Shifting brain asymmetry: the link between meditation and structural lateralization

Neuromodulation and meditation: A review and synthesis toward promoting well-being and understanding consciousness and brain

The neuroscience of meditation is providing insight into meditation's beneficial effects on well-being and informing understanding of consciousness. However, further research is needed to explicate mechanisms linking brain activity and meditation. Non-invasive brain stimulation (NIBS) presents a promising approach for causally investigating neural mechanisms of meditation. Prior NIBS-meditation research has predominantly targeted frontal and parietal cortices suggesting that it might be possible to boost the behavioral and neural effects of meditation with NIBS. Moreover, NIBS has revealed distinct neural signatures in long-term meditators. Nonetheless, methodological variations in NIBS-meditation research contributes to challenges for definitive interpretation of previous results. Future NIBS studies should further investigate core substrates of meditation, including specific brain networks and oscillations, and causal neural mechanisms of advanced meditation. Overall, NIBS-meditation research holds promise for enhancing meditation-based interventions in support of well-being and resilience in both non-clinical and clinical populations, and for uncovering the brain-mind mechanisms of meditation and consciousness.

Daily breath-based mindfulness exercises in a randomized controlled trial improve primary school children's performance in arithmetic

Mindfulness-based interventions (MBIs) have been shown to improve children's academic achievements. Because MBIs include different exercises (possibly with differential effects), the teacher-led Breathing Break Intervention (BBI) was developed which focuses exclusively on breathing exercises and body awareness. The short daily breathing practices of BBI were evaluated in terms of their effects on children's performance in mathematics. In a randomized controlled trial, N = 140 third and fourth graders (49% female) either received BBI (IG, n = 81) or participated in an active control group (ACG, n = 59). Students took a standardized arithmetic test and teachers rated their mathematics performance before (T1) and after (T2) the nine weeks of BBI, and in a follow-up five months later (T3). A mixed multilevel model with a quadratic term of time indicated a significant interaction effect between group and time on the arithmetic test after controlling for working memory updating and parental educational attainment. IG children did not show a steeper linear increase but differed significantly from ACG children in their trajectory of arithmetic performance. At T3, IG children outperformed ACG children. A multilevel ordinal logistic regression of teachers' ratings of students' mathematics performance revealed no significant differences between IG and ACG. Results suggest that daily breathing exercises in primary school classrooms contribute to enhancing children's performance in arithmetic.Preregistration: The study was preregistered at aspredicted.org (#44925).

Neuroanatomical correlates of cognitive impairment following basal ganglia-thalamic post-hemorrhagic stroke: Uncovering network-wide alterations in hemispheric gray matter asymmetry

Cognitive impairment and recovery are central issues in hemorrhagic stroke. This study aimed to investigate whether post-hemorrhagic stroke cognitive impairment (PhSCI) is associated with cortical gray matter (GM) loss and hemispheric asymmetry changes and whether these changes could predict improvements in cognitive function during the recovery. Nineteen patients with PhSCI, comprising 10 with basal ganglia hemorrhage and 9 with thalamic hemorrhage, were recruited. Among them, 9 completed a course of repetitive transcranial magnetic stimulation (rTMS). Additionally, 19 demographically and comorbidity-matched healthy controls were also included. Structural brain MRI and cognitive assessments were performed. Voxel-wise GM volume and hemispheric asymmetry were analyzed. The PhSCI patients exhibited bilateral, yet asymmetric, GM losses in the hippocampus, fusiform, lateral temporal, prefrontal, somatomotor, and inferior parietal regions. The analysis of GM asymmetry revealed that patients showed rightward GM in the lateral temporal, somatomotor, and inferior parietal regions. Among the 9 PhSCI patients who completed rTMS, there was a marginal trend of regional GM increase and leftward GM, and these changes were in parallel with the improvements in cognitive tests. Further lesion connectivity and metanalytic mapping identified two interconnected systems linked to the lesions, which were anchored in the default mode, somatomotor, and salience/cognitive control networks and in the cognitive domains of memory, language, decision-making, and executive function. In conclusion, PhSCI patients exhibited network-wide cortical GM losses, distal to subcortical hemorrhagic lesions, and hemisphere asymmetry changes. These changes appear to predict rTMS-related cognitive improvements, suggesting that even subcortical focal lesions can lead to alterations in distal cortical neuroanatomical architecture. Our preliminary findings provide new insights into the neuroanatomical basis of PhSCI.

How Does Meditation Affect the Default Mode Network: A Systematic Review

This article provides a systematic review of studies evaluating the effect of meditation on the Default Mode Network (DMN). The review was conducted according to PRISMA guidelines. A literature search of PubMed, Scopus, and Embase was conducted up to June 2020. Search terms included default mode network or DMN and meditation.A total of 306 articles were identified, of which 16 controlled trials with a total of 853 experienced (in Mindfulness, Samatha, Raja Yoga, Transcendental Meditation, Vipassana, Insight meditation Theravada tradition) and non-experienced mediators were finally included in this systematic review. The results showed that meditative interventions affect the operation of DMN and there are differences in functional connectivity between networks. Further research should be undertaken to establish meditation as an effective intervention strategy for well-being.

