Intern. J. Neuroscience, 116:1519–1538, 2006
Copyright C ?2006 Informa Healthcare
ISSN: 0020-7454 / 1543-5245 online
CROSS-SECTIONAL AND LONGITUDINAL STUDY
OF EFFECTS OF TRANSCENDENTAL MEDITATION
PRACTICE ON INTERHEMISPHERIC FRONTAL
ASYMMETRY AND FRONTAL COHERENCE
Brain Consciousness and Cognition Lab
Maharishi University of Management
Fairfield, Iowa, USA
Brain Research Institute
Maharishi University of Management
Fairfield, Iowa, USA
Two studies investigated frontal alpha lateral asymmetry and frontal inter-
hemispheric coherence during eyes-closed rest, Transcendental Meditation (TM)
practice, and computerized reaction-time tasks. In the first study, frontal coherence
and lateralized asymmetry were higher in 13 TM subjects than in 12 controls.
In the second study (N = 14), a one-year longitudinal study, lateral asymmetry
did not change in any condition. In contrast, frontal coherence increased linearly
during computer tasks and eyes-closed rest, and as a step-function during TM
practice—rising to a high level after 2-months TM practice. Coherence was more
sensitive than lateral asymmetry to effects of TM practice on brain functioning.
Key words: coherence, consciousness, frontal lobes, lateral asymmetry, medita-
tion, Transcendental Meditation
Received 24 June 2005.
Maharishi University of Management, 1000 North Fourth Street, FM 1001, Fairfield, IA 52557,
USA. E-mail: email@example.com
1520 F. TRAVIS AND A. ARENANDER
The frontal cortex is considered the top of a hierarchy of neural structures
that integrate external information and internal states for the representation,
temporal organization, and execution of complex mental and behavioral
responses to environmental challenges (Case, 1992; Fuster, 1999). The frontal
cortex is reciprocally connected with nearly all other cortices, with subcortical
neural connectivity supports the role of frontal circuits with attention, learning,
planning working memory, language, judgment, moral reasoning, emotions,
and self-concept (Ben Shalom, 2000; Davidson & Irwin, 1999; Grady, 1999;
Kelley et al., 2002; Vogeley et al., 1999).
Two electrophysiological measures have been used to characterize frontal
lobe functioning. One is a measure of interhemispheric power differences,
called “lateral asymmetry”; the other a measure of functioning connectivity,
called “coherence.” These measures have been used to quantify immediate and
long-term effects of meditation practices on brain functioning.
Frontal alpha lateral asymmetry patterns distinguish cognitive task perfor-
mance andaffective states.Duringpredominately verbal tasks,decreased alpha
power is reported in the left hemisphere suggesting increased left-hemisphere
activation in verbal tasks (Davidson et al., 1990; Tomarken et al., 1990). A
disposition toward positive and negative affect has also been characterized
by lateral asymmetry patterns (Tomarken et al., 1992). Specifically, positive
emotion and, more generally, approach-orienting disposition/behavior toward
rewarding stimuli is associated with increased activation in left hemispheric
dorsolateral and ventral medial prefrontal cortices, as well as in the left
amygdala. In contrast, right prefrontal cortex activation has been observed
during certain forms of negative emotion and during withdrawal-oriented
disposition/behavior away from aversive stimuli (Davidson, 2002; Davidson
et al., 2000a, 2003a).
