ORIGINAL RESEARCH
published: 18 November 2021
doi: 10.3389/fpsyg.2021.745344
Advanced Meditation Alters
Resting-State Brain Network
Connectivity Correlating With
Improved Mindfulness
Ramana V. Vishnubhotla 1 , Rupa Radhakrishnan 1 , Kestas Kveraga 2 , Rachael Deardorff 1 ,
Chithra Ram 3 , Dhanashri Pawale 4 , Yu-Chien Wu 1 , Janelle Renschler 4 ,
Balachundhar Subramaniam 2 and Senthilkumar Sadhasivam 4*
1
Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN, United States,
Department of Anesthesia, Critical Care and Pain Medicine, Sadhguru Center for a Conscious Planet, Beth Israel
Deaconess Medical Center, Boston, MA, United States, 3 Department of Radiology, School of Medicine, University
of Louisville, Louisville, KY, United States, 4 Department of Anesthesia, Indiana University School of Medicine, Indianapolis,
IN, United States
2
Edited by:
Sisir Roy,
National Institute of Advanced
Studies, India
Reviewed by:
Xize Jia,
Hangzhou Normal University, China
Justine Megan Gatt,
Neuroscience Research Australia,
Australia
*Correspondence:
Senthilkumar Sadhasivam
ssenthil@pitt.edu
Specialty section:
This article was submitted to
Consciousness Research,
a section of the journal
Frontiers in Psychology
Received: 21 July 2021
Accepted: 15 October 2021
Published: 18 November 2021
Citation:
Vishnubhotla RV,
Radhakrishnan R, Kveraga K,
Deardorff R, Ram C, Pawale D,
Wu Y-C, Renschler J, Subramaniam B
and Sadhasivam S (2021) Advanced
Meditation Alters Resting-State Brain
Network Connectivity Correlating With
Improved Mindfulness.
Front. Psychol. 12:745344.
doi: 10.3389/fpsyg.2021.745344
Purpose: The purpose of this study was to investigate the effect of an intensive 8-day
Samyama meditation program on the brain functional connectivity using resting-state
functional MRI (rs-fMRI).
Methods: Thirteen Samyama program participants (meditators) and 4 controls
underwent fMRI brain scans before and after the 8-day residential meditation program.
Subjects underwent fMRI with a blood oxygen level dependent (BOLD) contrast at
rest and during focused breathing. Changes in network connectivity before and after
Samyama program were evaluated. In addition, validated psychological metrics were
correlated with changes in functional connectivity.
Results: Meditators showed significantly increased network connectivity between the
salience network (SN) and default mode network (DMN) after the Samyama program
(p < 0.01). Increased connectivity within the SN correlated with an improvement in selfreported mindfulness scores (p < 0.01).
Conclusion: Samyama, an intensive silent meditation program, favorably increased the
resting-state functional connectivity between the salience and default mode networks.
During focused breath watching, meditators had lower intra-network connectivity in
specific networks. Furthermore, increased intra-network connectivity correlated with
improved self-reported mindfulness after Samyama.
Clinical Trials Registration: [https://clinicaltrials.gov], Identifier: [NCT04366544].
Registered on 4/17/2020.
Keywords: meditation, Samyama, Isha yoga, mindfulness, fMRI, brain networks, salience network, default mode
network
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Meditation Alters Network Functional Connectivity
this study also mentioned improvements in joy, mindfulness,
resilience, and vitality (Sadhasivam et al., 2021). Participants at
an Inner Engineering (IE) program, a comprehensive beginnerlevel yoga program, reported lower levels of perceived stress and
higher general well-being after practice (Peterson et al., 2017).
Another study demonstrated increased anandamide levels for
participants in the Bhava Spandana Program (BSP), a second level
meditation retreat (Sadhasivam et al., 2020). Gamma power was
shown to increase during three types of meditation (Braboszcz
et al., 2017), one of which is Shoonya meditation. Shoonya
meditation is a conscious process of non-doing. It is taught in
combination with Shakti Chalana Kriya, a breath-based yogic
practice (pranayama). Other Isha yoga and meditation programs
have also shown benefits such as improved visual plasticity
(Braboszcz et al., 2013) and improved cardiac function (Selvaraj
et al., 2008; Muralikrishnan et al., 2012). The Shoonya Program,
IE and BSP are all prerequisites for the Samyama Program.
Blood oxygen level dependent (BOLD) functional magnetic
resonance imaging (fMRI) is a commonly utilized technique to
assess brain activity (Bandettini et al., 1992; Ogawa et al., 1992).
