Peripheral Arterial Stiffness Response to Heptanal Odor and its Relation to Subjective Evaluation

Odors induce various emotions, which in turn evoke responses in the autonomic nervous system. Therefore, attempts have been made to estimate the subjective evaluation of odors using autonomic activity. This study focuses on peripheral arterial stiffness, which is innervated by the vasoconstrictor activity of the skin sympathetic nerves, and aims to evaluate its relationship with subjective evaluation of unpleasant odors. To this end, an experiment was conducted to measure physiological signals and subjective evaluations by presenting participants with odorless air, and low and high concentrations of heptanal (N = 20). We then calculate the low- to high-frequency ratio of the heart rate variability and heart rate as indices of cardiac autonomic activity and the mean and variance of peripheral arterial stiffness as the vasoconstrictor activity of the skin sympathetic nerve indices. Analysis using a mixed linear model found a significant fixed effect of a positive slope (p < 0.01) for the variance of the peripheral arterial stiffness relative to the first principal component of the subjective evaluation interpreted as an unpleasant and high-arousal state. Previously, we reported that the maximum mean peripheral arterial stiffness during the stimulus interval correlates with subjective ratings of pleasantness and unpleasantness. The findings of this study suggest that peripheral arterial stiffness can be a predictor for the subjective evaluation of an odor.