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Large-Scale Functional Brain Network Reorganization During Taoist Meditation

Abstract

Meditation induces a distinct and reversible mental state that provides insights into brain correlates of consciousness. We explored brain network changes related to meditation by graph theoretical analysis of resting-state functional magnetic resonance imaging (rs-fMRI) data. Eighteen Taoist meditators with varying levels of expertise were scanned using a within-subjects counterbalanced design during resting and meditation states. State-related differences in network topology were measured globally and at the level of individual nodes and edges. Although measures of global network topology, such as small-worldness, were unchanged, meditation was characterized by an extensive and expertise-dependent reorganization of the hubs (highly connected nodes) and edges (functional connections). Areas of sensory cortex, especially the bilateral primary visual and auditory cortices, and the bilateral temporopolar areas, which had the highest degree (or connectivity) during the resting state, showed the biggest decrease during meditation. Conversely, bilateral thalamus and components of the default mode network (DMN), mainly the bilateral precuneus and posterior cingulate cortex, had low degree in the resting state but increased degree during meditation. Additionally, these changes in nodal degree were accompanied by reorganization of anatomical orientation of the edges. During meditation, long-distance longitudinal (antero-posterior) edges increased proportionally whereas orthogonal long-distance transverse (right-left) edges connecting bilaterally homologous cortices decreased. Our findings suggest that transient changes in consciousness associated with meditation introduce convergent changes in the topological and spatial properties of brain functional networks, and the anatomical pattern of integration might be as important as the global level of integration when considering the network basis for human consciousness.
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... In a study with Alzheimer's patients, Haan et al. [14] observed more randomness than the small-word structure on FBN and this topological difference was linked to low efficient information exchange among brain regions. Taoist meditation changes topological and spatial properties of FBN [15]. The time of meditation experience increases functional connectivity of the brain regions that are in charge to cognitive functions, as attention. ...
... Using fMRI, Jao et al. [15] analysed the cerebral network differences between MD and RS. They used graphs theory to construct the FBN of 18 Taoist meditators with different levels of experience. ...
... First, the small sample size hinders the ability of more robust conclusions. Nonetheless, other studies in this area had similarly 12 T. G. TOUTAIN ET AL. small samples [15] but presented important findings for the study of complex brain networks. Lack of a control group prevents discussion on how these time-dependent variables are characterized in individuals with none or little meditative experience. ...
Article
The dynamical approach represents a new branch in the understanding of functional brain networks. Using simple indices to represent time connectivity and topological stability, we evaluated the hypothesis of increased brain stability during the meditative state in comparison to the relaxation state. We used a new way to consider the time evolution of synchronization patterns in electroencephalography (EEG) data. The time-varying graph approach and the motif synchronization method were combined to build a set of graphs representing time evolution for the synchronization of 29 EEG electrodes. We analysed these graphs during meditation and relaxation states in 17 experienced meditators. As result, we found significant increasing of time connectivity (t(15) $= -2.50$, p $= 0.023$) and topological stability (t(15) $= 1.23$, p $= 0.020$) in the meditation state when compared to the relaxation state. These findings suggest that dynamical properties of the synchronization network may revel aspects of brain activity in altered states of consciousness not possible to measure using a static approach. We concluded that the topological patterns evolution in the functional networks of experienced meditators are more stable in the meditative state than in the relaxation state.
... In this context, we have previously observed that experienced mindfulness meditators showed long-lasting topological changes in the right hippocampus during resting state condition, suggesting that MM might also have functional effects on prospective and spatial memory [26]. Furthermore, a study comparing meditation phase and resting state in expert meditators showed increased nodal degree of thalamus, posterior cingulate cortex, precuneus, medial prefrontal cortex, inferior parietal lobule, and dorsolateral prefrontal cortex, during the meditative phase [27]. ...
Article
We have previously evidenced that Mindfulness Meditation (MM) in experienced meditators (EMs) is associated with long-lasting topological changes in resting state condition. However, what occurs during the meditative phase is still debated. Utilizing magnetoencephalography (MEG), the present study is aimed at comparing the topological features of the brain network in a group of EMs (n = 26) during the meditative phase with those of individuals who had no previous experience of any type of meditation (NM group, n = 29). A wide range of topological changes in the EM group as compared to the NM group has been shown. Specifically, in EMs, we have observed increased betweenness centrality in delta, alpha, and beta bands in both cortical (left medial orbital cortex, left postcentral area, and right visual primary cortex) and subcortical (left caudate nucleus and thalamus) areas. Furthermore, the degree in beta band in parietal and occipital areas of EMs was increased too. Our exploratory study suggests that the MM can change the functional brain network and provides an explanatory hypothesis on the brain circuits characterizing the meditative process.