This technique indirectly measures brain activity by detecting
changes in relative blood concentrations of blood oxygen
and deoxyhemoglobin (dHb). During task-related neuronal
activation at localized regions, increases occur in cerebral blood
flow which results in local reduction in deoxyhemoglobin and
increase in local oxyhemoglobin. The blood oxygenation leveldependent (BOLD) MRI contrast is dependent on changes in
dHb, which acts as an endogenous contrast enhancing agent
and serves as the source of the signal for fMRI (Faro et al.,
2017). However, there are spontaneous temporally synchronized
fluctuations in brain neuronal activity at rest, that are referred
to as the resting state networks (Biswal et al., 1997). More
than 20 resting state functional networks have been described
so far; amongst those, interplay between three networks – the
salience, default mode, and frontoparietal (executive) networks,
are thought to be important for understanding mechanisms
associated with meditation (Raffone et al., 2019).
Various studies on meditative practices like Soham (Guleria
et al., 2013), Buddhist tradition of Samatha (Wallace, 2001),
Kundalini yoga (Yang et al., 2016), Zen (Ritskes et al., 2003),
and Transcendental Meditation (Mahone et al., 2018) practices
have shown differences in their brain activation centers (Mishra
et al., 2017). Following various meditation techniques, activity
is relatively commonly seen in the dorsolateral prefrontal cortex
(dl-PFC) (Ritskes et al., 2003), anterior cingulate cortex (ACC)
(Tang et al., 2015b; Mahone et al., 2018), and left prefrontal cortex
(PFC) (Baerentsen et al., 2010). Brain network connectivity has
been shown to be impacted by meditation (Brewer et al., 2011;
Hasenkamp and Barsalou, 2012).
With the reported psychological benefits of advanced
meditation retreats (Sadhasivam et al., 2020, 2021), it is important
to assess the physiological impact of these programs on the
brain with advanced meditation program, Samyama. This novel
study focused on assessing the changes in functional connectivity
before and after the Samyama Program using resting-state fMRI
(rs-fMRI) besides correlating the connectivity changes with
improved mental wellbeing.
INTRODUCTION
Meditation is increasingly being recognized as an effective
method to improve psychological wellbeing. A 2014 metaanalysis of 47 trials found that meditation could lower depression,
anxiety, pain, and stress/distress, as well as improve mental
health-related quality of life (Goyal et al., 2014). Research has also
revealed meditation-related structural and physiological changes
in the brain and nervous system (Lazar et al., 2005; Hölzel
et al., 2011; Dodich et al., 2019; Yang et al., 2019). Recently,
we showed that Samyama program, an intensive meditation
program significantly and effectively reduced depression, anxiety
while improving physical health (Sadhasivam et al., 2021).
This study aimed to demonstrate functional brain changes in
Samyama meditators before and after the program, in addition
to correlating the functional changes to improved mental health.
Anxiety has been associated with changes in brain activity
(Bishop, 2007) such as reduction in prefrontal activity (Bishop,
2009) and alteration in the default mode network (Zhao et al.,
2007). Impairment of the default mode network has also been
linked to social phobia (Gentili et al., 2009). Positive emotions
have also been linked to specific regions. For example, one study
showed that relative happiness is correlated with rostral anterior
cingulate cortex gray matter density (Matsunaga et al., 2016)
and remembering happy events has been linked to activation
in the anterior cingulate cortex, prefrontal cortex, and insula
(Suardi et al., 2016). Functional connectivity was greater for
reward, motivation and emotion regulation network in groups
who were “in love” compared to those who were single or
ended a relationship (Song et al., 2015). Taken together, this
demonstrates the utility of neuroimaging in understanding brain
processes involved in both positive and negative emotions.
Neuroimaging can therefore give us further insight into brain
networks affected by meditation.
The Yoga Sutras, a comprehensive set of ancient texts about
yoga written by Patanjali, describe 8 limbs or branches of
yoga. These include: (1) Yama (ethical standards), (2) Niyama
(self-discipline), (3) Asana (postures), (4) Pranayama (breath
control), (5) Pratyahara (withdrawal from senses), (6) Dharana
(concentration), (7) Dhyana (contemplation), and (8) Samadhi
(union). A combination of the last three is referred to as a
process called Samyama. Though Samyama has been around
for thousands of years, it has not been scientifically investigated
until now. Samyama Program is an 8-day silent residential
meditation experience offered by the international non-profit
Isha Foundation. Samyama is a rigorous meditation program
offered by Isha Foundation for the general population, requiring
a substantial number of prerequisite programs and preparation
to attend. Preparation to participate in the program requires
about 2 months of vegan diet and daily practice of hatha
yoga (physical postures), kriya yoga (breathing and sound), and
Shoonya meditation (conscious non-doing).