Taking Sides: Asymmetries in the Evolution of Human Brain Development in Better Understanding Autism Spectrum Disorder

Confirmation from structural, functional, and behavioral studies agree and suggest a configuration of atypical lateralization in individuals with autistic spectrum disorders (ASD). It is suggested that patterns of cortical and behavioral atypicality are evident in individuals with ASDs with atypical lateralization being common in individuals with ASDs. The paper endeavors to better understand the relationship between alterations in typical cortical asymmetries and functional lateralization in ASD in evolutionary terms. We have proposed that both early genetic and/or environmental influences can alter the developmental process of cortical lateralization. There invariably is a “chicken or egg” issue that arises whether atypical cortical anatomy associated with abnormal function, or alternatively whether functional atypicality generates abnormal structure.

Open monitoring meditation alters the EEG gamma coherence in experts meditators: The expert practice exhibit greater right intra-hemispheric functional coupling

AIM

This study investigated the differences in frontoparietal EEG gamma coherence between expert meditators (EM) and naïve meditators (NM).

MATERIAL AND METHODS

This is a cross-sectional study with a sample of twenty-one healthy adults divided under two groups (experts meditators vs. naive-meditators), with analyzing the intra-hemispheric coherence of frontoparietal gamma oscillations by electroencephalography during the study steps: EEG resting-state 1, during the open presence meditation practice, and EEG resting-state 2.

RESULTS

The findings demonstrated greater frontoparietal EEG coherence in gamma for experts meditators in the Fp1-P3, F4-P4, F8-P4 electrode pairs during rest 1 and rest 2 (p ≤ 0.0083). In addition, we evidenced differences in the frontoparietal EEG coherence for expert meditators in F4-P4, F8-P4 during the meditation (p ≤ 0.0083).

CONCLUSION

Our results can support evidence that the connectivity of the right frontoparietal network acts as a biomarker of the enhanced Open monitoring meditation training.

Enhanced Resting-State Functional Connectivity With Decreased Amplitude of Low-Frequency Fluctuations of the Salience Network in Mindfulness Novices

Mindfulness and accordant interventions are often used as complementary treatments to psychological or psychosomatic problems. This has also been gradually integrated into daily lives for the promotion of psychological well-being in non-clinical populations. The experience of mindful acceptance in a non-judgmental way brought about the state, which was less interfered by a negative effect. Mindfulness practice often begins with focused attention (FA) meditation restricted to an inner experience. We postulate that the brain areas related to an interoceptive function would demonstrate an intrinsic functional change after mindfulness training for the mindful novices along with paying more attention to internal processes. To further explore the influence of mindfulness on the organization of the brain regions, both functional connectivity (FC) in the voxel and the region of interest (ROI) level were calculated. In the current study, 32 healthy volunteers, without any meditation experiences, were enrolled and randomly assigned to a mindfulness-based stress reduction group (MBSR) or control group (CON). Participants in the MBSR group completed 8 weeks of mindfulness-based stress reduction (MBSR) and rated their mindfulness skills before and after MBSR. All subjects were evaluated via resting-state functional MRI (rs-fMRI) in both baselines and after 8 weeks. They also completed a self-report measure of their state and trait anxiety as well as a positive and negative affect. Pre- and post-MBSR assessments revealed a decreased amplitude of low-frequency fluctuations (ALFF) in the right anterior cingulate gyrus (ACC.R), left anterior and posterior insula (aIC.L, pIC.L), as well as left superior medial frontal gyrus (SFGmed.L) in MBSR practitioners. Strengthened FC between right anterior cingulate cortex (ACC.R) and aIC.R was observed. The mean ALFF values of those regions were inversely and positively linked to newly acquired mindful abilities. Along with a decreased negative affect score, our results suggest that the brain regions related to attention and interoceptive function were involved at the beginning of mindfulness. This study provides new clues in elucidating the time of evaluating the brain mechanisms of mindfulness novices.

Gray matter asymmetry in asymptomatic carotid stenosis

Even clinically “asymptomatic” carotid stenosis is associated with multidomain cognitive impairment, gray matter (GM) atrophy, and silent lesion. However, the links between them remain unclear. Using structural MRI data, we examined GM asymmetry index (AI) and white matter hyperintensity (WMH) in 24 patients with severe asymptomatic carotid stenosis (SACS), 24 comorbidity‐matched controls, and independent samples of 84 elderly controls and 22 young adults. As compared to controls, SACS patients showed worse verbal memories, higher WMH burden, and right‐lateralized GM in posterior middle temporal and mouth‐somatomotor regions. These clusters extended to pars triangularis, lateral temporal, and cerebellar regions, when compared with young adults. Further, a full‐path of WMH burden (X), GM volume (atrophy, M1), AI (asymmetry, M2), and neuropsychological variables (Y) through a serial mediation model was analyzed. This analysis identified that left‐dominated GM atrophy and right‐lateralized asymmetry in the posterior middle temporal cortex mediated the relationship between WMH burden and recall memory in SACS patients. These results suggest that the unbalanced hemispheric atrophy in the posterior middle temporal cortex is crucial to mediating relationship between WMH burden and verbal recall memories, which may underlie accelerated aging and cognitive deterioration in patients with SACS and other vascular cognitive impairment.