... Multiple experiments have shown that the DMN, SN, and CEN are associated with mindfulness [100][101][102] and interact with each other [100,103]. During the active state of meditation, the between-network connectivity of the DMN, CEN and SN is increased [104,105]. Our results imply that the precuneus may be involved in three networks and relate to the between-network connectivity of the DMN, CEN and SN after visual restoration, but the relevant mechanism is not clear. ...
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Background Pituitary adenoma (PA) may compress the optic apparatus, resulting in impaired vision. Some patients can experience improved vision rapidly after surgery. During the early period after surgery, however, the change in neurofunction in the extravisual cortex and higher cognitive cortex has yet to be explored. Objective Our study focused on the changes in the extravisual resting-state networks in patients with PA after vision restoration. Methods We recruited 14 patients with PA who experienced visual improvement after surgery. The functional connectivity (FC) of 6 seeds [auditory cortex (A1), Broca’s area, posterior cingulate cortex (PCC) for the default mode network (DMN), right caudal anterior cingulate cortex for the salience network (SN) and left dorsolateral prefrontal cortex for the executive control network (ECN)] were evaluated. A paired t test was conducted to identify the differences between two groups of patients. Results Compared with their preoperative counterparts, patients with PA with improved vision exhibited decreased FC with the right A1 in the left insula lobule, right middle temporal gyrus and left postcentral gyrus and increased FC in the right paracentral lobule; decreased FC with the Broca in the left middle temporal gyrus and increased FC in the left insula lobule and right thalamus; decreased FC with the DMN in the right declive and right precuneus; increased FC in right Brodmann area 17, the left cuneus and the right posterior cingulate; decreased FC with the ECN in the right posterior cingulate, right angular and right precuneus; decreased FC with the SN in the right middle temporal gyrus, right hippocampus, and right precuneus; and increased FC in the right fusiform gyrus, the left lingual gyrus and right Brodmann area 19. Conclusions Vision restoration may cause a response of cross-modal plasticity and multisensory systems related to A1 and the Broca. The DMN and SN may be involved in top-down control of the subareas within the visual cortex. The precuneus may be involved in the DMN, ECN and SN simultaneously.
... Two studies correlated fMRI measures of brain function with measures of subjective experience, assessed either during the fMRI scan (Kim et al., 2019) or post-scanning (Hernandez et al., 2018). Two studies used subjective indications when participants were entering meditative states to guide fMRI data analysis (Jao et al., 2016;Modestino, 2016). In two other studies, indications of subjective experience during the entire fMRI scan were part of the study design. ...
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Objectives As meditation is increasingly employed for the promotion of good health, there is a growing interest in using neuroimaging methods to investigate the neural mechanisms by which meditation acts. In the wake of this rising interest, criticism regarding the lack of clarity concerning theory, definitions, and taxonomy, as well as deficient or poorly reported methodology, has arisen. The aim of this study was to investigate trends in current neuroimaging research on meditation and to provide guidelines for future studies. Methods We made a literature search for articles published during 2016–2019 using the search phrases “meditation” and “functional magnetic resonance imaging or fMRI”. Inclusion criteria were limited to meditation studies using resting-state fMRI or such task-based fMRI examinations that were specifically targeting meditative states in healthy participants. Text analysis was performed using Nvivo 12 Mac (QSR International). Results Twenty-eight articles were included from which we identified four different intention-based dimensions of meditation practice: The present moment, Wholesome qualities to cultivate, Unwholesome qualities to avoid, and Attitudes. Half of the studies do not make assessments of subjective experience. The results were related to networks and brain regions describing cognitive, affective, somatic, and self domains of brain function. Most studies describe meditation-related brain function in terms of “processes”. Conclusions We defined five areas of potential improvement regarding research methodology: (1) Provide clear and unambiguous definitions of constructs and practices, (2) Include measures of subjective experience, (3) Perform correct assessment of processes, (4) Combine methodologies for more substantiated conclusions, (5) Avoid the risk of overinterpretation.