In our recent study, Samyama participants had reduced
depression and anxiety and improved subjective well-being
scores and health biomarkers (HbA1c, body weight, and lipid
profile) compared with their baseline values, and compared
to their household non-meditator controls. Participants in
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Samyama Program
MATERIALS AND METHODS
During the program, participants were to remain silent for
the entire 8-day duration of the program. The program hall
was closed to external influences. No specific instructions or
programs were given to the controls, and controls did not
practice any meditation.
Samyama Participant Recruitment
These subjects were a subset of the participant group used for
an earlier study (Sadhasivam et al., 2021). The Isha Institute
of Inner Sciences (McMinnville, TN, United States) provided
a registration list for the April 2018 Samyama Program.
Each applicant was then individually assessed by an Isha
Foundation instructor for suitability to attend the program. The
requirement for participation in the Samyama retreat included
prior completion of 4 Isha programs (Inner Engineering, Bhava
Spandana Program, Shoonya Meditation, and Yogasanas) and a
commitment to continue preparatory practices 2 months before
the Samyama retreat.
Study eligibility criteria included: Samyama participant and
interested cohabitating spouse/partner, at least 18 years of age.
Exclusion criteria were: inability to read or comprehend the
consent form; subjects with medical conditions in which blood
sampling would be contraindicated (e.g., severe anemia); active
use of marijuana, opioids, or related drugs; use of antibiotics or
probiotic/prebiotic supplements within 60 days of enrollment;
participants living outside of the country.
MRI
All MR imaging was performed on a Siemens PRISMA 3.0
Tesla Scanner (Siemens, Erlangen, Germany) using a 32-channel
head coil. Images acquired included anatomic T1-weighed 3D
magnetization-prepared rapid acquisition with gradient echo
(MPRAGE; repetition time / echo time [TR/TE] = 2010/2.91 ms,
flip angle = 9◦ , field of view = 192 × 174 mm, 192 sagittal
slices, isotropic voxel size of 1 mm) and BOLD rs-fMRI
with a gradient-echo planar imaging (EPI) sequence (Axial,
TR = 760 ms, TE = 29 ms, flip angle = 54◦ , 55 slices, field of view
[FOV] = 220 × 220 mm2 , isotropic voxel 2.5 mm, simultaneous
multi-slice [SMS] factor 5, 790 volumes). A spin-echo-EPI with
reverse phase encoding and matched imaging parameters was
also performed for geometric distortion correction.
For both meditator and control groups, the first run of
the fMRI was performed at rest. The second run of the fMRI
was performed with instructions to focus on their breathing
technique, which is a part of the meditation practice.
Study Approvals
The study was reviewed and approved by the Institutional Review
Board of the Indiana University School of Medicine. Participants
and controls provided electronic informed consent.
Functional Magnetic Resonance Imaging
Processing
Samyama Participant Dietary
Requirements
After visual assessment of quality of the anatomic and BOLD
data, fMRI was preprocessed using the standard pipeline
with FMRIB Software Library (FSL; Oxford, United Kingdom)
(Jenkinson et al., 2012). Fieldmap correction was performed
using FSL topup (Andersson et al., 2003; Smith et al., 2004).
After initial preprocessing was done in FSL, the rest of the
preprocessing and fMRI analysis was performed with CONN
Toolbox (Cambridge, MA, United States) (Whitfield-Gabrieli
and Nieto-Castanon, 2012; Nieto-Castanon, 2020). Functional
MRI data was realigned using the realign & unwarp function
in SPM12 (Andersson et al., 2001). For outlier detection, we
used a 97th percentile with a global signal z-value threshold
of 5 and subject motion threshold of 9 mm. Functional and
structural MRI data were then normalized to the standard
Montreal Neurological Institute (MNI) T1 template using a
direct normalization process. Data was segmented into gray
matter, white matter, and cerebrospinal fluid (CSF) (Ashburner
and Friston, 1997, 2005). Isotropic resolution of 1 mm for
structural images and 2 mm for functional images were used.
Next, the data was smoothed using spatial convolution with a
Gaussian kernel of 8 mm full width half maximum (FWHM)
(Nieto-Castanon, 2020).
Denoising involved removing of noise from white matter
and CSF (Behzadi et al., 2007; Chai et al., 2012), estimated
subject motion parameters including 3 translation and 3 rotation
parameters (Friston et al., 1996), scrubbing (Power et al., 2014),
and session effects. For temporal band pass filtering, the lower
frequency threshold was 0.008 Hz and the upper frequency
As part of the Samyama preparatory process (60 days before the
program), meditators were required to follow a vegan diet with at
least 50% raw foods consumed. They were encouraged to avoid
foods which may be considered “negative pranic,” or negative
to life energy, including garlic, onion, chili, eggplant, asafoetida,
coffee, and tea. Additionally, use of alcohol, cigarettes, stimulants,
and illicit drugs was discouraged.
