Processing of proprioceptive and vestibular body signals and self-transcendence in Ashtanga yoga practitioners

The role of non-ordinary states of consciousness occasioned by mind-body practices in mental health illness

BACKGROUND

Research with hallucinogens suggests that non-ordinary states of consciousness (NOSCs), particularly mystical-type experiences, predict improvements in various affective disorders and substance use disorders (SUDs). Little is known, however, about the therapeutic potential of NOSCs induced by mind-body practices such as meditation, yoga and breathwork.

METHODS

We conducted a literature review in online databases (PubMed, Scopus, Google Scholar) and preprint databases (SSRN, bioRxiv) to identify studies of NOSCs induced by mind-body practices and their effects in affective disorders and SUDs.

RESULTS

A wide variety of mind-body practices involving physical movement (i.e., shamanic drumming, yoga) and hyper-focused immersive mental experiences (i.e., meditation, breathwork) have been reported in the literature. Preliminary evidence, mostly from qualitative studies and open label studies, suggest that mind-body practices produce NOSCs. Such experiences have been associated with short-term reduced levels of anxiety and depression, increased motivation to quit addictive behaviors, and enhanced self-awareness and spiritual well-being.

LIMITATIONS

Findings are limited by the scarcity of literature in this field. Further rigorous and methodologically sound empirical research is needed, including comparative studies of NOSCs occasioned by different methods.

CONCLUSIONS

Mind-body practices may represent a promising approach for treating mental health disorders. The NOSCs induced by such practices may lead to beneficial shifts in perceptions, values, beliefs, and behaviors. Given the challenges with hallucinogen-based therapies, mind-body practices may represent a more accessible and acceptable way of eliciting potentially helpful NOSCs in clinical practice.

Superior Gait Symmetry and Postural Stability among Yoga Instructors-Inertial Measurement Unit-Based Evaluation

This study investigates gait symmetry and single-leg stance balance of professional yoga instructors versus age-matched typically developed controls using inertial measurement unit (IMU)-based evaluation. We recruited twenty-five yoga instructors and twenty-five healthy control subjects to conduct the walking experiments and single-leg stance tests. Kinematic data were measured by attaching IMUs to the lower limbs and trunk. We assessed the asymmetry of swing phases during the normal-walk and tandem-walk tests with eyes open and closed, respectively. The subjects subsequently conducted four single-leg stance tests, including a single-leg stance on both legs with eyes open and closed. Two balance indexes regarding the angular velocities of the waist and chest were defined to assess postural stability. The gait asymmetry indexes of yoga instructors were significantly lower than those of the typically developed controls. Similarly, the yoga instructors had better body balance in all four single-leg stance tests. This study's findings suggest that yoga improves gait asymmetry and balance ability in healthy adults. In the future, further intervention studies could be conducted to confirm the effect of yoga training.

Applying the S-ART Framework to Yoga: Exploring the Self-Regulatory Action of Yoga Practice in Two Culturally Diverse Samples

Mindfulness practices form the core of numerous therapeutic programs and interventions for stress reduction and the treatment of different health conditions related to stress and life habits. Ways and means to regulate oneself effectively also form the foundation of the path of yoga in the accomplishment of holistic health and well-being. The self-awareness, self-regulation, and self-transcendence (S-ART) model can be considered as an overarching neurobiological framework to explain the self-regulatory mechanisms of well-being present in mindfulness-based practices. The current study, by connecting and applying the S-ART framework to the self-regulatory mechanisms in yoga and generating related hypotheses, provides a theory-led explanation of the action of yoga practices, which is sparse in the literature. Testing the S-ART model in yoga in two culturally diverse samples, assessing the model-mapped psychological mechanisms of action, and exploring the influence of perseverance in yoga practice are the original contributions of this study. The study sample comprised 362 yoga practitioners and non-practitioners (197 Indian and 165 Spanish), who completed four tests of psychological variables indicative of the aforementioned three S-ART abilities. These tests were Multidimensional Assessment of Interoceptive Awareness (MAIA), Experiences Questionnaire-Decentering (EQ-D) subscale, Difficulties in Emotion Regulation Scale (DERS), and Relational Compassion Scale (RCS). The results indicated significantly better self-awareness and self-regulatory abilities in yoga practitioners (Indian and Spanish in a combination) than non-practitioners, reflected in higher levels of interoceptive awareness and decentering abilities. Moreover, perseverance in yoga practice acted as a significant predictor of self-awareness and self-regulation in practitioners. An analysis of each cultural sample revealed some differences. Yoga practice and perseverance in it acted as a significant predictor of interoceptive awareness and decentering in Indian practitioners having more than 1 year of sustained yoga practice, but for the Spanish participants, physical exercise and frequency of yoga practice acted as better predictors of interoceptive awareness and decentering in comparison to yoga practice and perseverance in it. The obtained results suggested that the S-ART model provided preliminary but promising evidence for the self-regulatory mechanisms of action in yoga practice within a culturally diverse sample of yoga practitioners. This study also widens the scope of generating further hypotheses using the S-ART theoretical framework for testing the self-regulatory mechanisms of action in yoga practice.

