The fMRI procedure itself—lying in a noisy, confined tube—alters both subjective experience and brain activity during Transcendental Meditation (TM), potentially confounding results from fMRI studies of meditation. Twenty-three TM practitioners (11 short-term, averaging 2.2 years; 12 long-term, averaging 34.8 years) underwent eyes-closed rest and TM practice in three conditions: sitting upright, lying supine, and lying inside a simulated fMRI tube with 110 dB recordings. During the simulated fMRI condition, participants reported shallower meditation and greater agitation. Skin conductance decreased least in that condition. Frontal and parietal EEG power decreased from sitting to simulated fMRI in alpha2 through gamma bands. The default mode network was more active during TM when sitting compared to the simulated fMRI condition.
During Transcendental Meditation, two distinct phases—transcending and undirected mentation—show different patterns of brain electrical activity compared to ordinary rest. EEG microstate analysis of 20 TM practitioners revealed that resting and transcending both showed less prominence of Class A microstates and more prominence of Class D microstates than undirected mentation. Transcending also showed less prominence of Class C microstates than undirected mentation. These patterns suggest that during resting and transcending, there is increased reference to reality and decreased visualization, while transcending involves less saliency of internally generated thoughts, reflecting more detached and less evaluative processing. The cycling between these phases during TM may train flexible modulation of microstate parameters relevant to psychiatric disorders.
Listening to live Vedic recitation produces deeper inner experiences and distinct brain patterns compared to Transcendental Meditation (TM) practice. Thirty-seven subjects reported that Vedic recitation felt deeper, more internal, and characterized by lively silence. EEG recordings showed significantly higher theta2 and alpha1 coherence in frontal, parietal, and frontal-parietal regions during Vedic recitation than during TM. Theta2 coherence, associated with attending to internal mental processes, supports subjects' descriptions of the recitations as internal vibrations rather than external sounds. Higher alpha1 coherence, seen during pure consciousness experiences in TM, supports reports of greater depth during recitation.
Transcendental Meditation (TM) does not involve focused attention or voluntary control of mental content, even in beginners. Eighty-seven TM practitioners with one month to five years of experience reported similar levels of transcendental experiences regardless of practice duration, with a flat regression (r=.07). Brain activity measured by eLORETA showed theta and alpha activation in the default mode network during both eyes-closed rest and TM, and beta2 and beta3 activation in the central executive network during a task. TM uniquely showed higher theta orbitofrontal activation compared to rest. These findings indicate TM should not be categorized with Focused Attention meditations, which involve gamma EEG and default mode network deactivation.