Recent research reports effects of Mindfulness-Based Stress Reduction
(MSBR) program on frontal alpha lateral asymmetry (Davidson et al.,
2003b). EEG was recorded in subjects randomly assigned to an 8-week
Mindfulness-Based Stress Reduction or to no treatment control during rest
and during negative and positive mood induction conditions at baseline, 8
weeks, and 4 months. Mindfulness meditation resulted in significant left-
lateralized asymmetry only in central leads, which are predominately over
motor cortex (Homan et al., 1987), and there was a trend for significant left-
lateralized asymmetry in temporal leads. No significant effects of Mindfulness
& Arenander, 2004a), the cortical area most consistently associated with
FRONTAL ASYMMETRY, COHERENCE, AND TM PRACTICE1521
suggest possible influences of meditation practice on EEG interhemispheric
EEG coherence is a second marker of frontal functioning. Coherence
quantifies the phase consistency between pairs of signals in specific frequency
bands (Nunez et al., 2001; Thatcher, 1992). Coherence is considered a
measure of functional brain connectivity necessary for network formation and
with white matter lesions and decreased cerebral blood flow (Leuchter et al.,
normal aging (Kayama et al., 1997). Higher levels of coherence are associated
with normal maturation (Thatcher et al., 1986), information exchange (Petsche
et al., 1997; Pfurtscheller & Andrew, 1999), and functional co-ordination
(Gevins et al., 1989) between brain regions.
decades, reports that frontal (F3-F4) EEG coherence (1) is higher during TM
practice compared to eyes-closed rest (Dillbeck & Bronson, 1981; Dillbeck
et al., 1981; Levine, 1976; Orme-Johnson & Haynes, 1981; Travis et al., 2002);
(2) rises to high levels in the first minute of TM practice and continues at
these high levels throughout the practice (Travis & Wallace, 1999); and (3)
is higher during eyes-open tasks in subjects with more years TM practice
(Levine, 1976; Travis et al., 2002). Although early research on effects of TM
practice investigated narrow EEG bands (theta and alpha) during TM practice,
more recent research suggests that broadband coherence better characterizes
Transcendental Meditation practice (Travis et al., 2002).
practice, a cross-sectional and longitudinal study was conducted of effects of
Transcendental Meditation practice on frontal lateral asymmetry and frontal
literature, Davidson’s protocol for recording and calculating alpha lateral
asymmetry during eyes-closed rest from frontal leads was followed (Davidson
et al., 2003b). To facilitate comparison with the TM literature, the authors
recorded and calculated broadband frontal EEG coherence during tasks (Travis
et al., 2002). The studies reported here focused on these specific measures that
1TM and Transcendental Meditation are registered trademarks licensed to Maharishi Vedic
Education Development Corporation and are used with permission.
1522 F. TRAVIS AND A. ARENANDER
have been reported in the literature. Future research can expand the measures
taken and test brain patterns in different meditating populations.
This study addressed three research questions: (1) How do eyes-closed
frontal alpha resting asymmetry and frontal broadband EEG coherence differ
correlations of these two brain measures with five measures of psychological
and personality traits? and (3) What are the developmental trajectories over
one year of TM practice in frontal alpha lateral asymmetry, and frontal
EEG coherence during eyes-open tasks, eyes-closed rest and practice of the
Transcendental Meditation technique?
EXPERIMENT 1: CROSS-SECTIONAL STUDY OF FRONTAL
COHERENCE, FRONTAL ALPHA POWER RESTING
ASYMMETRY, AND MEASURES OF PERSONALITY
AND PSYCHOLOGICAL TRAITS
TM group) included 13 subjects (5 male and 8 females, age = 37.0 ± 10.5
TM group) included 12 subjects (6 male and 6 females, age = 42.3 ± 11.2
years), who had been practicing the TM technique for almost 22 years (21.9 ±
11.2 years). The difference in age was not statistically significant (F(1,24) =
1.46, p = .239). All subjects were right-handed by self-report, and reported
from individuals who wished to learn the Transcendental Meditation practice
but had not yet been instructed. Thus, these two groups shared an interest in
practicing the Transcendental Meditation technique. This research has been
approved by the University’s IRB, and subjects signed written consent before
during three conditions: a 5-min eyes-closed resting session, 10-min TM
session, and a computer-administered choice reaction-time (RT) task. The
requiring a response. Each trial contained a pair of one- or two-digit numbers
2Data are reported as mean ± standard deviation.
FRONTAL ASYMMETRY, COHERENCE, AND TM PRACTICE1523
(150 ms duration, 1 cm in height) in the center of the computer screen 1.5 s
apart. Subjects were asked to press a button in their left hand if the first
number was larger, or in their right hand if the second number was larger.