Samyama Participant Practice
Requirements
Samyama participants, also referred as meditators, were asked to
perform the following practices daily for the 60-day preparation
period. These include kriya yoga practices (Shakti Chalana
Kriya and Shambhavi Mahamudra Kriya), hata yoga (Surya Kriya
and Yogasanas), Shoonya meditation twice a day, Sukha Kriya
and Arda Siddhasana for at least 1 h per day. Kriya yoga
practices are combinations of posture, breath, and sound that
are meant to purify and enhance the flow of one’s energies while
simultaneously increasing general stability. Hata yoga practices
consist of postures, meant to improve flexibility and strengthen
the body. Shoonya meditation is a process of conscious nondoing. Sukha Kriya consists of alternate nostril breathing which
leads to regulation of breath. Ardha Siddhasana is a posture in
which one sits cross-legged with the heel of the left foot placed
at the perineum.
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threshold was 0.09 Hz. Filtering was performed after regression to
avoid mismatch in nuisance regressor procedure (Hallquist et al.,
2013; Nieto-Castanon, 2020).
Connectivity was assessed between regions of interest
(ROIs). ROI-to-ROI analysis was performed for structures
in predetermined networks (see “Brain Networks” section).
Comparisons were made within program participants
(meditators) before and after the program for both restingstate and focused breathing conditions and corrected for
multiple comparisons using FDR threshold of <0.05. Age,
gender, and prior participation in the program were entered
as co-variates of no interest.
psychological scores before and after the program. Beforeafter comparisons were performed with the after condition
greater than the before. Comparisons between meditators and
controls were performed with meditators greater than controls.
Comparisons with psychological scores were also compared with
the after condition greater than before. A corrected p-value of less
than 0.05 was considered significant.
RESULTS
Demographics
We recruited 24 study subjects, 18 Samyama participants
(meditators) and 6 controls. In the final analysis, 13 Samyama
meditators (8 men and 5 women), and 4 controls (2 men and 2
women) were included (Figure 1). The reasons for exclusions are
included in a Consort diagram (Figure 1). Demographic data is
shown in Table 1.
Brain Networks
Four brain networks were studied – default mode network
(DMN), salience network (SN), frontoparietal network (FPN),
and dorsal attention network (DAN). The default mode network
includes the medial prefrontal cortex (mPFC), posterior cingulate
cortex, precuneus, and angular gyrus and is involved with
reflective processes (Buckner et al., 2008; Andrews-Hanna, 2012).
The salience network primarily includes the anterior cingulate
cortex and the anterior insula (AI) and is involved with filtering
and prioritizing signals received from external cues (Menon and
Uddin, 2010). This network also plays an important role in
switching between central executive and default mode networks
(Sridharan et al., 2008). The frontoparietal network, also known
as the central executive network (CEN), primarily includes the
dorsolateral prefrontal cortex (dl-PFC), and posterior parietal
cortex (PPC) and is involved with executive functions and
cognitive control (Marek and Dosenbach, 2018). Finally, the
dorsal attention network includes the intraparietal sulcus (IPS)
and front eye fields (FEF) and is involved with voluntary attention
(Kincade et al., 2005).
Meditator Functional Magnetic
Resonance Imaging Networks Altered
After Samyama
Resting state functional connectivity between regions in the
SN and DMN were significantly altered in participants after
the Samyama program compared to pre-Samyama (Figure 2A).
Intra-network connectivity (connectivity between ROIs in the
same network) within the SN and DMN was reduced (Figure 2B)
during focused breath watching after Samyama program
compared to pre-Samyama. In controls, there were no significant
changes in functional connectivity for both resting state and
focused breathing conditions between the two time points (data
not shown). Both resting state and focused breathing data is
summarized in Table 2. These results demonstrate connectivity
changes with the salience and default mode networks after
Psychological Factors
Psychological scores were taken from a subset from a previous
study (Sadhasivam et al., 2021). Scores for anxiety (Pilkonis et al.,
2011), depression (Andresen et al., 1994), mindfulness (Brown
and Ryan, 2003; Osman et al., 2016), joy (Shiota et al., 2006),
vitality (Bostic et al., 2000), and resilience (Smith et al., 2008)
were accessed with validated surveys. Psychological data was
normalized and entered as secondary co-variates in the analysis.
Statistical Analysis
Statistical analysis was performed with CONN Toolbox
(Whitfield-Gabrieli and Nieto-Castanon, 2012). Connectivity
between ROIs were assessed using a general linear model. Output
values included a t-stat with degrees of freedom, uncorrected
p-value (p-unc), and a false discovery rate p-value (p-FDR) when
corrected for multiple comparisons. Greater positive t scores
indicated stronger functional connectivity between regions while
greater negative scores indicated weaker functional connectivity
between regions.
