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EEG Power and Coherence in Zen Meditation
James V. Hardt, Ph.D.
Society for the Study of Neuronal Regulation conference, May 1-4, 1994
Zen philosophy seeks to bridge the inner and outer worlds,
neither denying nor rectifying either the inner or outer realities. Yoga
meditation is done eyes closed in most traditions, and the mind is fully
absorbed with inner events, to the exclusion of the outer world of the
senses. Yoga philosophy is more likely to deny or devalue external reality in
favor of the "real" or superior reality within. On the other hand, Zen is
typically done with the eyes half open, downcast, with soft focus (ie. blurred
or defocused vision). This visual strategy could help Zen bridge the gulf
between inner and outer worlds. The Zen acceptance of sensory input (even
distractions), and their integration into a steady inner awareness, would seem
more compatible with the sensory processing requirements of the EEG feedback
setting. Indeed, the requirement of the EEG trainee to open his or her eyes for
several seconds every 2 minutes to view the digital feedback scores may be more
compatible with Zen than with Yoga practice. It would therefore seem useful to
study the EEG changes in Zen mediation, to better understand the possibilities
of EEG feedback training.
Thirty Zen meditators rated "Beginner", "Intermediate", or
"Advanced" by their Roshi (Zen Master) sat for baselines and zazen meditation
while their EEGs were recorded from 6 sites (O1, O2, T3, T4, F3, F4 referred to
ipsilateral Centrals: C3 and C4). These EEGs were computer analyzed for power
spectrum (6 channels) and threshold coherence spectrum (8 channel pairs), and
were graphed as compressed spectral arrays. Beginners had low alpha and low
coherence confined posteriorly (O1, O2), if present at all. Intermediate
meditators showed increasing alpha amplitudes spreading anteriorly and slowing,
and coherence developing and spreading anteriorly. Advanced meditators showed
the highest alpha amplitudes, up to 100 microvolts in long spindles of 15-20
sec. with hypovariability of amplitude. Advanced meditators showed alpha
spreading anteriorly all the way to the Frontals, and slowing and spreading
across a wide frequency range, which extended down into the theta
range. Coherence in advanced meditators, like alpha activity, tended to be
present only during the meditation period, and some coherence patterns were
seen only during the deepest (mid) portion of the meditation period, as for
example: Frontal:Occipital coherence (F3:01), Temporal:Frontal (F3:T3 and
F4:T4), and the bilateral Frontal (F3:F4). Advanced meditators were more able
to turn their alpha amplitude and coherence on during, and off after, the
mediation period, whereas Intermediate meditators, if they were able to turn
either or both of these patterns on during mediation seemed either unable or
unwilling to turn them off when the meditation ended, so these patterns
persisted into to post-meditation baselines of Intermediate
meditators. Electrophysiological criteria confirm distinctions between
individuals rated as Beginner, Intermediate, or Advanced by their Roshi.
Four Zen EEG changes
- Control subjects show no alpha increases.
- Beginner Zen subjects show increased alpha amplitude mainly at the back of the head (Occipitals).
- Intermediate Zen subjects show increased alpha amplitudes which spread
forward on the head, and which slow in frequency.
- Advanced Zen subjects show the above changes, but in addition also show rhythmic trains of theta EEG,
which are morphologically different from the theta of drowsiness. The theta
wave criterion is a stringent one for alpha feedback, since only advanced Zen
with 21-40 years showed it.
Method (Equipment)
All EEG data were collected with Biocybernaut Institute
Mark 5A Hybrid Spectral Analysis systems, with 64 channel 12 bit A/D
converters. Input to the A/D was provided by 8 EEG amplifiers, each with 8
analog filters. The filters were very sharp (300-400 dB/octave roll off, and
1/3 dB ripple in the pass band). The filters provided delta, slow half of
theta, fast half of theta, slow third of alpha, broad band alpha, fast third of
alpha, slow half of beta, broad band beta signals on each of the 8 EEG
channels: bilateral Occipital, Central, Temporal, and Frontal (O1, O2, C3, C4,
T3, T4, F3, F4). The smoothed, full wave rectified filter output was input to
the A/Ds. Four channel feedback was provided simultaneously from broad band
alpha at the Occipital and Central sites (O1, O2, C3, C4), while the Temporal
and Frontal sites were only passively recorded (ie. no feedback). Recording was
monopolar to linked ears reference.
Method (Procedure)
Every effort was made to follow recommended procedures for
successful alpha enhancement training (Hardt, 1974, 1990). subjects had 7
consecutive days of alpha feedback training. Each day had eyes open, eyes
closed and white noise baselines. Alpha enhancement training times were 60
minutes on days 1-2, 90 minutes on days 3-4, and 120 minutes on days 5-7, with
the option given to trainees to do additional alpha enhancement on days
5-7. Alpha feedback was both audio tones and digital scores (visual). There
were 4 tones from 4 spatially separated speakers (from O1, O2, C3, C4), with
tone volume proportional to instantaneous amplitude of the alpha
envelope. Feedback tones operated for 2 minute intervals, then were interrupted
for 8 seconds of digital display of integrated amplitude alpha scores from each
of the 4 feedback sites. Then score displays turned off and tone feedback
resumed. After each session, an experienced trainer asked for subjective
reports and gave a review of results.
Results
Determination of Cumulative Change Scores and
t-testing: Sets of change scores were calculated, separately for
each of the 17 subjects, on each of the 7 days of training. Each set had 64
change scores (8 head sites with 8 filters at each head site).
Future alpha and theta studies may see benefits in design,
execution, interpretation, and application from greater understanding of Zen
philosophy, Zen practice, and the Zen progression of mind states from
Beginner's mind, through kensho, culminating in satori. Learning to
extend one's moments of peak performance (staying in the "Zone") through
properly designed programs of EEG feedback training is now a realistic
goal. Slightly more difficult, is the goal of learning how to enter the "Zone"
whenever peak performance is required. Attainment of these goals promises the
rewards of peak performance for athletics, business, science, education,
government, the arts, perhaps in every area of human endeavor where people are
in search of excellence.
References
Allman, W.F., The Mental Edge, Science & Society,
(In) U.S. News & World Report, 113(5), 50-56, August 3 (1992).
Anand, B.K., Chhina, G.S., & Singh, B., Some aspects of
electroencephalographic studies in Yogis, Electroencephalography and
Clinical Neurophysiology 13, 452 (1961).
Hardt, J.V. Alpha EEG responses of low and high anxiety
males to respiration and relaxation training and to auditory feedback of
occipital alpha. Dissertation Abstracts, International,
35(4), Catalog No. 74-19309, 1912B-1913B, (1974).
Hardt, J.V. and Kamiya, J. Anxiety change through EEG alpha
feedback: Seen only in high anxiety subjects. Science, 201,
79-81, (1978).
Hardt, J.V., Timmons, B.H., Yeager, C.L., & Kamiya,
J. Studying power and coherence relationships in 6-channel EEGs: A McLuhanistic
technique applied to Zen mediation, Proceedings of the Biofeedback Research
Society, 7, 31, Colorado Springs, February, (1976).
Hardt, J.V. EEG Biofeedback Method and System for Training
Voluntary Control of Human EEG Activity, United States Patent
#4,928,704, May 29, (1990).
Kasamatsu, A. & Hirai, T., An Electroencephalographic
study on the Zen meditation (zazen), Folia Psychiatrica et Neurologica
Japonica 20, 315-336 (1966).
Wenger, M.A. & Bagchi, B.K., Studies of autonomic
functions in practitioners of Yoga in India, Behavioral Science,
6, 312-323 (1961).
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