... Herein, we chose a longitudinal study (to remove the effect of baseline rsFC) to investigate the feasibility and sensitivity of dASL in detecting the effects of meditation on rsFC and CBF. Considering the regulatory role of frontoparietal control network (FPN) in the attention control in response to salient stimuli [31,32] and consistent finding for inter-network connections among DMN, FPN, and salience network (SN) during active meditation state [33][34][35][36], we anticipated that dASL is capable of detecting rsFC with FPN and SN from DMN and DAN seeds. Given that there are many different forms of meditation, such as focused attention or open monitoring or non-dual awareness, we studied one specific type of meditation-focused attention meditation (FAM)-in the study to avoid potentially canceling effects from different meditation categories. ...
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We aimed to assess whether dynamic arterial spin labeling (dASL), a novel quantitative MRI technique with minimal contamination of subject motion and physiological noises, could detect the longitudinal effect of focused attention meditation (FAM) on resting-state functional connectivity (rsFC). A total of 10 novice meditators who recorded their FAM practice time were scanned at baseline and at the 2-month follow-up. Two-month meditation practice caused significantly increased rsFC between the left medial temporal (LMT) seed and precuneus area and between the right frontal eye (RFE) seed and medial prefrontal cortex. Meditation practice time was found to be positively associated with longitudinal changes of rsFC between the default mode network (DMN) and dorsal attention network (DAN), between DMN and insula, and between DAN and the frontoparietal control network (FPN) but negatively associated with changes of rsFC between DMN and FPN, and between DAN and visual regions. These findings demonstrate the capability of dASL in identifying the FAM-induced rsFC changes and suggest that the practice of FAM can strengthen the efficient control of FPN on fast switching between DMN and DAN and enhance the utilization of attentional resources with reduced focus on visual processing.
... Eight studies compared meditation to a passive control condition (rest). Of those eight studies, four investigated long-term meditators (no control group) and observed a higher activity in the ACC (Mahone et al., 2018), a stronger connectivity between the rACC and the insula/putamen (Hernández et al., 2018), a stronger connectivity between the PCC and the medial prefrontal cortex among other regions (Jao et al., 2016), and a weaker functional connectivity between the PCC and the striatum (Fujino et al., 2018) during meditation. Two studies focused on meditation beginners (no control group) and observed a higher activity in the ACC (Kalyani et al., 2011) as well as a weaker connectivity between the ACC and the amygdala (Rao et al., 2018) during meditation. ...
Article
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Objectives Neuroimaging-based research has revealed varying effects of meditation/mindfulness in sections of the cingulate cortex. However, a formal review of this literature is currently missing.Methods PubMed and APA PsycINFO databases were searched to identify studies based on functional magnetic resonance imaging (fMRI), resting-state fMRI (rs-fMRI), structural MRI (sMRI), and diffusion tensor imaging (DTI) that reported effects (or explicitly stated null effects) of meditation/mindfulness in the cingulate.ResultsOf the 49 studies published over the last two decades, the majority were cross-sectional in nature (69%) and employed fMRI (61%). Most studies reported significant effects in the anterior cingulate cortex (55%), followed by the posterior cingulate cortex (49%) and the midcingulate cortex (20%). However, the nature of findings was extremely heterogeneous across studies, possibly due to a substantial variability in terms of study designs, sample sizes, demographics, meditation styles, cingulate subdivisions, and nomenclatures, just to name a few.Conclusions Altogether, the outcomes of this review suggest a multifaceted role of the cingulate for processes related to long-term meditation practices, short-term meditation trainings, as well as trait mindfulness.
... Some studies showed that the SN play a role in the dynamic switching of antagonistic activity between the DMN and CEN in cognitively normal young brains [98,99,91].Multiple experiments have shown that DMN, SN, and CEN is respectively associated with mindfulness [100,101,102], and also interact with each other [100,103]. During the active state of meditation, between-network connectivity of DMN, CEN and SN are increased [104,105]. Our results imply that precuneus may involve in three networks and relate to between-network connectivity of DMN, CEN and SN after visual restoration, but the mechanism is not clear. ...