Real-World fNIRS Brain Activity Measurements during Ashtanga Vinyasa Yoga

Functional near-infrared spectroscopy (fNIRS) is often praised for its portability and robustness towards motion artifacts. While an increasing body of fNIRS research in real-world environments is emerging, most fNIRS studies are still conducted in laboratories, and do not incorporate larger movements performed by participants. This study extends fNIRS applications in real-world environments by conducting a single-subject observational study of a yoga practice with considerable movement (Ashtanga Vinyasa Yoga) in a participant's natural environment (their apartment). The results show differences in cognitive load (prefrontal cortex activation) when comparing technically complex postures to relatively simple ones, but also some contrasts with surprisingly little difference. This study explores the boundaries of real-world cognitive load measurements, and contributes to the empirical knowledge base of using fNIRS in realistic settings. To the best of our knowledge, this is the first demonstration of fNIRS brain imaging recorded during any moving yoga practice. Future work with fNIRS should take advantage of this by accomplishing studies with considerable real-world movement.

Exploring how different types of yoga change psychological resources and emotional well-being across a single session

OBJECTIVES

Yoga demonstrates beneficial effects in many populations, yet our understanding of how yoga brings about these effects is quite limited. Among the proposed mechanisms of yoga are increasing psychological resources (mindfulness, body consciousness, self-transcendence, spiritual peace, and social connectedness) that may bring about salutary effects on emotional wellbeing. Further, yoga is a complex practice comprising meditation, active and restorative postures, and breathwork; however little is known about how different components may affect mechanisms. We aimed to determine how an acute session of yoga (and its specific components) related to pre- to post- session changes in proposed mechanisms (psychological resources) and whether those changes were associated with positive changes in emotions.

DESIGN

144 regular yoga practitioners completed measures of mindfulness, body consciousness, self-transcendence, social connectedness, spiritual peace, and exercise-induced emotions (positive engagement, revitalization, tranquility, exhaustion) immediately before and after a yoga session (N = 11 sessions, each a different type of yoga). Perceived properties of each yoga session, exercise exertion and engagement with the yoga teacher were assessed immediately following the session.

RESULTS

Pre-to post- yoga, levels of positive emotions (engagement, tranquility and revitalization) increased while exhaustion decreased. Further, all psychological resources increased and closely tracked improved emotions. Additionally, aspects of the yoga session correlated with changes in psychological resources (mechanisms) and emotions.

CONCLUSIONS

Yoga may influence multiple psychological mechanisms that influence emotional well-being. Further, different types of yoga may affect different mechanisms. Results can inform yoga interventions aiming to optimize effects through specific mechanisms such as mindfulness or spirituality.

Visual dependency and postural control on swing performance in golf players

Individuals have to reweight the respective contribution of the different sources of sensorial information for regulating posture and balance, especially during fine task execution. Given the evidences indicating strategy during swing performance as associated with prioritization of task-relevant visuospatial information for skill execution, the aim of the present work is to assess differences in visual dependency (VD) and postural control in a population of expert (EXP) and non-expert (NEXP) golfers when compared with healthy subjects (HC) and to discover possible relationships between these outcomes and swing performance. Thus, 15 golfers (EXP = 7; NEXP = 8) and 32 matched HC underwent otoneurological testing including video Head Impulse Test, posturography and Rod and Disk Test (RDT). Golf players also underwent a swing session procedure, which performance was measured by means of the Flightscope X2 Doppler-radar launch monitor system. EXP subjects demonstrated significant (p < 0.05) lower values in i) counter-clockwise (CCW) and clockwise (CW) dynamic conditions when compared with both NEXP and HC subjects RDT outcome measures and ii) surface and length posturography values as compared with HC subjects. When treating golf players outcomes as 'a continuum', CCW and CW scores were found to positively correlate with both lateral distance and horizontal launch angle and to negatively correlate with spin rpm. In conclusion, the present study suggests that the high-level of visual-independency demonstrated by EXP subjects may be functionally related in expert golfers to an effective motor strategy preferentially not referring to an inappropriate reliance on visual input.

