Coupling of respiration and attention via the locus coeruleus: Effects of meditation and pranayama

Greater physical fitness ( VO 2 max $$ {\mathrm{VO}}_{2_{\mathrm{max}}} $$ ) in healthy older adults associated with increased integrity of the locus coeruleus-noradrenergic system

AIM

Physical activity (PA) is a key component for brain health and Reserve, and it is among the main dementia protective factors. However, the neurobiological mechanisms underpinning Reserve are not fully understood. In this regard, a noradrenergic (NA) theory of cognitive reserve (Robertson, 2013) has proposed that the upregulation of NA system might be a key factor for building reserve and resilience to neurodegeneration because of the neuroprotective role of NA across the brain. PA elicits an enhanced catecholamine response, in particular for NA. By increasing physical commitment, a greater amount of NA is synthetised in response to higher oxygen demand. More physically trained individuals show greater capabilities to carry oxygen resulting in greaterVo 2 max $$ {\mathrm{Vo}}_{2_{\mathrm{max}}} $$ - a measure of oxygen uptake and physical fitness (PF).

METHODS

We hypothesized that greaterVo 2 max $$ {\mathrm{Vo}}_{2_{\mathrm{max}}} $$ would be related to greater Locus Coeruleus (LC) MRI signal intensity. In a sample of 41 healthy subjects, we performed Voxel-Based Morphometry analyses, then repeated for the other neuromodulators as a control procedure (Serotonin, Dopamine and Acetylcholine).

RESULTS

As hypothesized, greaterVo 2 max $$ {\mathrm{Vo}}_{2_{\mathrm{max}}} $$ related to greater LC signal intensity, and weaker associations emerged for the other neuromodulators.

CONCLUSION

This newly established link betweenVo 2 max $$ {\mathrm{Vo}}_{2_{\mathrm{max}}} $$ and LC-NA system offers further understanding of the neurobiology underpinning Reserve in relationship to PA. While this study supports Robertson's theory proposing the upregulation of the NA system as a possible key factor building Reserve, it also provides ground for increasing LC-NA system resilience to neurodegeneration viaVo 2 max $$ {\mathrm{Vo}}_{2_{\mathrm{max}}} $$ enhancement.

Phase-locked breathing does not affect episodic visual recognition memory but does shape its corresponding ERPs

Recent studies have indicated that breathing shapes the underlying oscillatory brain activity critical for episodic memory, potentially impacting memory performance. However, the literature has presented conflicting results, with some studies suggesting that nasal inhalation enhances visual memory performance, while others have failed to observe any significant effects. Furthermore, the specific influence of breathing route (nasal vs. mouth) and the precise phase of the respiratory cycle during which stimuli are presented have remained elusive. To address this, we employed a visual recognition memory (VRM) and electroencephalography paradigm in which stimuli presentation was phase-locked to either inhalation or exhalation onset, using a within-subject design where participants performed the memory task while engaging in separate sessions of nose and mouth breathing. We show that neither breathing route nor breathing phase has a significant impact on VRM performance as measured by d-prime, with the data supporting the null hypothesis. However, we did find an effect of breathing phase on response bias, with participants adopting a more conservative decision criterion during exhalation. Moreover, we found that breathing phase during memory encoding shaped the late parietal effect (LPE) amplitude, while the Frontal Negative Component (FN400) and LPE during recognition were less impacted. While our study demonstrates that breathing does not shape VRM performance, it shows that it influences brain activity, reinforcing the importance of further research to elucidate the extent of respiratory influence on perception, cognition, and behavior.

Putting back respiration into respiratory sinus arrhythmia or high-frequency heart rate variability: Implications for interpretation, respiratory rhythmicity, and health

Research on respiratory sinus arrhythmia, or high-frequency heart rate variability (its frequency-domain equivalent), has been popular in psychology and the behavioral sciences for some time. It is typically interpreted as an indicator of cardiac vagal activity. However, as research has shown for decades, the respiratory pattern can influence the amplitude of these noninvasive measures substantially, without necessarily reflecting changes in tonic cardiac vagal activity. Although changes in respiration are systematically associated with experiential and behavioral states, this potential confound in the interpretation of RSA, or HF-HRV, is rarely considered. Interpretations of within-individual changes in these parameters are therefore only conclusive if undertaken relative to the breathing pattern. The interpretation of absolute levels of these parameters between individuals is additionally burdened with the problem of residual inspiratory cardiac vagal activity in humans. Furthermore, multiple demographic, anthropometric, life-style, health, and medication variables can act as relevant third variables that might explain associations of RSA or HF-HRV with experiential and behavioral variables. Because vagal activity measured by these parameters only represents the portion of cardiac vagal outflow that is modulated by the respiratory rhythm, alternative interpretations beyond cardiac vagal activity should be considered. Accumulating research shows that activity of multiple populations of neurons in the brain and the periphery, and with that organ activity and function, are modulated rhythmically by respiratory activity. Thus, observable health benefits ascribed to the cardiac vagal system through RSA or HF-HRV may actually reflect beneficial effects of respiratory modulation. Respiratory rhythmicity may ultimately provide the mechanism that integrates central, autonomic, and visceral activities.