Reduced age-related gray matter loss in the subgenual cingulate cortex in long-term meditators

Accumulating evidence suggests that meditation practices have positive effects on brain ageing overall. The cingulate is known to be recruited during meditation, but research into possible effects of meditation on the ageing of the cingulate is currently missing. Thus, the present study was designed to help close this knowledge gap, with particular focus on the subgenual cingulate, a region involved in emotional regulation and autonomic and endocrine functions, making it potentially relevant for meditation. Here, we investigated differences in age-related gray matter loss between 50 long-term meditation practitioners (28 male, 22 female), aged between 24 and 77, and 50 age- and sex-matched controls. Areas of interest were four subregions of the subgenual cingulate gyrus (areas 25, 33, s24, and s32) defined as per the Julich-Brain atlas. Our study revealed a significant age-related decline in all subregions in both meditators and controls, but with significantly lower rates of annual tissue loss in meditators, specifically in left and right area s32 and right area 25. These regions have been shown to play a role in mood regulation, autonomic processing, and the integration of emotion and cognitive processes, which are all involved in and impacted by meditation. Overall, the results add further evidence to the emerging notion that meditation may slow the effects of ageing on the brain.

Neuroplasticity within and between Functional Brain Networks in Mental Training Based on Long-Term Meditation

(1) The effects of intensive mental training based on meditation on the functional and structural organization of the human brain have been addressed by several neuroscientific studies. However, how large-scale connectivity patterns are affected by long-term practice of the main forms of meditation, Focused Attention (FA) and Open Monitoring (OM), as well as by aging, has not yet been elucidated. (2) Using functional Magnetic Resonance Imaging (fMRI) and multivariate pattern analysis, we investigated the impact of meditation expertise and age on functional connectivity patterns in large-scale brain networks during different meditation styles in long-term meditators. (3) The results show that fMRI connectivity patterns in multiple key brain networks can differentially predict the meditation expertise and age of long-term meditators. Expertise-predictive patterns are differently affected by FA and OM, while age-predictive patterns are not influenced by the meditation form. The FA meditation connectivity pattern modulated by expertise included nodes and connections implicated in focusing, sustaining and monitoring attention, while OM patterns included nodes associated with cognitive control and emotion regulation. (4) The study highlights a long-term effect of meditation practice on multivariate patterns of functional brain connectivity and suggests that meditation expertise is associated with specific neuroplastic changes in connectivity patterns within and between multiple brain networks.

Atypical Brain Asymmetry in Autism-A Candidate for Clinically Meaningful Stratification

BACKGROUND

Autism spectrum disorder ("autism") is a highly heterogeneous neurodevelopmental condition with few effective treatments for core and associated features. To make progress we need to both identify and validate neural markers that help to parse heterogeneity to tailor therapies to specific neurobiological profiles. Atypical hemispheric lateralization is a stable feature across studies in autism, but its potential as a neural stratification marker has not been widely examined.

METHODS

In order to dissect heterogeneity in lateralization in autism, we used the large EU-AIMS (European Autism Interventions-A Multicentre Study for Developing New Medications) Longitudinal European Autism Project dataset comprising 352 individuals with autism and 233 neurotypical control subjects as well as a replication dataset from ABIDE (Autism Brain Imaging Data Exchange) (513 individuals with autism, 691 neurotypical subjects) using a promising approach that moves beyond mean group comparisons. We derived gray matter voxelwise laterality values for each subject and modeled individual deviations from the normative pattern of brain laterality across age using normative modeling.

RESULTS

Individuals with autism had highly individualized patterns of both extreme right- and leftward deviations, particularly in language, motor, and visuospatial regions, associated with symptom severity. Language delay explained most variance in extreme rightward patterns, whereas core autism symptom severity explained most variance in extreme leftward patterns. Follow-up analyses showed that a stepwise pattern emerged, with individuals with autism with language delay showing more pronounced rightward deviations than individuals with autism without language delay.

CONCLUSIONS

Our analyses corroborate the need for novel (dimensional) approaches to delineate the heterogeneous neuroanatomy in autism and indicate that atypical lateralization may constitute a neurophenotype for clinically meaningful stratification in autism.

Attentional and cognitive monitoring brain networks in long-term meditators depend on meditation states and expertise

Meditation practice is suggested to engage training of cognitive control systems in the brain. To evaluate the functional involvement of attentional and cognitive monitoring processes during meditation, the present study analysed the electroencephalographic synchronization of fronto-parietal (FP) and medial-frontal (MF) brain networks in highly experienced meditators during different meditation states (focused attention, open monitoring and loving kindness meditation). The aim was to assess whether and how the connectivity patterns of FP and MF networks are modulated by meditation style and expertise. Compared to novice meditators, (1) highly experienced meditators exhibited a strong theta synchronization of both FP and MF networks in left parietal regions in all mediation styles, and (2) only the connectivity of lateralized beta MF networks differentiated meditation styles. The connectivity of intra-hemispheric theta FP networks depended non-linearly on meditation expertise, with opposite expertise-dependent patterns found in the left and the right hemisphere. In contrast, inter-hemispheric FP connectivity in faster frequency bands (fast alpha and beta) increased linearly as a function of expertise. The results confirm that executive control systems play a major role in maintaining states of meditation. The distinctive lateralized involvement of FP and MF networks appears to represent a major functional mechanism that supports both generic and style-specific meditation states. The observed expertise-dependent effects suggest that functional plasticity within executive control networks may underpin the emergence of unique meditation states in expert meditators.