To assess psychological health, subjects were later mailed four pencil-and-
paper instruments measuring emotional stability, inner/outer orientation, moral
returned their tests by mail in an enclosed stamped envelope.
while sitting comfortably with eyes-closed. It does not involve attention or
control of the breath, or attention to the body, mind or senses, as does
technique involves turning the attention away from outer phenomena and
backdrop for mental activity. Transcendental Meditation practice begins with
is conducted by “the natural tendency of the mind to expand” (for further
discussion see [Maharishi, 1969; Roth, 1994; Travis et al., 2002]).
Measures of Personality and Psychological Traits.
Emotional stability: The emotional stability sub-scale from the International
Personality Item Pool was used. The International Personality Item Pool is the
Item Pool items are freely available on the Internet (http://ipip.ori.org/ipip/).
such as the Minnesota Multiphasic Personality Inventory or the California
Personality Inventory. Emotional stability represents the tendency for good
emotional adjustment, high self-esteem, low anxiety, security, and easiness
Inner/outer orientation: Baruss developed this scale to quantify a subject’s
worldview along a material (outer)-transcendental (inner) dimension (Baruss
& More, 1992). Subjects are given 38 statements like: “My spiritual beliefs
determine my approach to life.” Subjects respond on a 7-point Likert Scale.
This instrument has high item-total correlations (.56–.62) and high Cronbach
alpha coefficients (.82–.95) (Baruss & Moore, 1992). Scores on this scale
1524 F. TRAVIS AND A. ARENANDER
correlate highly with positive inner growth and meaningfulness of life (Baruss
& Moore, 1992). This scale yields a single number, which ranges from
−114 (materialistic: “conceptualizing consciousness in terms of information
processing”) to +114 (transcendental: “emphasize subjective features of
consciousness and declare its ontological primacy”).
Moral reasoning: Gibbs Socio-Moral Reflection Measure—Short Form
presents moral statements and asks subjects to describe why a moral act may be
important to them. For instance: “Keeping promises is important because...”;
or “Helping one’s friend is important because. ...” Gibbs has written an
levels (Gibbs et al., 1992).
The Socio-Moral Reflection Measure can be group administered as a
pencil-and-paper test, takes 15–20 min to complete, and can be scored in
25 min. In addition, a scorer can gain competency in 25–30 hours of self-study.
Gibbs’s Socio-Moral Reflection Measure has high test-retest reliability (r =
Reflection Measure are highly correlated with scores on Kohlberg’s Moral
to administer and to score.
Levels of moral reasoning shift from surface considerations to an inner
autonomous basis for decision making. This progress is seen developmentally
from childhood to adulthood and parallels growth in cognitive development,
ego development, and self-concept (Alexander et al., 1990; Gibbs et al., 1992;
Anxiety levels: Spielberger’s State/Trait Anxiety assesses transitory feelings
of anxiety (state anxiety) and chronic feelings of anxiety (trait anxiety).
High trait anxiety levels are considered a general risk for psychological and
(Friedman & Booth-Kewleys, 1987; Watson & Clark, 1984). Anxiety is one
dimension of the emotional stability personality subscale.
EEG Recording Details. EEG was recorded during 5-min eyes-closed rest,
10-min TM practice, and computerized reaction-time tasks from F3, Fz, F4,
C3, Cz, C4, P3, Pz, and P4 in the 10–20 system using silver/silver-chloride
electrodes affixed with EC-2 cream, a forehead ground, impedances at 5 kohms
or less, and a linked-ears reference (for a more detailed description of the
methods and tasks see Travis et al. (2002). EEG signals were recorded with a
FRONTAL ASYMMETRY, COHERENCE, AND TM PRACTICE1525
.01–100 Hz band pass filter (3 dB down, 12 dB octave/slope). All signals were
digitized on line at 256 points/s, and stored for later analyses using EEGSYS, a
standardized research acquisition and analysis package developed in conjunc-
tion with researchers at the National Institutes of Health (Hartwell, 1995).