Perception of Upright: Multisensory Convergence and the Role of Temporo-Parietal Cortex

We inherently maintain a stable perception of the world despite frequent changes in the head, eye, and body positions. Such "orientation constancy" is a prerequisite for coherent spatial perception and sensorimotor planning. As a multimodal sensory reference, perception of upright represents neural processes that subserve orientation constancy through integration of sensory information encoding the eye, head, and body positions. Although perception of upright is distinct from perception of body orientation, they share similar neural substrates within the cerebral cortical networks involved in perception of spatial orientation. These cortical networks, mainly within the temporo-parietal junction, are crucial for multisensory processing and integration that generate sensory reference frames for coherent perception of self-position and extrapersonal space transformations. In this review, we focus on these neural mechanisms and discuss (i) neurobehavioral aspects of orientation constancy, (ii) sensory models that address the neurophysiology underlying perception of upright, and (iii) the current evidence for the role of cerebral cortex in perception of upright and orientation constancy, including findings from the neurological disorders that affect cortical function.

Interactions Between Body and Social Awareness in Yoga

BACKGROUND/OBJECTIVE

Bodily processes have been intimately linked to social-cognitive and affective functions, such as compassion and empathy. Yet, little is known about how awareness of bodily processes influences social awareness and vice versa, especially in nonobservational but experiential investigations. This study investigated the relationship between psychometrically reported body and social awareness (including altruism, empathy, perspective-taking, and compassion) in 90 yoga and yoga-/mediation-naive control participants. In modern postural yoga, advanced practitioners claim both increased compassion and inner focus.

METHODS

Multiple regression analyses were conducted to predict (1) the level of yoga practice from body awareness and social awareness skills in the yoga group and (2) body awareness from social skills in both groups.

RESULTS

Body awareness and compassion were significant positive and independent predictors of yoga expertise. This finding supports practitioners' anecdotal claims but also implies that both functions tap into different aspects of yoga expertise. When body awareness was predicted, altruism emerged as a significant negative predictor in the yoga group (but not control group) as a function of yoga practice.

CONCLUSION

These results might compellingly suggest that, despite high compassion, heightened bodily self-awareness might increase a self-centred perspective and limit altruistic acts in advanced yoga practitioners.

The Sense of Agency Is More Sensitive to Manipulations of Outcome than Movement-Related Feedback Irrespective of Sensory Modality

The sense of agency describes the ability to experience oneself as the agent of one's own actions. Previous studies of the sense of agency manipulated the predicted sensory feedback related either to movement execution or to the movement's outcome, for example by delaying the movement of a virtual hand or the onset of a tone that resulted from a button press. Such temporal sensorimotor discrepancies reduce the sense of agency. It remains unclear whether movement-related feedback is processed differently than outcome-related feedback in terms of agency experience, especially if these types of feedback differ with respect to sensory modality. We employed a mixed-reality setup, in which participants tracked their finger movements by means of a virtual hand. They performed a single tap, which elicited a sound. The temporal contingency between the participants' finger movements and (i) the movement of the virtual hand or (ii) the expected auditory outcome was systematically varied. In a visual control experiment, the tap elicited a visual outcome. For each feedback type and participant, changes in the sense of agency were quantified using a forced-choice paradigm and the Method of Constant Stimuli. Participants were more sensitive to delays of outcome than to delays of movement execution. This effect was very similar for visual or auditory outcome delays. Our results indicate different contributions of movement- versus outcome-related sensory feedback to the sense of agency, irrespective of the modality of the outcome. We propose that this differential sensitivity reflects the behavioral importance of assessing authorship of the outcome of an action.

Minding the Mechanisms: A Discussion of How Mindfulness Leads to Positive Outcomes at Work

Hyland, Lee, and Mills (2015) asserted that the many benefits of mindfulness practices have been underutilized and understudied at work. We agree with the focal article's stance that more research is needed on mindfulness at work. We extend this argument to include a request that future research pays attention to the mechanisms responsible for the effects of mindfulness at work. In this commentary, we (a) briefly discuss the practical importance of understanding the mechanisms by which mindfulness practices lead to positive outcomes, (b) outline the mediating mechanisms proposed by the leading theoretical model of mindfulness effects and how those mediators apply to work, and (c) argue that more rigorous, empirical research is needed to understand the mechanisms through which mindfulness practices lead to positive work outcomes.

The right temporoparietal junction plays a causal role in maintaining the internal representation of verticality

Perception of the visual vertical is strongly based on our ability to match visual inflow with vestibular, proprioceptive, tactile, and even visceral information that contributes to maintaining an internal representation of the vertical. An important cortical region implicated in multisensory integration is the right temporoparietal junction (rTPJ), which also is involved in higher order forms of body- and space-related cognition. To test whether this region integrates body-related multisensory information necessary for establishing the subjective visual vertical, we combined a psychophysical task (the rod-and-frame test) with transient inhibition of the rTPJ via continuous theta burst stimulation (cTBS). A Gabor patch visual detection task was used as a control visual task. cTBS of early visual cortex (V1-V3) was used to test whether early visual cortices played any role in verticality estimation. We show that inhibition of rTPJ activity selectively impairs the ability to evaluate the rod's verticality when no contextual visual information, such as a frame surrounding the rod, is provided. Conversely, transient inhibition of V1-V3 selectively disrupts the ability to visually detect Gabor patch orientation. This anatomofunctional dissociation supports the idea that the rTPJ plays a causal role in integrating egocentric sensory information encoded in different reference systems (i.e., vestibular and somatic) to maintain an internal representation of verticality.

