Provided by Cognitive Sciences ePrint Archive
AMPLITUDE OF HEART RATE MODULATION WITH THE PERIOD OF
3 CARDIOCYCLES DEPENDS ON THE PHYSIOLOGICAL AROUSAL OF THE
BRAIN
V. Mukhin
Institute of Experimental Medicine, St. Petersburg, Russia
e-mail: [email protected]
Introduction. Last conference we suggested that there is the modulation with a period of
3 cardiocycles in heart rate variability and that its amplitude is associated with mental status. The
aim of this study was to specify a component of psychophysiological status this amplitude is
associated with. We hypothesized that this component is the physiological arousal of brain.
Arousal is a general activation of the brain cortex by the reticular activating system.
Methods. It is known that mental relaxation, meditation and sleeping associated with
reduction of the arousal level. Therefore, we use these states to prove our hypothesis. In
according to these states the study was designed in 3 stages. Short tachograms of 300
cardiointervals recorded in different psychophysiological states was analyzed with the discrete
Fourier transform. Some of the tachograms were got of the PhysioNet that is an Internet
physiological signals database funded by the National Institutes of Health. This database is
available via the URL http://www.physionet.org/physiobank/database/meditation/.
Results and discussion. Stage one. In group of 12 volunteers ECG was recorded
subsequently in rest and during mental relaxation. To provoke mental relaxation they were
introductory asked to imagine some pleasant and relaxing things from their experience while
staying in rest. The amplitude of the modulation with the period of 3 cardiocycles decreases in
10 volunteers during relaxation that was statistically significant (p≤0,05).
Stage two. In the other group of 12 subjects heart rate was analyzed at rest and during
Kundalini Yoga (8 subjects) and Chi (4 subjects) meditation (the data from the PhysioNet
database). The amplitude of the modulation with the period of 3 cardiocycles decreases in 11
subjects during meditation and it was also statistically significant (p≤0,01).
Stage three. The spectral analysis of heart rate was carried out in group of 11 subjects
during sleeping (the data from the PhysioNet database). The average level of the 3-cardiocycle
modulation in this group was significantly lower than one in the group of 38 sleepless rest
subjects (p≤0,02) but not than one in the group of 11 meditators during meditation.
In conclusion. The results showed that the amplitude of 3-cardiocycle modulation of
heart rate in records of 300 cardiointervals depends of the physiological arousal of brain. As
arousal is a physiological component of stress, the amplitude of this heart rate modulation may
be used as a diagnostic parameter on the arousal in stress related studies.