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Background: Pituitary adenoma(PA) may compress the optic apparatus and cause impaired vision. Some patients can get improved vision rapidly after surgery. During the early time after surgery, however, the change of neurofunction in extra-visual cortex and higher cognitive cortex is still yet to be explored so far. Objective: Our study is focused on the changes in the extra-visual resting-state networks in PA patients after vision restoration. Methods:We recruited 14 PA patients with visual improvement after surgery. The functional connectivity (FC) of 6 seeds (auditory cortex (A1), Broca's area, posterior cingulate cortex (PCC)for default mode network (DMN), right caudal anterior cingulate cortex for salience network(SN) and left dorsolateral prefrontal cortex for excecutive control network (ECN)) were evaluated. A paired t-test was conducted to identify the differences between two groups. Results: Compared with the preoperation counterparts, the PA patients with improved vision exhibited decreased FC with right A1 was identified in left insula lobule, right middle temporal gyrus and left postcentral gyrus, and increased FC in the right paracentral lobule; decreased FC with broca in left middle temporal gyrus, and increased FC in left Insula lobule and right thalamus; decreased FC with DMN in right declive, and right precuneus, and increased FC in right brodmann area 17, left cuneus and right posterior cingulate; decreased FC with ECN in right posterior cingulate, right angular and right precuneus; decreased FC with SN in right middle temporal gyrus, right hippocampus, and right precuneus, and increased FC in right fusiform gyrus, left lingual gyrus and right brodmann area 19. Conclusions: The vision restoration may cause the response of cross-modal plasticity and the multisensory system related to A1 and broca. The DMN and SN may involve in top-down control on the subareas within vision cortex. The precuneus may involve in DMN, ECN and SN simultaneously.
... Studies have begun to examine emotional processes from a network perspective (Barrett & Satpute, 2013;Brandl et al., 2018;Hermans et al., 2011;McMenamin, Langeslag, Sirbu, Padmala, & Pessoa, 2014;Pessoa, 2017), but have yet to address how network properties change when a mindful acceptance or narrativeevaluative mindset is applied to emotional experience. Additionally, while numerous studies have examined network properties in relation to meditation training (Brewer, et al., 2011;Creswell et al., 2016;Farb, et al., 2013;Farb, et al., 2007;Jang et al., 2011;Jao et al., 2016;Josipovic, Dinstein, Weber, & Heeger, 2011;Pagnoni, 2012;Tang, Tang, Tang, & Lewis-Peacock, 2017;Taren et al., 2015;Xue, Tang, & Posner, 2011), few studies have specifically targeted emotional processes or compared network organization during different types of introspective states within the same individuals. ...
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Individuals use various strategies to cope with challenging emotions such as anxiety. Mindful acceptance involves broadening attentional scope and fully experiencing present moment sensory feelings (whether pleasant or unpleasant) without judgment or elaboration. In contrast, narrative-evaluation involves focusing on a narrow band of sensory experience and generating an elaborate narrative about the meaning and desirability of one's emotional feelings. The current study examined brain network organization during these strategies using graph theoretic analyses. We used a naturalistic task paradigm in which participants reflected on an anxiety-provoking issue from their personal lives and adopted each strategy in different blocks. Compared to narrative-evaluation, mindful acceptance was associated with: (i) increased global network connectivity; (ii) greater integration of interoceptive regions (mid and posterior insula) into large-scale networks; (iii) reorganization of motivational circuits including a shift in the striatum's network assignment from the default network to the salience network; and (iv) a shift from default network to frontoparietal control network (FPCN) regions as central hubs that coordinate information flow. Functional connectivity patterns within the left FPCN were associated with acceptance reports. Thus, broadening attentional scope during mindful acceptance is supported by a more globally interconnected neural landscape, as well as greater information flow through FPCN regions that underlie metacognitive awareness and cognitive control.
... In addition, brain scan studies of longterm meditators have shown distinctions in brain structure and function compared to non-meditators (Lazar et al., 2005;Engen et al., 2017). Furthermore, several studies of intense spiritual practices, including longitudinal ones, also reveal alterations in brain function including changes in frontal, parietal cortices (Newberg et al., 2010;Shao et al., 2016;Jao et al., 2016), as well as changes in dopaminergic and serotonergic levels . ...
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This article reviews the most recent information and data regarding brain processes associated with altered states of consciousness. It takes a neurotheological approach, seeking to blend what is known about these states, particularly as they relate to religious and spiritual experiences, in terms of brain processes and subjective elements of the experiences. The overall goal is to provide a comprehensive model that incorporates multiple brain areas including cortical, limbic, and subcortical structures, as well as considers the various neurotransmitters that might be involved. It is the hope that this framework provides a starting point for future investigations into the detailed neurophysiological and phenomenal aspects of altered states of consciousness.
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1. Introduction to wavelets 2. Review of Fourier theory and filters 3. Orthonormal transforms of time series 4. The discrete wavelet transform 5. The maximal overlap discrete wavelet transform 6. The discrete wavelet packet transform 7. Random variables and stochastic processes 8. The wavelet variance 9. Analysis and synthesis of long memory processes 10. Wavelet-based signal estimation 11. Wavelet analysis of finite energy signals Appendix. Answers to embedded exercises References Author index Subject index.
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