Ashtanga-Based Yoga Therapy Increases the Sensory Contribution to Postural Stability in Visually-Impaired Persons at Risk for Falls as Measured by the Wii Balance Board: A Pilot Randomized Controlled Trial

Objective

Persons with visual impairment (VI) are at greater risk for falls due to irreparable damage to visual sensory input contributing to balance. Targeted training may significantly improve postural stability by strengthening the remaining sensory systems. Here, we evaluate the Ashtanga-based Yoga Therapy (AYT) program as a multi-sensory behavioral intervention to develop postural stability in VI.

Design

A randomized, waitlist-controlled, single-blind clinical trial

Methods

The trial was conducted between October 2012 and December 2013. Twenty-one legally blind participants were randomized to an 8-week AYT program (n = 11, mean (SD) age = 55(17)) or waitlist control (n=10, mean (SD) age = 55(10)). AYT subjects convened for one group session at a local yoga studio with an instructor and two individual home-based practice sessions per week for a total of 8 weeks. Subjects completed outcome measures at baseline and post-8 weeks of AYT. The primary outcome, absolute Center of Pressure (COP), was derived from the Wii Balance Board (WBB), a standalone posturography device, in 4 sensory conditions: firm surface, eyes open (EO); firm surface, eyes closed (EC); foam surface, EO; and foam surface, EC. Stabilization Indices (SI) were computed from COP measures to determine the relative visual (SI_firm, SI_foam), somatosensory (SI_EO, SI_EC) and vestibular (SI_V, i.e., Foam_EC vs. Firm_EO) contributions to balance. This study was not powered to detect between group differences, so significance of pre-post changes was assessed by paired samples t-tests within each group.

Results

Groups were equivalent at baseline (all p > 0.05). In the AYT group, absolute COP significantly increased in the Foam_EO (t(8) = -3.66, p = 0.01) and Foam_EC (t(8) = -3.90, p = 0.01) conditions. Relative somatosensory SI_EO (t(8) = -2.42, p = 0.04) and SI_EC (t(8) = -3.96, p = 0.01), and vestibular SI_V (t(8) = -2.47, p = 0.04) contributions to balance increased significantly. As expected, no significant changes from EO to EC conditions were found indicating an absence of visual dependency in VI. No significant pre-post changes were observed in the control group (all p > 0.05).

Conclusions

These preliminary results establish the potential for AYT training to develop the remaining somatosensory and vestibular responses used to optimize postural stability in a VI population.

Trial Registration

www.ClinicalTrials.govNCT01366677

Meditation has stronger relationships with mindfulness, kundalini, and mystical experiences than yoga or prayer

Contemplative practices can have profound effects on mindfulness and on physical and sensory and mystical experiences. Individuals who self-reported meditation, yoga, contemplative prayer, or a combination of practices and their patterns of practice were compared for mindfulness, kundalini effects, and mystical experiences. The results suggest that the amount of practice but not the pattern and social conditions of practice influences mindfulness and possibly mystical experiences. Meditation, yoga, contemplative prayer, or a combination of practices all were found to be associated with enhancements of mindfulness, kundalini effects, and mystical experiences, but meditation had particularly strong associations and may be the basis of the associations of yoga and prayer with these outcomes. The results further suggest that the primary association of contemplative practices is with the real time awareness and appreciation of sensory and perceptual experiences which may be the intermediary between disparate practices and mindfulness, kundalini effects, and mystical experiences.

Neurophysiological and neurocognitive mechanisms underlying the effects of yoga-based practices: towards a comprehensive theoretical framework

During recent decades numerous yoga-based practices (YBP) have emerged in the West, with their aims ranging from fitness gains to therapeutic benefits and spiritual development. Yoga is also beginning to spark growing interest within the scientific community, and yoga-based interventions have been associated with measureable changes in physiological parameters, perceived emotional states, and cognitive functioning. YBP typically involve a combination of postures or movement sequences, conscious regulation of the breath, and various techniques to improve attentional focus. However, so far little if any research has attempted to deconstruct the role of these different component parts in order to better understand their respective contribution to the effects of YBP. A clear operational definition of yoga-based therapeutic interventions for scientific purposes, as well as a comprehensive theoretical framework from which testable hypotheses can be formulated, is therefore needed. Here we propose such a framework, and outline the bottom-up neurophysiological and top-down neurocognitive mechanisms hypothesized to be at play in YBP.