Data Analysis: Standardized Tests of Personality and Psychological
Traits. The tests of inner/outer orientation, state/trait anxiety, and emotional
stability were scored using standard templates. Gibbs’s moral reasoning
protocols were sent to two trained scorers. They met the requirements for
reliability in scoring, set forth in Gibbs’s manual, Appendix B and C (Gibbs
et al., 1992). These two raters correlated .92 on their ratings of the Moral
Reasoning protocols. These tests yielded five psychological measures—three
of positive psychological traits and two measures of negative traits.
Data Analysis: EEG. Lateral asymmetry was calculated from EEG recorded
during the eyes-closed rest period. Broadband coherence was calculated from
EEG recorded during the choice reaction time task. This was done to compare
with the literature on brain changes during different meditation practices.
This EEG analysis yielded two brainwave measures—alpha frontal resting
asymmetry and broadband frontal task coherence. These brainwave measures
were correlated with scores on paper-and-pencil tests.
Frontal EEG alpha resting asymmetry: The resting eyes-closed data were
analysis (less than 5% of epochs). Following Davidson’s protocol (Davidson
et al., 2003b), the data were fast Fourier transformed in one-second and
epochs during the first two minutes of the eyes-closed session. Frontal (F3
and F4) power was calculated in the alpha frequency (8–13 Hz) (Davidson
et al., 2000b; Pivik et al., 1993). The frontal alpha asymmetry score was
calculated by subtracting log-transformed left hemisphere alpha power (F3)
from log-transformed right-hemisphere alpha power (F4). Greater positivity in
this measure is considered to reflect greater left hemisphere activation (reduced
left hemisphere alpha activity). It could also mean similar left-hemisphere
alpha activity between groups along with increased alpha activity in the right
hemisphere in one group or condition.
Frontal EEG coherence during tasks: The first 2-s epochs of each trial
were manually inspected for artifacts. Any epochs with artifacts were marked
and excluded from the data analysis (less than 7% in these data). These
1526 F. TRAVIS AND A. ARENANDER
two-second epochs included the 100 ms baseline, first stimulus presentation,
1.5-s interstimulus interval, second stimulus presentation, and 400 ms after
presentation of the second stimulus. The actual response, with movement
artifacts, occurred after this 2-s period. Thus, this period was relatively free
of artifacts and contained a consistent series of cognitive processes. Following
Travis’s protocol (Travis et al., 2002), these data were fast Fourier transformed
in 2-s epochs, and frontal (F3-F4) coherence was calculated in a broadband
The group with extensive TM experience exhibited significantly higher values
of frontal alpha asymmetry, frontal EEG coherence, and positive psychological
traits, and significantly lower values of negative psychological traits. A
MANOVA with group as the between factor and the two brainwave measures
and five psychological measures as variates yielded a significant main effect
for group (Wilk’s Lambda F (7, 17) = 4.65; p = .005). Table 1 contains the
means, standard deviations, F statistic, and p-values from individual ANOVAs
for the seven variables.
Table 1. Group means, standard deviations, F-statistics (1,24) and p-values for the two frontal
brain measures (alpha resting asymmetry and broadband task coherence) and the five measures of
personality and psychological traits
Control = 12; TM = 13.
FRONTAL ASYMMETRY, COHERENCE, AND TM PRACTICE 1527
Figure 1. Mean and Standard Deviation of Log F3 and F4 Power in Control and TM Subjects.
Alpha asymmetry differences between these groups appeared to have resulted from higher right-
hemisphere alpha power.
Because lateral asymmetry is a difference-variable, so-called left lateral-
alpha power), or greater right-hemisphere (F4) alpha power. Figure 1 presents
the log power values at F3 and F4 for both groups. Statistically significant
lateral asymmetry values between these groups appeared to have resulted from
higher right hemisphere alpha power, F(1, 23) = 4.28, p = .051. There were
no group differences in left hemisphere alpha power, F(1, 23) = 1.51, p =
.232. The TM subjects also had higher alpha power overall (MANOVA, Wilk’s
Lambda F(2,22) = 5.86, p = .009). Higher overall alpha power has previously
been reported in long-term TM subjects during eyes-closed rest and eyes-open
tasks (Travis et al., 2002).
