EEG Derived Neuronal Dynamics during Meditation: Progress and Challenges

Table 1

Meditation induced changes in EEG brainwaves.

Author	Meditation style	Subjects	Signal processing	Results
Sobolewski et al. [12]	Buddhist	26	—	↑ ERP
Chang and Lo [13]	Zen	41	Wavelet	Alpha suppression (though more alpha than nonmeditators)
Huang and Lo [14]	Zen	23	—	↑ frontal alpha and occipital beta
Kubota et al. [16]	So-Soku	25	Spectral analysis	↑ FmTheta (reflecting continuous attention)
Lo and Zhu [17]	CHAN	16	Wavelet decomposition and Mahalanobis fuzzy C-means	Time period of frontal alpha more than occipital alpha (reflecting calm mind)
Lo and Chang [18]	CHAN and Chakra focusing	20	Continuous Time Wavelet Transform	Higher lateral interaction of dominant alpha epochs in right and left temporal regions (reflecting more inward attention)
Berkovich-Ohana et al. [23]	MM	12	Spectral analysis	(i) State effect: ↑ prefrontal gamma; (ii) Trait effect: ↓ gamma over frontal and midline areas
Cahn et al. [24]	MM	16	ICA	(i) ↓ frontal alpha; (ii) ↑ frontal theta and gamma (reflecting better synchronized function)
Ahani et al. [25]	MMI	34	Spectral, phase analysis	(i) ↑ frontal theta (enhancement of attentional and working memory process); (ii) Minor ↑ in right temporal and occipital alpha; (iii) ↑ beta and EEG synchrony
Xue et al. [26]	IBMT	45	Network analysis	↑ FmTheta
Chan et al. [27]	TBRT	19	FFT	(i) ↑ alpha asymmetry index (measure of positive emotions); (ii) ↑ FmTheta
Warrenburg et al. [28]	PR and TM	6	—	Rare theta activity (5–7 Hz)
Travis [30]	TM and TM-Sidhi	26	Spectral analysis and coherence analysis	During TM-Sidhi; (i) ↑ frontal alpha1 and beta1; (ii) No change in coherence
Newande and Reisman [33]	TM (individual and group study)	10	Time frequency analysis	Individual study; (1) Open eyes; (i) Strong coherence in delta and theta; (ii) ↓ alpha coherence; (2) Closed eyes; slight delta, almost no theta, and significant alpha coherence; (3) Experienced meditators reflect strong alpha coherence and shift to theta coherence
				Group meditation; (1) Open eyes; ↑ alpha being strongest, slight more delta and theta coherence than individual study; (2) Closed eyes; (i) ↑ alpha coherence and theta coherence; (ii) ↓ delta activity
Hebert et al. [34]	TM	27	Time domain method	↑ alpha synchrony
Eskandari and Erfanian [35]	TM	10	Wavelet decomposition	(i) Alpha ERS and beta ERS during imagination of hand movement; (ii) Alpha ERD during rest
Kjaer et al. [36]	Yoga Nidra meditation	8	Spectral analysis	(i) ↑ theta power; (ii) ↓ alpha power
Aftanas and Golocheikine [37]	Sahaja Yoga	20	Nonlinear system theory: DCx	(i) ↑ theta1, theta2, and alpha1 powers; (ii) ↓ beta3 (signifies problem solving and thinking)
Aftanas and Golocheikine [38]	Sahaja Yoga	58	FFT	(i) Long-Term Meditators: ↑ theta and alpha1 power; (ii) Short-Term Meditators: alpha2 desynchronization
Baijal and Srinivasan [39]	Sahaja Samadhi	20	Spectral and coherence analysis	(i) ↑ frontal theta during deep meditation; (ii) ↑ theta coherence; (iii) ↓ theta in parietal
Arambula et al. [40]	Kundalini	1	Spectral analysis	↑ alpha on entering meditation
Elson et al. [44]	Ananda Marga	11	—	(i) ↑ theta; (ii) Stable alpha-theta band
Ghista et al. [42]	Ananda Marga	4	—	↑ alpha
Khare and Nigam [43]	Ananda Marga	30	Spectral analysis	↑ alpha and beta
Y.-J. Park and Y.-B. Park [45]	PB	58	FFT	(i) ↑ alpha1; (ii) ↓ theta
Tsai et al. [46]	Advanced breathing	1	Single time series analysis	↑ bilateral alpha and theta
Lehmann et al. [47]	Tibetan Buddhists, QiGong, Sahaja Yoga, Ananda Marga, and Zen	13; 15; 14; 14; 15	Lagged intracortical coherence	Lowered interdependence between different functions as shown by delta and beta2 band activities
Barnhofer et al. [49]	Mindfulness breathing and loving kindness	8; 7	FFT	Strong left prefrontal activation (reflects strong tendency for motivation and positivity)
Vialatte et al. [58]	Bhramari Pranayama	8	Complex Morlet wavelets and Fourier analysis	↑ frequencies in beta (15–35) and gamma (>35) and increased theta activity

1: stability towards negative stimuli, 2: more internalized attention, 3: open monitoring, 4: improved functional integration, 5: due to awake, alert, and open eyes, and 6: relaxed and deeper level of meditation.