Mindfulness related changes in grey matter: a systematic review and meta-analysis

Knowing target regions undergoing strfuncti changes caused by behavioural interventions is paramount in evaluating the effectiveness of such practices. Here, using a systematic review approach, we identified 25 peer-reviewed magnetic resonance imaging (MRI) studies demonstrating grey matter changes related to mindfulness meditation. An activation likelihood estimation (ALE) analysis (n = 16) revealed the right anterior ventral insula as the only significant region with consistent effect across studies, whilst an additional functional connectivity analysis indicates that both left and right insulae, and the anterior cingulate gyrus with adjacent paracingulate gyri should also be considered in future studies. Statistical meta-analyses suggest medium to strong effect sizes from Cohen’s d ~ 0.8 in the right insula to ~ 1 using maxima across the whole brain. The systematic review revealed design issues with selection, information, attrition and confirmation biases, in addition to weak statistical power. In conclusion, our analyses show that mindfulness meditation practice does induce grey matter changes but also that improvements in methodology are needed to establish mindfulness as a therapeutic intervention.

Changes in Gray Matter Asymmetries of the Fusiform and Parahippocampal Gyruses in Patients With Subcortical Ischemic Vascular Disease

Objective: Changes in the normal asymmetry of the human brain often mean pathology. Current studies on the correlation between asymmetry and cognitive impairment have focused on Alzheimer's disease (AD) and AD-related mild cognitive impairment (MCI). The purpose of this study was to investigate changes in gray matter asymmetry and their relationship with cognitive impairment in patients with subcortical ischemic vascular disease (SIVD) by using voxel-based morphological measurements. Methods: Fifty-nine SIVD patients with (subcortical vascular cognitive impairment, SVCI, N = 30) and without (pre-SVCI, N = 29) cognitive impairment and 30 normal controls (NC, N = 30) underwent high-resolution structural MRI and neuropsychological examinations. The differences in gray matter asymmetry among the three groups were estimated by using one-way ANOVA. Moreover, partial correlation analysis was performed to explore the relationships between the asymmetry index (AI) values and cognitive assessments controlled for age, sex, and education. Results: The gray matter asymmetries in the fusiform and parahippocampal gyruses of the SVCI group were significantly different from those of the NC group and the pre-SVCI group, while no differences were found between the NC group and the pre-SVCI group in the same areas. More specifically, in the fusiform and parahippocampal gyruses, the SVCI group displayed a dramatic rightward asymmetry, whereas the NC group and pre-SVCI group exhibited a marked leftward asymmetry. The results of the correlation analysis showed that the "mean AI" in significant cluster was strongly correlated with the changes in cognitive outcomes. Conclusion: This study demonstrated different lateralization in the fusiform and parahippocampal gyruses of SIVD patients with cognitive impairment compared to healthy subjects and SIVD patients without cognitive decline. Our findings may contribute to better understanding the possible mechanism of cognitive impairment in patients with SIVD, and they suggest the possibility of using gray matter asymmetry as a biomarker for disease progression.

Cortical reorganization processes in meditation naïve participants induced by 7 weeks focused attention meditation training

BACKGROUND

Based on the evidence that meditation is associated with numerous beneficial effects on well-being and reduced stress-related symptoms, mindfulness-based techniques were increasingly implemented into psychotherapeutic programs. However, different meditation styles and the cross-sectional nature of most previous analyses resulted in a great variety of morphometric findings. The present study aims to elucidate cortical reorganization processes and altered axonal integrity caused by short-term meditation training, and benefits from solely using focused attention meditation (FAM).

METHODS

3 T MRI, including T1-MPRAGE and diffusion-weighted sequences, was performed in 27 healthy, meditation naïve participants (age: 43 ± 12.4 years) pre and post FAM meditation training (duration: 7.3 ± 0.4 weeks). Voxel-based morphometry was applied to assess brain changes in gray and white matter. Questionnaires were filled out by the individuals at both time-points to evaluate quality of life and self-awareness deficits.

RESULTS

The major findings comprised (i) gray matter increases in the insula, the caudate nucleus and frontal cortices, (ii) decreases in extended parietotemporal regions, the right medial prefrontal cortex and the parahippocampal gyrus, as well as (iii) fractional anisotropy increases of the right hippocampus, the basal ganglia and adjacent regions. Regression analysis revealed an association of specific alterations with reduced levels of state anxiety.

CONCLUSIONS

FAM training induced a broad range of dynamic brain alterations even within few weeks of training. Interestingly, this cohort revealed more, and partially different patterns of structural gray matter change compared to prior studies. The broad impact on neuronal organization processes may reflect more general outcomes related to health and well-being.

