Effects of Mental Task on Heart Rate Variability during Graded Head-Up Tilt.

Abstract

Abstract. In this study, we used spectral analysis of heart rate variability (HRV) to estimate the changes in autonomic control in response to disparate stimuli produced by mental task and graded head-up tilting. The low frequency (LF) component of HRV provided a quantitative index of the sympathetic and parasympathetic (vagal) activities controlling the heart rate (HR), while the high frequency (HF) component of HRV provided an index of the vagal tone. We studied 17 healthy male subjects (21-25 yr of age) who were placed on a tilt-table and the graded tilt-protocol involved tilted sine angles 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0. These tilt-protocols were repeated with or without the mental task, which consisted of auditory distinctive reactiontime tasks. The basal autonomic mode against the graded head-up tilt was characterized by reciprocal changes in sympathetic and vagal tones. There were significant increases of HR corresponding to the mental task with lower tilt-angle, albeit the changes with higher tilt angles were not significant. Furthermore, there were increases and decreases of the LF component induced by the mental task at lower and higher tilt-angles, respectively. These results revealed that the different responses of HR and LF component against the same tasks could be derived from the alterations of autonomic mode during gradual changes in autonomic control.

Thermoregulatory Effect in Humans of Suppressed Endogenous Melatonin by Pre-Sleep Bright-Light Exposure in a Cold Environment

“…LF is often interpreted as an index influenced by both sympathetic and parasympathetic activity. However, it has been reported that the LF response could vary according to different postures from the supine to the upright position (Ishibashi et al, 1999). One of the most frequently cited papers on HRV (Pomeranz et al, 1985) points out that the vagal blockade by intravenous administration of atropine in a supine subject is also capable of reducing LF by 84%; it was concluded that in this posture, the LF is mediated entirely by the parasympathetic system.…”

Specific Physiological Responses in Women with Severe Primary Dysmenorrhea during the Menstrual Cycle

“…From the ECG monitoring, heart rate (HR) and heart rate variability (HRV) were derived. Many studies have reported the reliability of HRV as a noninvasive index of ANS activity (Ishibashi et al, 1999;Miyatsuji et al, 2002). The high frequencies (HF) of HRV relate to parasympathetic activity, while the low frequencies (LF) of HRV are associated with both parasympathetic and sympathetic activities (Pomeranz et al, 1985).…”

Measurement of visual fat igue for large-sized TVs in a home viewing environment

“…Measured items: The following items, verified by the prior study [5][6], were adopted: (1)subjective assessment of fatigue (SAF) through questionnaires (provided by the Japan Society for Occupational Health) and interviews, (2)blinking rate,(3) amplitude rates of differential calculus wave patterns for blinking,(4)heart rate variability (level of sympathetic nerve activity: LF/HF (LF/HF is defined by the ratio of the low frequency band (LF: 0.04-0.15 Hz) and the high frequency band (HF: 0.15-0.5 Hz), calculated by employing FFT analysis using the R-R interval based on heart rate variability obtained from the electrocardiogram [7] [8]), and (5) task performance(rates of correct answers. )…”