The relations between the brainwave and psychological variables were
assessed with a Pearson correlation analysis and are presented in Table 2.
Frontal alpha asymmetry correlated moderately with EEG coherence (r = .33)
and weakly with the five psychological and personality variables (range of r =
.08 to .28). In contrast broadband frontal coherence correlated highly with all
variables. Table 2 presents the correlation estimates for these seven variables
as well as Spearman rho of group with each of these variables. Statistically
significant correlations are in bold.
1528 F. TRAVIS AND A. ARENANDER
Table 2. Correlation table of five psychological variables and two brainwave variables (Pearson
correlation) and group membership (Spearman rho). Statistically significant correlations are in
Asymmetry Coherence MoralOrient. Stability StateTrait
This exploratory cross-sectional study suggests that broadband frontal coher-
This finding is preliminary because initial group differences are not known in a
age, and interest in the Transcendental Meditation technique. There could,
however, have been other systematic differences between the two groups that
contributed to the observed differences in brain functioning and psychological
The next study used a longitudinal study to more reliably assess the
relation of Transcendental Meditation practice, frontal alpha asymmetry, and
frontal coherence. This study investigated brain patterns over one year in
three conditions: eyes-closed rest, Transcendental Meditation practice, and
EXPERIMENT 2: LONGITUDINAL TEST OF TM EFFECTS ON
FRONTAL ALPHA RESTING ASYMMETRY, AND FRONTAL
BROADBAND TASK COHERENCE
This second experiment used a longitudinal design with each subject serving
as his or her own control. To strengthen the design: (1) subjects were measured
at three posttests; (2) non-equivalent dependent variables were measured (task
coherence and alpha resting asymmetry), and (3) measurements were recorded
during three independent conditions (eyes-closed rest, TM practice, and eyes-
open computer tasks) (Shadish et al., 2002, pp. 110–111).
FRONTAL ASYMMETRY, COHERENCE, AND TM PRACTICE 1529
Subjects. Fourteen subjects participated in this study as part of the Uni-
versity’s ongoing student evaluation program. Subjects comprised 9 males
and 5 females with an average age of 27.5 years ± 9.6 years. All subjects
were right-handed, and reported good health with no history of accidents,
hospitalization, or psychiatric diseases. This research has been approved by the
University’s IRB, and subjects signed written consent before the research.
Procedure. EEG was recorded during three conditions: (1) 5-min eyes-
closed resting session, (2) computer-administered choice reaction-time task, as
recorded on this schedule to avoid possible sequence effects of TM practice on
EEG Recording Details. EEGwasrecordedfromF3,Fz,F4,C3,Cz,C4,P3,
EEG Analysis Details. The data were first manually inspected for artifacts.
These were marked and excluded from subsequent analyses. Fewer than
5% of epochs contained artifacts in these data. The data were then fast
Fourier transformed in one-second epochs during the first two minutes of the
eyes-closed rest and TM sessions, and during two-second epochs containing
the choice reaction time (RT) tasks, as in the first experiment. Frontal alpha
asymmetry, and broadband frontal coherence were calculated as detailed in
experiment one during the three conditions—resting, reaction time tasks, and
Transcendental Meditation practice.
Statistical Tests. Following published recommendations for psychophysio-
logical measures (Jennings et al., 1987; Keselman, 1998), MANOVAs were
used to test for longitudinal differences in coherence and lateral asymmetry.
If significance differences were found, then repeated measures ANOVAs were
used to investigate the slope of the change over time.