Rajyoga meditation induces grey matter volume changes in regions that process reward and happiness

Studies provide evidence that practicing meditation enhances neural plasticity in reward processing areas of brain. No studies till date, provide evidence of such changes in Rajyoga meditation (RM) practitioners. The present study aimed to identify grey matter volume (GMV) changes in reward processing areas of brain and its association with happiness scores in RM practitioners compared to non-meditators. Structural MRI of selected participants matched for age, gender and handedness (n = 40/group) were analyzed using voxel-based morphometric method and Oxford Happiness Questionnaire (OHQ) scores were correlated. Significant increase in OHQ happiness scores were observed in RM practitioners compared to non-meditators. Whereas, a trend towards significance was observed in more experienced RM practitioners, on correlating OHQ scores with hours of meditation experience. Additionally, in RM practitioners, higher GMV were observed in reward processing centers—right superior frontal gyrus, left inferior orbitofrontal cortex (OFC) and bilateral precuneus. Multiple regression analysis showed significant association between OHQ scores of RM practitioners and reward processing regions right superior frontal gyrus, left middle OFC, right insula and left anterior cingulate cortex. Further, with increasing hours of RM practice, a significant positive association was observed in bilateral ventral pallidum. These findings indicate that RM practice enhances GMV in reward processing regions associated with happiness.

Common and distinct lateralised patterns of neural coupling during focused attention, open monitoring and loving kindness meditation

Meditation has been integrated into different therapeutic interventions. To inform the evidence-based selection of specific meditation types it is crucial to understand the neural processes associated with different meditation practices. Here we explore commonalities and differences in electroencephalographic oscillatory spatial synchronisation patterns across three important meditation types. Highly experienced meditators engaged in focused attention, open monitoring, and loving kindness meditation. Improving on previous research, our approach avoids comparisons between groups that limited previous findings, while ensuring that the meditation states are reliably established. Employing a novel measure of neural coupling – the imaginary part of EEG coherence – the study revealed that all meditation conditions displayed a common connectivity pattern that is characterised by increased connectivity of (a) broadly distributed delta networks, (b) left-hemispheric theta networks with a local integrating posterior focus, and (c) right-hemispheric alpha networks, with a local integrating parieto-occipital focus. Furthermore, each meditation state also expressed specific synchronisation patterns differentially recruiting left- or right-lateralised beta networks. These observations provide evidence that in addition to global patterns, frequency-specific inter-hemispheric asymmetry is one major feature of meditation, and that mental processes specific to each meditation type are also supported by lateralised networks from fast-frequency bands.

Frontal alpha asymmetry during prayerful and resting states: An EEG study in Catholic sisters

INTRODUCTION

Life expectancy in the US is 78.6 years, and although people are living longer, they are also living with chronic diseases. As women age, they are more susceptible to chronic disease including mental health conditions and Alzheimer's Disease (AD) dementia. Therefore, practical and cost effective ways to prevent the onset of cognitive, mental and physical ailments and increase the quality of life among aging populations is timely and warranted. The purpose of this study in aging adult women was to explore if prayer is associated with electrical brain activity patterns consistent with meditation and therefore a likely pro-health behavior.

MATERIALS AND METHODS

A sample of 33 healthy women (M_age = 80.1, SD = 8.3) were recruited from a Midwestern Catholic Sisters community. Participants completed 6 consecutive, counterbalanced electroencephalogram (EEG) sessions: three resting sessions and three praying sessions equating to 18 min of recorded EEG data for each participant. Differences in alpha power and frontal alpha asymmetry (FAA) between praying and resting conditions and the influence of age on the association between inter-individual differences in alpha power were explored.

RESULTS

Results indicated significant higher alpha power detected in electrodes positioned in the occipital area for praying sessions compared to resting sessions. Additionally, we found significant positive correlations between FAA values and age of the participants for both conditions (rest: r = 0.436, p = 0.016; pray: r = 0.434, p = 0.017), indicating more approach-related brain activity in older participants.

CONCLUSIONS

Taken collectively, our results suggest that prayerful meditation increased alpha power and that positive and approach-related (left frontal-central) brain activity increased as Sisters aged. Future studies should explore the mediating role of age as it relates to meditation and cognitive outcomes.

Brain Functional Specialization Is Enhanced Among Tai Chi Chuan Practitioners

OBJECTIVE

To investigate the effect of long-term Tai Chi Chuan (TCC) practice on practitioners' brain functional specialization compare with the TCC novices.

DESIGN

A cross-sectional study.

SETTING

A psychology Institute.

PARTICIPANTS

TCC practitioners (N=22) (52.4±6.8y; 7 men; educated years: 12.18±3.03y) and 18 healthy adults (54.8±6.8y; 8 men; education years: 11.78±2.90y) matched by age, sex, and education were enrolled.

MAIN OUTCOME MEASURES

Participants underwent functional magnetic resonance imaging scanning and cognitive test to measure the differences in functional specialization and cognitive function. Functional specialization was evaluated by voxel-mirrored homotopic connectivity (VMHC) method.

RESULTS

Lower middle frontal gyrus VMHC in TCC practitioners compared to controls. For TCC practitioners, the longer they practice, the lower their VMHC in precentral and precuneus. TCC practitioners showed better cognition performance.

