The effects of musical tempo and non-invasive neuromodulation on autonomic control of the heart

Music is viewed as conferring health benefits, with tempo being the most influential parameter for altering human physiology and psychology. However, this work has used stimuli that manipulate multiple musical parameters at a time. Therefore, this thesis investigated the effects of musical tempo manipulations on cardiovascular autonomic function and subjective responses. Tempo manipulations comprised of stepped (sudden) increases and decreases in the speed of a simple beat pattern and heart rate variability estimated autonomic balance. Shifts towards parasympathetic predominance occurred for the stepped decrease in tempo stimulus but not for the stepped increase in tempo. When using more musically sophisticated stimuli, greatest vagal tone occurred for the slowest tempo (60bpm) of the stepped decrease in tempo stimulus. Autonomic function did not differ between an experimental (melody and rhythm) and control group (rhythm only). However, the latter experienced greater subjective arousal than the former. Growing interest in wearable technologies led to the testing of a wearable device that combined relaxation music with transcutaneous vagal nerve stimulation (tVNS). tVNS is a non-invasive neuromodulatory technique that administers small electrical impulses to the outer ear to stimulate the auricular vagus nerve. Both stimuli individually promote shifts towards parasympathetic predominance. It was anticipated that music combined with tVNS would elicit the greatest shifts towards parasympathetic predominance. However, the sham was equally as effective as music only, tVNS only, and their combination at altering autonomic activity. Autonomic responses to all stimuli employed in the thesis were predicted by baseline LF%. These findings suggest that music and wearables may be susceptible to placebo effects