EEG signatures of meditation proficiency among long-term meditators: An exploratory study

Novelty & Relevance of the study

Neural basis of meditative practices have interested many and studied extensively. Changes in neuronal signals during meditation has been widely studied. However, temporal consistency of these changes in neuronal signal has never been studied. For example, earlier studies have shown several EEG changes (in different modalities like spontaneous EEG oscillations, event related potentials, connectivity measures, etc.) among meditators compared to non-meditative controls. However, replicability of meditative mental state in the same subject on repeated occasions is yet to be explored. Replicability (temporal consistency) of electrophysiological signals (like EEG oscillatory changes) intentionally induced during meditation can be a neuro-marker for proficiency level of meditators. Such proficiency related neuro-markers can serve as reference gauge for the novice practitioners to improve their contemplative practices and the ensuing wellbeing effects. Hence, this study aims to assess replicability of mental state in EEG assessed brain oscillations during repeated meditation task performed by long-term meditation practitioners using EEG power spectrum based analysis strategies. Further, long-term meditation practice is expected to enhance overall health & reflect the same in well-being.  And also neurological health has connections to cardiac health and the bi-directional influence of heart and brain on each other has a vital role in physiological, psychological and social health and thus overall well-being. HRV being a significant marker of cardiac health and autonomic functioning and not studied in RY meditators exclusively till date holds to be a potential measure of study. In addition, various meditation techniques including RY meditation has shown to improve various indices of well-being in independent studies but indexing its correlation with EEG measures and HRV in long-term meditators has not been assessed. Thus, this study also aims to assess HRV and well-being scores and their correlation with EEG measures in long-term meditators. Thus apart from identifying neuro-marker for meditation proficiency, addition of these measures can help in eliciting the translational value of proficiency in meditation in terms of autonomic functioning and well-being, adding to the novelty of the study. 

Study design

The study comprises of single arm with repeated cross-sectional design. Long-term Rajayoga meditators (with 7 or more years of experience in practicing meditation) will be recruited as per the inclusion exclusion criteria. After recruitment subjects will be called on two consecutive days. For data acquisition they will be instructed to sit comfortably on a chair with armrest and EEG will be acquired from each subject for three conditions – Meditation (M), Working memory (W) and Rest (R). Data for these three conditions will be acquired in the following order on two consecutive days: R-M-R—W—R-M-R (R

• 4x4min; M - 2x15min; W - 1x15 min). 64-channel actichamp plus amplifier and brain recorder 1.23 (Brain Products, Germany) with an active electrode cap following 10/10 international system will be used for recording the data. Although primary aim of the study is to identify EEG signature for meditation related consistency in long-term meditators, subjects will also undergo rest and a cognitive task condition. Rest will be carried out in order to capture the baseline difference and cognitive task (W) being an objective task can act as a good comparator to measure consistency.

Apart from EEG, lead-I ECG data will be collected by connecting one electrode on left arm and the second electrode on right arm. The number of heartbeats will be obtained using standard algorithm and the RR intervals will be used to derive HRV measures. The ECG data will be collected simultaneously with EEG.

In addition, well-being related behavioral measures will be assessed through questionnaires assessing Happiness index, Equanimity and WHO Well-being index.

Expected outcomes and implications of the study

The study findings will help in identifying whether long-term meditators can achieve consistent mental states during repeated meditation tasks. Also, this may lead to identification of an EEG based neuro-marker for meditation proficiency. Combined with other bio-signals and related behavioral measures, benchmark target could be developed for objective assessment of progress in meditation training across schools and can also be used to assess neural engagement in novice meditators.