CONCLUSIONS

Changed VMHC indicated that TCC practice could enhance functional specialization in the middle frontal cortex of practitioners, which may be associated with higher-order cognitive ability.

The sampling precision of research in five major areas of psychology

After obtaining a sample of published, peer-reviewed articles from journals with high and low impact factors in social, cognitive, neuro-, developmental, and clinical psychology, we used a priori equations recently derived by Trafimow (Educational and Psychological Measurement, 77, 831-854, 2017; Trafimow & MacDonald in Educational and Psychological Measurement, 77, 204-219, 2017) to compute the articles' median levels of precision. Our findings indicate that developmental research performs best with respect to precision, whereas cognitive research performs the worst; however, none of the psychology subfields excelled. In addition, we found important differences in precision between journals in the upper versus lower echelons with respect to impact factors in cognitive, neuro-, and clinical psychology, whereas the difference was dramatically attenuated for social and developmental psychology. Implications are discussed.

Abnormal gray matter asymmetry in alcohol dependence

Previous voxel-based morphometry studies have provided evidence that patients with alcohol dependence (AD) have widespread gray matter morphological abnormalities. However, brain structural asymmetry in AD has not been assessed to date. Here, we aimed to use a recently developed voxel-based morphometry-based approach to investigate global and regional gray matter asymmetry alterations in AD. A total of 39 male individuals, including 19 AD patients and 20 age-matched healthy controls, underwent high-resolution structural MRI. Global and voxel-wise gray matter asymmetries were measured separately by the Dice coefficient and the asymmetry index, which were compared between the two groups. We found no difference in the global gray matter asymmetry between AD patients and healthy controls. However, voxel-wise gray matter asymmetry analysis showed that AD patients and healthy controls had different distribution patterns of brain regions with a rightward asymmetry and a leftward asymmetry Furthermore, we observed an increased rightward asymmetry of gray matter in the hemispheric I-IV and V of the cerebellum and lingual gyrus in AD patients. These findings suggest that abnormal structural asymmetry in the cerebellum and the primary visual cortex may be the neural mechanisms contributing toward motor and visual impairments in AD.

Evolution from four mental states to the highest state of consciousness: A neurophysiological basis of meditation as defined in yoga texts

This chapter provides a theoretical introduction to states of consciousness and reviews neuroscientific investigations of meditation. The different states of consciousness consist of four mental states, i.e., cancalata (random thinking), ekagrata (non-meditative focusing), dharna (focused meditation), and dhyana (meditation) as defined in yoga texts. Meditation is a self-regulated mental process associated with deep relaxation and increased internalized attention. Scientific investigations on meditation reported changes in electrophysiological signals and neuroimaging measures. But most outcomes of meditation studies showed inconsistent results, this may be due to heterogeneity in meditation methods and techniques evolved in the last 200 years. Traditionally, the features of meditation include the capacity to sustain a heightened awareness of thoughts, behaviors, emotions, and perceptions. Generally, meditation involves non-reactive effortless monitoring of the content of experience from moment to moment. Focused meditation practice involves awareness on a single object and open monitoring meditation is a non-directive meditation involved attention in breathing, mantra, or sound. Therefore, results of few empirical studies of advanced meditators or beginners remain tentative. This is an attempt to compile the meditation-related changes in electrophysiological and neuroimaging processes among experienced and novice practitioners.

Toward a brain theory of meditation

The rapidly progressing science of meditation has led to insights about the neural correlates of focused attention meditation (FAM), open monitoring meditation (OMM), compassion meditation (CM) and loving kindness meditation (LKM), in terms of states and traits. However, a unified theoretical understanding of the brain mechanisms involved in meditation-related functions, including mindfulness, is lacking. After reviewing the main forms of meditation and their relationships, the major brain networks and brain states, as well as influential theoretical views of consciousness, we outline a Brain Theory of Meditation (BTM). BTM takes the lead from considerations about the roles of the major brain networks, i.e., the central executive, salience and default mode networks, and their interplay, in meditation, and from an essential energetic limitation of the human brain, such that only up to 1% of the neurons in the cortex can be concurrently activated. The development of the theory is also guided by our neuroscientific studies with the outstanding participation of Theravada Buddhist monks, with other relevant findings in literature. BTM suggests mechanisms for the different forms of meditation, with the down-regulation of brain network activities in FAM, the gating and tuning of network coupling in OMM, and state-related up-regulation effects in CM and LKM. The theory also advances a leftward asymmetry in top-down regulation, and an enhanced inter-hemispheric integration, in meditation states and traits, also with implications for a theoretical understanding of conscious access. Meditation thus provides a meta-function for an efficient brain/mind regulation, and a flexible allocation of highly limited and often constrained (e.g., by negative emotion and mind wandering) brain activity resources, which can be related to mindfulness. Finally, a series of experimental predictions is derived from the theory.

