[Assessment of autonomic function by the spectral analysis of heart rate variability: an examination in a mirror...

The effect of an experimental task on autonomic function was investigated by spectral analysis of heart rate variability in 13 male college students. Power spectral density of heart rate variability has been said to contain two significant components: respiratory sinus arrhythmia (RSA) as an index of cardiac vagal activity, and Mayer wave related sinus arrhythmia (MWSA) as an index of sympathetic activity with vagal modulation. Those two components were examined during a task of mirror drawing on the CRT. In order to eliminate the effect of respiratory rate on RSA, the respiratory rate was controlled at 15 breaths/min. Furthermore, the coefficient of variance of R-R interval (CV-RR) and the fluctuation of plethysmograph (PTG) were calculated simultaneously. Results indicated that, while RSA decreased significantly, MWSA did not change during the task. On the other hand, neither CV-RR nor PTG showed any significant differences during the task. These findings indicated that cardiac parasympathetic activity was diminished in the mirror drawing task. The significance of spectral analysis of heart rate variability were discussed.