Results and Discussion
Frontal Alpha Power Asymmetry. There were no significant pre–post
test differences in alpha asymmetry over the year in any of the three
1530 F. TRAVIS AND A. ARENANDER
Figure 2. Mean and Standard Deviation of Frontal Alpha Asymmetry Levels over one year in the
three conditions. Alpha asymmetry did not significantly change over one year during eyes-closed
rest, practice of the Transcendental Meditation technique, or the eyes-open choice reaction time
tasks, although there were significant condition differences—the two eyes-closed conditions (rest
and TM) had more left-lateralized activation than during the choice reaction time task.
differences, reflecting the demands of each task. Lateral symmetry during
eyes-closed rest and Transcendental Meditation practice were significantly
more left lateralized that during the reaction time task (F(2,42) = 10.8, p <
.0001) with no differences between the two eyes-closed conditions (F(1,14) <
1.0, ns.) Figure 2 presents the frontal alpha asymmetry values at baseline, 2,
6, and 12 months posttest for the three conditions: eyes-open tasks (grey line),
eyes closed rest (solid line), and TM practice (dashed line).
Frontal Broadband Coherence. Figure 3 presents broadband frontal co-
herence values at baseline, 2, 6, and 12 months posttest during eyes-open
tasks (gray line), eyes closed rest (solid line), and TM practice (dashed line).
Statistical tests revealed significant main effects for both time (pre–post test)
and condition (rest, TM, and task) in broadband frontal coherence.
Longitudinal differences: MANOVAs revealed a significant main effect for
time in frontal broadband EEG coherence during eyes-open computer tasks
(F(3,11) = 4.9; p = .021), during eyes-closed rest (F(3,11) = 3.59; p =
.05), and during TM practice (F(3,11) = 5.5; p = .017). Repeated measure
ANOVAs revealed a significant linear trend in EEG coherence from baseline
to the three posttest-recordings during tasks (F(1,13) = 14.5; p = .002) and
FRONTAL ASYMMETRY, COHERENCE, AND TM PRACTICE1531
Figure 3. Mean and Standard Deviation of Broadband Frontal Task Coherence over one year.
Frontal coherence changed significantly over the one year in each of the three conditions.
during eyes-closed rest (F(1,13) = 8.8; p = .011), and a significant quadratic
trend or step-function in EEG coherence during TM practice (F(1,12) = 11.8;
p = .005). During TM practice, individual comparisons revealed a significant
increase in broadband frontal coherence from baseline eyes-closed rest to the
2 month TM recording (F(1,13) = 18.3; p = .001) and no significant changes
in frontal broadband coherence between 2, 6, and 12 month posttests (F (2,24)
< 1.0, ns).
Conditions differences: Within MANOVAs compared broadband frontal
coherence between the three conditions. Coherence during TM practice was
significantly higher than during eyes-closed rest (F(1,13) = 8.2; p = .013),
and coherence during eyes-closed rest was significantly higher than during the
eyes-open computer tasks (F(1,13) = 29.2; p <.0001.)
try did not significantly change during one year of Transcendental Meditation
trait that either does not change due to TM practice or it changes very
slowly. This conclusion is supported by other studies that report EEG frontal
1532 F. TRAVIS AND A. ARENANDER
alpha asymmetry is stable over time across waking, sleeping, and dreaming
(Benca et al., 1999). In addition, although Davidson’s research reported
significant changes in central leads after 8 weeks Mindfulness meditation
practice (Davidson et al., 2003b); no significant changes were reported for
prefrontal leads (F3 and F4, or F7 and F8) (Travis & Arenander, 2004).
broadband coherence were seen during one-year practice of the Transcendental
Meditation technique across all conditions, although the slope within each
and TM practice support earlier findings that brainwave changes during TM
practice are stabilized after a relatively short period of TM practice, and that
the effects of TM practice over time may be more evident in brainwave patterns
outside of meditation (Travis et al., 2002).
Possible Effects of a Linked-Ears Reference on the Findings
A linked-ears reference may distort EEG power and coherence spectra. Frontal
power spectra of linked-ears reference data often have peaks that correspond
to posterior EEG patterns, and the coherence spectra are significantly higher
with linked-ears data compared to reference-free data such as close bi-polar or
current source density (Fein et al., 1988; Travis, 1994). In this study, possible
linked-ears confounds would have been similar in all conditions. Thus, the
patterns in coherence and alpha asymmetry over time and between conditions
probably reflect conditions-effects rather than reference-artifacts.