In vivo magnetic resonance images reveal neuroanatomical sex differences through the application of voxel-based morphometry in C57BL/6 mice

Behaviorally relevant sex differences are often associated with structural differences in the brain and many diseases are sexually dimorphic in prevalence and progression. Characterizing sex differences is imperative to gaining a complete understanding of behavior and disease which will, in turn, allow for a balanced approach to scientific research and the development of therapies. In this study, we generated novel tissue probability maps (TPMs) based on 30 male and 30 female in vivo C57BL/6 mouse brain magnetic resonance images and used voxel-based morphometry (VBM) to analyze sex differences. Females displayed larger anterior hippocampus, basolateral amygdala, and lateral cerebellar cortex volumes, while males exhibited larger cerebral cortex, medial amygdala, and medial cerebellar cortex volumes. Atlas-based morphometry (ABM) revealed a statistically significant sex difference in cortical volume and no difference in whole cerebellar volume. This validated our VBM findings that showed a larger cerebral cortex in male mice and a pattern of dimorphism in the cerebellum where the lateral portion was larger in females and the medial portion was larger in males. These results are consonant with previous ex vivo studies examining sex differences, but also suggest further regions of interest.

Sexual dimorphism of Broca's region: More gray matter in female brains in Brodmann areas 44 and 45

Although a sexual dimorphism in brain structure is generally well established, evidence for sex differences in Brodmann areas (BA) 44 and 45 is inconclusive. This may be due to the difficulty of accurately defining BA 44 and BA 45 in magnetic resonance images, given that these regions are variable in their location and extent and that they do not match well with macroanatomic landmarks. Here we set out to test for possible sex differences in the local gray matter of BA 44/45 by integrating imaging-based signal intensities with cytoarchitectonically defined tissue probabilities in a sample of 50 male and 50 female subjects. In addition to testing for sex differences with respect to left- and right-hemispheric measures of BA 44/45, we also assessed possible sex differences in BA 44/45 asymmetry. Our analyses revealed significantly larger gray matter volumes in females compared with males for BA 44 and BA 45 bilaterally. However, there was a lack of significant sex differences in BA 44/45 asymmetry. These results corroborate reports of a language-related female superiority, particularly with respect to verbal fluency and verbal memory tasks. © 2016 Wiley Periodicals, Inc.

Ability to Gain Control Over One's Own Brain Activity and its Relation to Spiritual Practice: A Multimodal Imaging Study

Spiritual practice, such as prayer or meditation, is associated with focusing attention on internal states and self-awareness processes. As these cognitive control mechanisms presumably are also important for neurofeedback (NF), we investigated whether people who pray frequently (N = 20) show a higher ability of self-control over their own brain activity compared to a control group of individuals who rarely pray (N = 20). All participants underwent structural magnetic resonance imaging (MRI) and one session of sensorimotor rhythm (SMR, 12–15 Hz) based NF training. Individuals who reported a high frequency of prayer showed improved NF performance compared to individuals who reported a low frequency of prayer. The individual ability to control one’s own brain activity was related to volumetric aspects of the brain. In the low frequency of prayer group, gray matter volumes in the right insula and inferior frontal gyrus were positively associated with NF performance, supporting prior findings that more general self-control networks are involved in successful NF learning. In contrast, participants who prayed regularly showed a negative association between gray matter volume in the left medial orbitofrontal cortex (Brodmann’s area (BA) 10) and NF performance. Due to their regular spiritual practice, they might have been more skillful in gating incoming information provided by the NF system and avoiding task-irrelevant thoughts.

The structural neural substrate of subjective happiness

Happiness is a subjective experience that is an ultimate goal for humans. Psychological studies have shown that subjective happiness can be measured reliably and consists of emotional and cognitive components. However, the neural substrates of subjective happiness remain unclear. To investigate this issue, we used structural magnetic resonance imaging and questionnaires that assessed subjective happiness, the intensity of positive and negative emotional experiences, and purpose in life. We found a positive relationship between the subjective happiness score and gray matter volume in the right precuneus. Moreover, the same region showed an association with the combined positive and negative emotional intensity and purpose in life scores. Our findings suggest that the precuneus mediates subjective happiness by integrating the emotional and cognitive components of happiness.

Atypically rightward cerebral asymmetry in male adults with autism stratifies individuals with and without language delay

In humans, both language and fine motor skills are associated with left‐hemisphere specialization, whereas visuospatial skills are associated with right‐hemisphere specialization. Individuals with autism spectrum conditions (ASC) show a profile of deficits and strengths that involves these lateralized cognitive functions. Here we test the hypothesis that regions implicated in these functions are atypically rightward lateralized in individuals with ASC and, that such atypicality is associated with functional performance. Participants included 67 male, right‐handed adults with ASC and 69 age‐ and IQ‐matched neurotypical males. We assessed group differences in structural asymmetries in cortical regions of interest with voxel‐based analysis of grey matter volumes, followed by correlational analyses with measures of language, motor and visuospatial skills. We found stronger rightward lateralization within the inferior parietal lobule and reduced leftward lateralization extending along the auditory cortex comprising the planum temporale, Heschl's gyrus, posterior supramarginal gyrus, and parietal operculum, which was more pronounced in ASC individuals with delayed language onset compared to those without. Planned correlational analyses showed that for individuals with ASC, reduced leftward asymmetry in the auditory region was associated with more childhood social reciprocity difficulties. We conclude that atypical cerebral structural asymmetry is a potential candidate neurophenotype of ASC. Hum Brain Mapp 37:230–253, 2016. © 2015 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.