Three sets of comparisons were performed – (A) comparisons
within the meditator group before and after the program,
(B) comparisons between meditators and controls at each time
point, and (C) comparisons within the meditator group with
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FIGURE 1 | 24 participants initially enrolled with 13 meditators and 4 controls
included in the final analysis.
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TABLE 2 | Comparison in meditator functional connectivity from before and after
Samyama program.
TABLE 1 | Demographic data of Samyama meditators and controls.
Meditators (n = 13)
Controls (n = 4)
ROI (Network)
ROI (Network)
T-stat
p-unc
p-FDR
Gender
Meditators resting state
Male
8
2
Female
5
2
ACC (Salience)
PCC (DMN)
4.73
0.0005
0.0047
34.9 (3.6)
62.8 (4.3)
ACC (Salience)
Precuneus (DMN)
5.09
0.0003
0.0047
Age in years (SE)
Prior participation
rPFC-R (Salience)
PCC (DMN)
5.32
0.0002
0.0017
Yes
4
1
rPFC-R (Salience)
Precuneus (DMN)
5.98
0.0001
0.0012
No
9
3
Meditators focused breathing
Samyama and these changes differ based on the resting state and
breath watching.
Meditator scans showed lower functional connectivity
between the DAN and DMN and within the DAN compared
to controls (Figure 3A). There were no significant differences
between meditators and controls in the focused breath watching
condition before Samyama program (Figure 3B). Following
completion of the Samyama, resting state scans showed less
connectivity between the DAN and FPN (Figure 3C). Focused
breath watching scans showed less connectivity between the
DMN and DAN and FPN. Additionally, there was reduced
intra-network connectivity in the DAN (Figure 3D). This data is
summarized in Table 3. This data demonstrates that meditators
had less functional connectivity compared to controls between
the dorsal attention and default mode networks and dorsal
attention, default mode, and frontoparietal networks.
SMG-L (Salience)
rPFC-R (Salience)
−3.8
0.0025
0.0293
SMG-L (Salience)
rPFC-L (Salience)
−3.51
0.0043
0.0293
SMG-L (Salience)
ACC (Salience)
−3.47
0.0046
0.0293
PCC (DMN)
Precuneus (DMN)
−3.9
0.021
0.0404
Precuneus (DMN)
Precuneus (DMN)
−3.9
0.021
0.0404
Regions of interest (ROI) – anterior cingulate cortex (ACC), posterior cingulate
cortex (PCC), rostral prefrontal cortex (rPFC), precuneus, and supramarginal gyrus
(SMG). Brain networks – salience network and default mode network (DMN).
A p-FDR < 0.05 was considered significant. Positive t-stat indicates increased
connectivity while a negative t-stat indicates decreased connectivity.
DISCUSSION
This novel study demonstrates that Samyama, an intensive
silent meditation program, increased the resting-state functional
connectivity between the salience and default mode networks.
Furthermore, increased intra-network connectivity correlated
with improved self-reported mindfulness after Samyama. The
Samyama meditators showed significant changes in functional
connectivity and while no changes were observed within the
non-meditator control group. Interestingly, the changes within
the meditator group differed based on task condition at resting
state and focused breath watching. During the focused breath
watching after the Samyama program, the meditators had less
functional connectivity than controls between the DAN, DMN,
and FPN (also referred to as CEN) for 3 of the 4 points
tested, demonstrating specific and dynamic meditation-related
changes in the brain.
In meditators, during the resting state, we found significant
increases in functional connectivity between regions in the
salience network and default mode networks, specifically between
the ACC and PCC and precuneus. We were also able to correlate
Mindfulness Score Correlates With
Changes in Functional Connectivity
We previously showed that Samyama participants had reduced
anxiety and depression and increased mindfulness, joy, vitality,
and resiliency (Sadhasivam et al., 2021) compared to their
pre-Samyama baseline values. Improved mindfulness scores
correlated with increased functional connectivity within the
SN between the SMG and ACC (p < 0.05) (Figure 4). We
did not observe any significant correlation between the fMRI
changes and scores for anxiety, depression, joy, vitality, and
resilience (Table 4).
FIGURE 2 | Changes in functional connectivity was observed in meditators and comparisons were made before and after the Samyama program. (A) Functional
connectivity was increased between the anterior cingulate cortex (ACC) of the salience network and posterior cingulate cortex (PCC) and precuneus of the default
mode network (DMN) in the resting state condition. The PCC also had increased connectivity to the rostral prefrontal cortex (rPFC). (B) Functional connectivity was
decreased within the salience network between the supramarginal gyrus (SMG) and ACC and rPFC in the focused breathing condition. Red indicates increased
connectivity and blue indicates decreased connectivity.
