Sound presentation during different respiration phases alters the sound-induced vasoconstriction mediated by the sympathetic nerve.

The sympathetic orienting response induced by sound has been widely studied and utilized as an index of sound-induced emotions and other mental phenomena. Since sympathetic activity has its own oscillation that is synchronized with the respiration rhythm (sympatho-respiratory coupling), it is possible that the sound-induced orienting response of sympathetic activity varies depending on the respiration phase. In this study, the sound presentations were timed to coincide with the onset of inspiration or expiration. 10 experimental sounds were presented to 12 males aged 21-35 years. Respiration was monitored with an elastic chest band. Vasoconstriction at a finger was measured with laser Doppler flowmetry as a sympathetic orienting response. We found that the sound-induced vasoconstriction was larger for sounds presented in the inspiration phase than for those presented in the expiration phase, suggesting that the respiration network-derived sympathetic tone works as a gate for the sound-induced sympathetic tone.