rate variability effects of isochronous tones, music-like noise, and unpleasant music compared to silence.

<p>Summary of heart rate and heart rate variability effects of isochronous tones, music-like noise, and unpleasant music compared to silence.</p

Parameters of heart rate variability (HRV).

<p>Parameters of heart rate variability (HRV).</p

Clinical characteristics of Crohn′s disease patients of Experiment 3.

<p>Clinical characteristics of Crohn′s disease patients of Experiment 3.</p