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FIGURE 3 | Functional connectivities were compared between meditators and controls for each condition. (A) Resting-state pre-program – meditators had
decreased connectivity between the front eye fields (FEF) and lateral parietal (LP) lobe and between the left and right intraparietal sulci (IPS). (B) Focused breathing
pre-program – no significant difference between the groups. (C) Resting-state post program – meditators had significantly reduced connectivity between the FEF and
dorsolateral prefrontal cortex (dl-PFC) and posterior parietal cortex (PPC). (D) Focused breathing post program – meditators had significantly reduced connectivity
between the dl-PFC and LP and the IPS and posterior cingulate cortex (PCC). Red indicates increased connectivity and blue indicates decreased connectivity.
improved mindfulness scores to increased connectivity with the
SN. This result corresponds with previous findings in literature
where increased mindfulness from meditation was linked with
increased functional connectivity between the SN and DMN
(Doll et al., 2015).
During focused breath watching, functional connectivity
within the salience and default mode networks uniquely reduced
after Samyama compared to the baseline and resting state,
demonstrating the ability of the meditators to voluntarily and
dynamically influence and control certain brain connectivity
based on meditation-related specific tasks such as focused breath
watching. This can potentially explain improved mindfulness,
concentration, cognitive control and executive function at the
resting state and ability of the meditators to focus on specific
meditation-related tasks and reduce connectivity in certain
brain networks compared to the resting state. The focused
breathing condition is a more internalized state than the resting
state. Internalized states, such as having one’s eyes closed,
have shown to elicit different responses in brain functional
connectivity than the eyes-open state (Agcaoglu et al., 2020;
Weng et al., 2020). Furthermore, there was greater connectivity
within the DMN and lower connectivity within the SN in
the eyes-closed group (Costumero et al., 2020). Considering
that the focused-breathing condition is a more internalized
state, it is interesting that our results showed less connectivity
within the DMN after Samyama. Since the task was focused
breathing, this could explain why connectivity within the DMN
was reduced; the DMN has been previously linked to states
of mind-wandering (Mason et al., 2007; Christoff et al., 2009;
Poerio et al., 2017).
This study has shown that the ACC had increased connectivity
in meditators and linked to improved mindfulness scores. The
ACC is a structure that has been linked to increased connectivity
due to improvements in attention in prior meditation studies
TABLE 3 | Comparison between meditators and controls for functional
connectivity at both time points and conditions.
ROI (Network)
ROI (Network)
T-stat
p-unc
p-FDR
Pre program resting state
FEF-L (DAN)
LP-L (DMN)
−3.62
0.0025
0.0476
IPS-R (DAN)
IPS-L (DAN)
−3.65
0.0024
0.0447
Post program resting state
FEF-R (DAN)
dl-PFC-L (FPN)
−4.64
0.0003
0.0033
FEF-R (DAN)
PPC-L (FPN)
−4.6
0.0003
0.0033
Post program focused breathing
Precuneus (DMN)
IPS-R (DAN)
−3.62
0.0025
0.0405
Precuneus (DMN)
IPS-L (DAN)
−3.36
0.0043
0.0405
LP-L (DMN)
dl-PFC-R (FPN)
−3.86
0.0015
0.0294
IPS-R (DAN)
Precuneus (DMN)
−3.62
0.0025
0.0258
IPS-R (DAN)
PCC (DMN)
−3.58
0.0027
0.0258
IPS-R (DAN)
IPS-L (DAN)
−3.09
0.0074
0.0469
Regions of interest (ROI) – front eye fields (FEF), lateral parietal (LP), intraparietal
sulcus (IPS), dorsolateral prefrontal cortex (dl-PFC), posterior parietal cortex (PPC),
and precuneus. Brain networks – dorsal attention network, default mode network
(DMN), and frontoparietal network (FPN). A p-FDR < 0.05 was considered
significant. Positive t-stat indicates increased connectivity while a negative t-stat
indicates decreased connectivity.
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ventral-rostral “affective” subdivisions, both regions have been
shown to make key contributions to emotional processing (Etkin
et al., 2011). Positive emotions, which regulate and diminish
negative emotions, have been associated with activation in the
sub genual ACC, ventromedial prefrontal cortex (PFC) and pregenual ACC (Wager, 2008). The medial prefrontal (mPFC) cortex
and ACC are activated with not only negative emotions, but also
positive emotions. Empathy for others experiencing pain and
one’s experience of pain activate the dorsal ACC/mPFC (Lamm
et al., 2011). Lesions of the dorsal ACC serve in treating chronic
pain (Wilkinson et al., 1999). Endogenously driven analgesia,
by means of the “placebo effect,” has been closely tied to the
pre-genual ACC, which is presumed to modulate regions that
generate opioid-mediated anti-nociceptive responses, such as
the amygdala and periaqueductual gray (Petrovic et al., 2002;
Eippert et al., 2009).
