Short-Term Meditation Training Alters Brain Activity and Sympathetic Responses at Rest, but not during the meditation

Abstract

Numerous studies have shown that meditation has a number of positive effects on the physical and psychological well-being of practitioners. As a result, meditation has become widely practiced not only as a religious practice but also as a self-regulation technique to achieve specific measurable goals. This raises the question of how quickly physiological changes can be noticed in individuals for whom meditation is not the main focus of their lives but rather a wellbeing keeping technique. Another question is whether it is possible to observe changes occurring directly during meditation and use bio- or neuro-feedback to enhance such meditation training and achieve tangible results. In our study, the experimental group of individuals with no previous meditation experience underwent eight weeks of training in Taoist meditation (2 sessions lasting 1 hour each week), under the guidance of a certified instructor. Participants in the control group attended offline group meetings during the same period, where they listened to audio books. All participants performed meditation testing before and after the intervention, following audio instructions. During the meditation practice, participants EEG, photoplethysmogram, respiratory rate, and skin conductance were recorded. The meditation training, but not the control group activity, resulted in topically organized changes of the resting state brain activity and heart rate variability. Specifically, we observed an increase in EEG power in multiple frequency bands (delta, theta, alpha, beta) and changes in the heart rate variability indicators associated with sympathetic system activation. However, no significant changes were observed when we compared the physiological indicators during the actual meditation process performed prior and post the 8-week training. We interpret these changes as signs of increased alertness and possibly accelerated resting metabolic rate. Importantly, these changes were observed after only 16 hours of meditation training performed during the 8-week period of time. The absence of difference in the band-specific power profiles between the experimental and control groups during the process of meditation conceptually complicates the development of assistive devices aimed at "guiding" the novice meditators during the actual meditation. Our results suggest that the focus in creating such digital assistants should rather be shifted towards monitoring neurophysiological activity during the time intervals outside of the actual meditation. The apparent changes occur not only in the EEG derived parameters but are also detectable based on the markers of autonomous nervous system activity that can be readily registered with a range of wearable gadgets which renders hope for a rapid translation of our results into practical applications.