Effect of voluntary EEG α power increase training on heart rate variability

The following objectives were set out to study the effect of EEG α power increase training on the heart rate variability (HRV) as an index of the autonomic regulation of cognitive functions: (1) to establish the interrelation between a voluntary increase in the α power in the individual upper α band and the HRV and related characteristics of cognitive and emotional spheres; (2) to determine the nature of the relationship between the α-activity indices and HRV depending on the resting α-frequency EEG pattern; and (3) to study how the individual α-frequency EEG pattern is reflected in the HRV changes as a result of biofeedback training. Psychometric indices of cognitive performance and the characteristics of EEG α activity and HRV were recorded in 27 healthy men 18-34 years of age before, during, and after ten training sessions of a voluntary increase in α power in the individual upper α band with the eyes closed. To determine the biofeedback effect in the α power increase training, the data of two groups were compared: the experimental, with a real biofeedback (14 subjects), and the control, with a sham biofeedback (13 subjects). The follow-up effect of the training was assessed one month after its end. The results showed that α biofeedback training increased the resting α frequency, improved cognitive performance, reduced psychoemotional stress, and increased HRV only in the subjects with a low baseline α frequency. In the subjects with a high baseline resting α frequency, the α biofeedback training had no effect on the resting α power and cognitive performance but reduced the HRV (judging by the pNN50 parameter). The positive correlation between the α peak frequency and HRV in subjects with initially low α frequency and the negative correlation in the subjects with a high baseline α frequency explains the opposite biofeedback effects on HRV in subjects with low and high α frequency. From the theoretical standpoint, the results of this study contribute to understanding the mechanisms of heart-brain neurovisceral relationships and their effect on the cognitive performance. From the applied standpoint, they suggest that EEG biofeedback can be used for improving autonomic regulation in healthy subjects and the development of individual approaches to the development of the biofeedback technology, which can be used both in clinical practice for treatment and rehabilitation of psychosomatic syndromes and in educational training. © 2013 Pleiades Publishing, Ltd.