These studies focused their investigation on lateral asymmetry and coherence
between frontal leads because these two measures have been reported
to best characterize two different meditation practices—Mindfulness and
(1) data from a dense-array of frontal electrodes to identify the spatial extent
of these findings, (2) contributions of other scalp areas, and (3) effects of using
“reference free” data, resulting from a Laplacian transform, on patterns of
lateral asymmetry and coherence (Fein et al., 1988; Nunez et al., 2001).
Four conclusions emerge from the current study. First, EEG frontal
coherence, compared to alpha frontal asymmetry, appears to be a better
index of TM-effects on brain functioning. In the first experiment, larger
group differences were seen in frontal coherence than in lateral asymmetry
FRONTAL ASYMMETRY, COHERENCE, AND TM PRACTICE 1533
and coherence correlated more highly with measures of personality and
psychological traits than did lateral asymmetry. In the second experiment,
lateral asymmetry did not significantly change over the year of regular
TM practice. In contrast, coherence changed significantly during all three
conditions—eyes-closed rest, Transcendental Meditation practice, and choice
reaction time tasks.
Nunez explains the possible effects of local, intermediate, and long range
or global synchrony on EEG power and coherence (Nunez et al., 2001). EEG
power levels reflect the intermediate synchrony between cortical columns (1–3
cm), whereas EEG coherence levels reflect long range or global synchrony
between spatial-distributed cortical areas (10–25 cm). Changes in EEG power
(intermediate synchrony) thus occur on the “background environment” of
global synchrony (Nunez, 2000; Nunez et al., 2001), which facilitates and
organizes synchrony between cortical columns. In terms of Nunez’s model,
practice of the Transcendental Meditation technique appears to enhance the
“background environment” of frontal connectivity, as reflected in increased
broadband coherence both during the practice and after the practice. Some
researchers consider broadband coherence as a mechanism for binding spatial
separate cortical activity into the unity of conscious experience (Varela et al.,
may signal a more integrated style of frontal executive functioning that
may be termed “whole brain functioning.” Previous research reports that
increased frontal coherence is associated with improved neurophysiological
integration (Wallace et al., 1983), cognitive flexibility (Dillbeck et al., 1981),
and performance on attentional tasks (Travis et al., 2002).
A second conclusion is that broadband frontal EEG coherence during
tasks appears to be associated with improved cognitive functioning and mental
health. Frontal EEG coherence was positively correlated with moral reasoning,
emotional stability, inner orientation, and inversely correlated with both state
and psychological measures were much lower (<.30) and did not reach
after a few months practice. High broadband coherence levels were reached
within two months practice of the Transcendental Meditation technique.
Coherence estimates remained at these high levels at 6 and 12 months. The
lack of apparent TM “practice effects” in EEG patterns may be an important
meditation practices. This replicates previous findings (Travis et al., 2002).
1534 F. TRAVIS AND A. ARENANDER
A fourth related conclusion is that long-term effects of TM practice on
brain dynamics are more clearly evident during activity, rather than during
meditation. Although significant increases in coherence were seen during TM
practice after two months practice, effects of regular TM practice at 6 and 12
months were seen during tasks outside of the practice itself. This replicates
previous findings (Travis, 1991; Travis et al., 2002). The unique brainstate
cultured during TM practice, as measured by frontal coherence, appears to
be integrated with waking brainstates outside of meditation (Travis et al.,
2000, 2002) and may provide an enhanced understanding of human mind/body
potential (Travis et al., 2004).
Together, the early efficacy of TM practice combined with progressive
changes in brain dynamics during waking tasks may constitute two important
It is possible that these two criteria could serve as benchmarks to compare
different meditation techniques, which generate different meditative brain
states. In addition, future comparative meditation research may benefit from
inclusion of coherence measures across multiple frequency bands, during the
practice, as well as during waking tasks. A collaborative effort of different labs
could use a common set of brain measures to study their particular meditation
tradition. Such a collaborative effort would enhance the understanding of
similarities and differences between meditation and spiritual traditions.
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