Interactions between the DMN, SN and the CEN are
thought to be key to understanding the mechanism of action
of meditative practices on the brain (Raffone et al., 2019). In
this study, we demonstrate unique and different changes in
functional connectivity in the resting state and focused breath
watching. The latter produces a more meditation-related taskbased changes in functional brain connectivity compared to
the resting state; therefore, specific tasks need to be included
when analyzing resting and meditation-related task-related
changes in fMRI. Even opening and closing eyes has shown to
impact salience and default mode networks (Costumero et al.,
2020). Additionally, experienced meditators would have different
regions of brain activation compared to novices (Baron Short
et al., 2010) and long-term meditators have shown significant
neural changes (Holzel et al., 2007; Luders et al., 2011; Fayed
et al., 2013; Engen et al., 2018). We have uniquely demonstrated
increased and decreased intra-network connectivity in advanced
meditators during the resting state and meditation-related
focused breath watching. Importantly, improved mindfulness
scores correlated with the functional brain connectivity changes
after the Samyama program.
We previously showed that participation in the Samyama
program decreased negative psychological states and boosted
positive psychological states (Sadhasivam et al., 2021). Here,
we were able to observe significant changes in functional
connectivity at rest and these changes could help explain the
positive findings in the previous study. This is significant because
it suggests that the effects of the Samyama program seem to
be maintained outside of a meditative practice and provides a
physiological measurement. It is also important to note that these
changes occurred over a relatively short period of 8 days.
The strengths of this study are that it objectively demonstrates
significant changes after the Samyama program in the meditator
group. Criteria for determining significance was stringent as it
accounted for multiple comparisons. It was also able to show,
with significance, different changes based on task condition.
Finally, it was able to correlate changes in mindfulness scores
to changes in functional connectivity. Taken together, this study
helps advance our understanding of the impact of meditation
on brain networks.
This study did have some limitations. There were a relatively
small number of meditators in this study due to a limited number
FIGURE 4 | In meditators completing surveys, changes in mindfulness scores
were correlated with changes in functional connectivity. There was increased
functional connectivity between the anterior cingulate cortex (ACC) and
supramarginal gyrus (SMG). Red indicates increased connectivity and blue
indicates decreased connectivity.
(Tang et al., 2015a). Meditative practices were also linked to
increased blood flow to this region (Zeidan et al., 2014; Tang
et al., 2015b; Mahone et al., 2018). While the role of the ACC has
been debated, it is generally thought to be involved in cognitive
control (Ridderinkhof et al., 2004), happiness (Matsunaga et al.,
2016; Suardi et al., 2016), attention (Kim et al., 2016; Wu et al.,
2017), and empathy (Lockwood et al., 2015). It is associated with
the salience network SN but has also been linked with executive
functions (Carter et al., 1999).
Another region linked with executive functions is the
prefrontal cortex which is associated with concentration,
decision-making and awareness (Allman et al., 1993) and is
a part of the CEN (Menon, 2011). Meditation has shown to
suppress DMN and increase functional connectivity between
DMN and CEN (Bauer et al., 2019) and CEN and attention
networks (Taren et al., 2017). Bauer et al. (2019) suggested a
neural mechanism by which the CEN negatively regulates the
DMN by showing gradual reconfiguration in DMN and CEN
in meditation state and post meditation state (state to trait)
by means of positive diametric activity (PDA); the reported
psychological well-being in long-term meditators was likely due
to trait changes caused by reconfiguration and recalibration of
network structure, or homeostatic plasticity (Davis, 2013; Hellyer
et al., 2017). This in turn causes reductions in DMN activity
and stronger anti-correlated coupling between CEN and DMN
(Mooneyham et al., 2017; Marusak et al., 2018).
Contrary to the early dichotomized view of the DMN
and CEN regions representing dorsal-caudal “cognitive” and
TABLE 4 | Correlation between changes in mindfulness scores and functional
connectivity in meditators.
ROI (Network)
ROI (Network)
T-stat
p-unc
p-FDR
SMG-R (Salience)
ACC (Salience)
3.88
0.0019
0.0359
Regions of interest (ROI) – supramarginal gyrus (SMG) and anterior cingulate
cortex (ACC). Brain network – salience network. A p-FDR < 0.05 was considered
significant. Positive t-stat indicates increased connectivity while a negative t-stat
indicates decreased connectivity.
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Meditation Alters Network Functional Connectivity
of Samyama participants throughout the USA that were willing
to visit Indiana University MRI scanner twice, before and after
the Samyama program. Though the number of meditators in the
final analysis is relatively small, we did pre- and post-Samyama
MRIs in the meditators, having them as their own controls.