Reduced age-related degeneration of the hippocampal subiculum in long-term meditators

Normal aging is known to result in a reduction of gray matter within the hippocampal complex, particularly in the subiculum. The present study was designed to address the question whether the practice of meditation can amend this age-related subicular atrophy. For this purpose, we established the correlations between subicular volume and chronological age within 50 long-term meditators and 50 control subjects. High-resolution magnetic resonance imaging (MRI) scans were automatically processed combining cytoarchitectonically defined probabilistic maps with advanced tissue segmentation and registration methods. Overall, we observed steeper negative regression slopes in controls. The analysis further revealed a significant group-by-age interaction for the left subiculum with a significant negative correlation between age and subicular volume in controls, but no significant correlation in meditators. Altogether, these findings seem to suggest a reduced age-related atrophy of the left subiculum in meditators compared to healthy controls. Possible explanations might be a relative increase of subicular tissue over time through long-term training as meditation is a process that incorporates regular and ongoing mental efforts. Alternatively, because meditation is an established form of reducing stress, our observation might reflect an overall preservation of subicular tissue through a reduced neuronal vulnerability to negative effects of stress.

The Meditative Mind: A Comprehensive Meta-Analysis of MRI Studies

Over the past decade mind and body practices, such as yoga and meditation, have raised interest in different scientific fields; in particular, the physiological mechanisms underlying the beneficial effects observed in meditators have been investigated. Neuroimaging studies have studied the effects of meditation on brain structure and function and findings have helped clarify the biological underpinnings of the positive effects of meditation practice and the possible integration of this technique in standard therapy. The large amount of data collected thus far allows drawing some conclusions about the neural effects of meditation practice. In the present study we used activation likelihood estimation (ALE) analysis to make a coordinate-based meta-analysis of neuroimaging data on the effects of meditation on brain structure and function. Results indicate that meditation leads to activation in brain areas involved in processing self-relevant information, self-regulation, focused problem-solving, adaptive behavior, and interoception. Results also show that meditation practice induces functional and structural brain modifications in expert meditators, especially in areas involved in self-referential processes such as self-awareness and self-regulation. These results demonstrate that a biological substrate underlies the positive pervasive effect of meditation practice and suggest that meditation techniques could be adopted in clinical populations and to prevent disease.

Meditation reduces pain-related neural activity in the anterior cingulate cortex, insula, secondary somatosensory cortex, and thalamus

Recent studies have shown that meditation inhibits or relieves pain perception. To clarify the underlying mechanisms for this phenomenon, neuroimaging methods, such as functional magnetic resonance imaging, and neurophysiological methods, such as magnetoencephalography and electroencephalography, have been used. However, it has been difficult to interpret the results, because there is some paradoxical evidence. For example, some studies reported increased neural responses to pain stimulation during meditation in the anterior cingulate cortex (ACC) and insula, whereas others showed a decrease in these regions. There have been inconsistent findings to date. Moreover, in general, since the activities of the ACC and insula are correlated with pain perception, the increase in neural activities during meditation would be related to the enhancement of pain perception rather than its reduction. These contradictions might directly contribute to the ‘mystery of meditation.’ In this review, we presented previous findings for brain regions during meditation and the anatomical changes that occurred in the brain with long-term meditation training. We then discussed the findings of previous studies that examined pain-related neural activity during meditation. We also described the brain mechanisms responsible for pain relief during meditation, and possible reasons for paradoxical evidence among previous studies. By thoroughly overviewing previous findings, we hypothesized that meditation reduces pain-related neural activity in the ACC, insula, secondary somatosensory cortex, and thalamus. We suggest that the characteristics of the modulation of this activity may depend on the kind of meditation and/or number of years of experience of meditation, which were associated with paradoxical findings among previous studies that investigated pain-related neural activities during meditation.

Brain Gray Matter Changes Associated with Mindfulness Meditation in Older Adults: An Exploratory Pilot Study using Voxel-based Morphometry

Background

Mindfulness-based interventions (MBIs) have previously been associated with structural gray matter changes in normal healthy adults. However, it remains unknown if standardized MBIs can induce similar changes in older adults and those with health complaints as well. The objective of this investigation was to examine the effect of a standardized MBI on the gray matter tissue of older adults with sleep disturbances.

Methods

This exploratory single-group pilot longitudinal study examined local gray matter changes over a six-week MBI period. Participants included six older adult community volunteers (M=66.5 years of age, SD=5.5, range=58–75; 66% female) with sleep disturbances recruited through advertisement in local newspapers/flyers posted at a university medical center and affiliated clinics in Los Angeles, CA. The MBI was delivered as a weekly, two-hour, six-session, group-based course in mindfulness meditation. Gray matter was measured voxel-wise pre- and post-intervention.

Results

A significant gray matter increase was identified within the precuneus, possibly implicating meditation-induced changes of the default mode network. In contrast, observed significant gray matter decreases may have been driven by MBI-related remediation of brain architecture subserving sleep complaints.

Conclusions

Exploratory findings suggest that mindfulness meditation practice is associated with a detectable alteration of cerebral gray matter in older adults.