Second, Samyama meditators were involved with 2 months of
intensive preparation before experiencing the 8-day program.
Therefore, the meditator group may already have some changes
prior to the program which may not be reflected in the control
group. We report statistically significant, objective and consistent
changes in the meditators post-Samyama. The task related
changes (during focused breath watching) were consistently and
objectively different after Samyama compared to pre-Samyama
values. Moreover, to avoid false positive findings, we used a
conservative statistical approach with stringent corrections for
multiple comparisons, when we observed significant differences.
It was a functional study; therefore, to avoid misregistration, clear
instructions were given regarding the procedure and expected
patient experiences (e.g., MRI machine noise, commands to
follow and for what duration) and questions were answered.
The commands were given in the same way during the
image acquisition to reproduce highly specific and sensitive
information. Despite that, individual variations cannot be
eliminated regarding patient meditation inside the scanner versus
outside. Ear plugs were given during the fMRI scanning to blot
out the machine noise. However, its effect on the qualitative
measure of individual meditation could not be eliminated
(Travis et al., 2020). The images had minimal noise, thus
favoring an adequate imaging study, based on which these
inferences have been made.
Another limitation was the number of consenting controls.
Because of a small number of controls, they were age matched.
The average age of meditators was in the mid 30 s while
the average age of controls was in the 60 s. This is a
significant consideration since functional connectivity has shown
to change with age (Betzel et al., 2014; Geerligs et al.,
2015). Therefore, findings from comparisons made between
the meditator and control groups should be approached with
some caution. To minimize potential differences due to other
factors such as age, we used controls and meditators their
own controls as we did fMRI scans before and after the
Samyama program. It is important to note that the MRI
scans were obtained before and after Samyama program
3 years ago. At this point, we are unable to re-create the
conditions to obtain suitable controls in terms of timing
of scans similar to meditators and artifacts associated with
harmonization of fMRI even if we were to use the same
MRI machines and protocols. Despite these limitations, this
study provides novel insight into brain mechanisms before
and after Samyama program during the resting state and
focused breath watching and demonstrates correlations with
improved mindfulness after Samyama. Future studies using a
larger sample size and proper age-matched controls can further
investigate functional connectivity changes in different regions
during resting states and meditative practices, in addition to
correlating with other psychological improvements associated
with advanced meditation.
Frontiers in Psychology | www.frontiersin.org
CONCLUSION
Samyama, an 8-day intensive meditation program, favorably
influenced the functional connectivity between the salience
and default mode networks on meditators compared to their
baseline and non-meditator controls. Furthermore, specific brain
functional connectivity changes were different at resting state
and meditation-related focused breath watching in meditators.
This study was also able to correlate changes in functional
connectivity to improved mindfulness scores in meditators.
Results are consistent with existing literature regarding the
observed changes in functional connectivity of the anterior
cingulate cortex from meditative processes. Studies with larger
sample sizes can further investigate functional connectivity
changes in different regions during resting states and meditative
practices, in addition to correlating with longer-term and
other psychological improvements associated with advanced
meditative practices.
DATA AVAILABILITY STATEMENT
The datasets presented in this article are not readily available
because this is a subset of a larger study group and further analysis
is currently planned. Raw data will be shared after the analysis is
complete. Requests to access the datasets should be directed to SS
at ssenthil@pitt.edu.
ETHICS STATEMENT
The studies involving human participants were reviewed and
approved by this study was reviewed and approved by the Indiana
University School of Medicine Institutional Review Board. All
subjects provided written or electronic consent to participate. The
patients/participants provided their written informed consent to
participate in this study.
AUTHOR CONTRIBUTIONS
RV and RR contributed to the study design, data analysis and
interpretation, and manuscript drafting and editing. KK and
RD contributed to the data analysis. CR and BS contributed to
the study design and manuscript preparation. JR contributed
to the manuscript drafting and editing. DP contributed to the
research coordination, IRB approval and communications, study
conduct, and data collection. SS contributed to the study design,
conduct, data collection, coordination, manuscript preparation,
and arranging funding for this study. All authors have approved
the submitted version and have agreed both to be personally
accountable for the author’s own contributions and to ensure
that questions related to the accuracy and integrity of any
part of the work, even ones in which the author was not
personally involved, are appropriately investigated, resolved, and
the resolution documented in the literature.
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Meditation Alters Network Functional Connectivity
FUNDING
ACKNOWLEDGMENTS
This study was entirely funded by the Department of Anesthesia,
Indiana University School of Medicine, including salary support
for the medical writer, statistician, and research coordinator. No
external funding was used for this research.
The authors appreciate support provided by Isha
Institute of Inner Sciences, McMinnville, TN and study
volunteers for this prospective research on Samyama
participants.
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