Daily biofeedback to modulate heart rate oscillations affects structural volume in hippocampal subregions targeted by the locus coeruleus in older adults but not younger adults

Using data from a clinical trial, we tested the hypothesis that daily sessions modulating heart rate oscillations affect older adults' volume of a region-of-interest (ROI) comprised of adjacent hippocampal subregions with relatively strong locus coeruleus (LC) noradrenergic input. Younger and older adults were randomly assigned to one of two daily biofeedback practices for 5 weeks: (1) engage in slow-paced breathing to increase the amplitude of oscillations in heart rate at their breathing frequency (Osc+); (2) engage in self-selected strategies to decrease heart rate oscillations (Osc-). The interventions did not significantly affect younger adults' hippocampal volume. Among older adults, the two conditions affected volume in the LC-targeted hippocampal ROI differentially as reflected in a significant condition × time-point interaction on ROI volume. These condition differences were driven by opposing changes in the two conditions (increased volume in Osc+ and decreased volume in Osc-) and were mediated by the degree of heart rate oscillation during training sessions.

A systematic review and activation likelihood estimation meta-analysis of fMRI studies on arousing or wake-promoting effects in Buddhist meditation

Conventional Buddhist texts illustrate meditation as a condition of relaxed alertness that must fend against extreme hypoarousal (sleep, drowsiness) and extreme hyperarousal (restlessness). Theoretical, neurophysiological, and neuroimaging investigations of meditation have highlighted the relaxing effects and hypoarousing without emphasizing the alertness-promoting effects. Here we performed a systematic review supported by an activation-likelihood estimate (ALE) meta-analysis in an effort to counterbalance the surfeit of scholarship emphasizing the hypoarousing and relaxing effects of different forms of Buddhist meditation. Specifically, the current systematic review-cum-meta-analytical review seeks to highlight more support for meditation's wake-promoting effects by drawing from neuroimaging research during wakefulness and meditation. In this systematic review and meta-analysis of 22 fMRI studies, we aim to highlight support for Buddhist meditation's wake-promoting or arousing effects by identifying brain regions associated with alertness during meditation. The most significant peaks were localized medial frontal gyrus (MFG) and precuneus. We failed to determine areas ostensibly common to alertness-related meditation such as the medial prefrontal cortex (mPFC), superior parietal lobule, basal ganglia, thalamus, most likely due to the relatively fewer fMRI investigations that used wakefulness-promoting meditation techniques. Also, we argue that forthcoming research on meditation, related to alertness or wakefulness, continues to adopt a multi-modal method to investigate the correlation between actual behaviors and neural networks connected to Buddhist meditation. Moreover, we recommend the implementation of fMRI paradigms on Buddhist meditation with clinically diagnosed participants to complement recent trends in psychotherapy such as mindfulness-based cognitive therapy (MBCT).

From Lung to Brain: Respiration Modulates Neural and Mental Activity

Respiration protocols have been developed to manipulate mental states, including their use for therapeutic purposes. In this systematic review, we discuss evidence that respiration may play a fundamental role in coordinating neural activity, behavior, and emotion. The main findings are: (1) respiration affects the neural activity of a wide variety of regions in the brain; (2) respiration modulates different frequency ranges in the brain's dynamics; (3) different respiration protocols (spontaneous, hyperventilation, slow or resonance respiration) yield different neural and mental effects; and (4) the effects of respiration on the brain are related to concurrent modulation of biochemical (oxygen delivery, pH) and physiological (cerebral blood flow, heart rate variability) variables. We conclude that respiration may be an integral rhythm of the brain's neural activity. This provides an intimate connection of respiration with neuro-mental features like emotion. A respiratory-neuro-mental connection holds the promise for a brain-based therapeutic usage of respiration in mental disorders.

Greater physical fitness (Vo2Max) in healthy older adults associated with increased integrity of the Locus Coeruleus-Noradrenergic system

Physical activity (PA) is a key component for brain health and Reserve, and it is among the main dementia protective factors. However, the neurobiological mechanisms underpinning Reserve are not fully understood. In this regard, a noradrenergic (NA) theory of cognitive reserve (Robertson, 2013) has proposed that the upregulation of NA system might be a key factor for building reserve and resilience to neurodegeneration because of the neuroprotective role of NA across the brain. PA elicits an enhanced catecholamine response, in particular for NA. By increasing physical commitment, a greater amount of NA is synthetised in response to higher oxygen demand. More physically trained individuals show greater capabilities to carry oxygen resulting in greater Vo2max - a measure of oxygen uptake and physical fitness (PF). In the current study, we hypothesised that greater Vo2 max would be related to greater Locus Coeruleus (LC) MRI signal intensity. As hypothesised, greater Vo2max related to greater LC signal intensity across 41 healthy adults (age range 60-72). As a control procedure, in which these analyses were repeated for the other neuromodulators' seeds (for Serotonin, Dopamine and Acetylcholine), weaker associations emerged. This newly established link between Vo2max and LC-NA system offers further understanding of the neurobiology underpinning Reserve in relationship to PA. While this study supports Robertson's theory proposing the upregulation of the noradrenergic system as a possible key factor building Reserve, it also provide grounds for increasing LC-NA system resilience to neurodegeneration via Vo2max enhancement.

Daily biofeedback to modulate heart rate oscillations affects structural volume in hippocampal subregions targeted by the locus coeruleus in older adults but not younger adults

Using data from a clinical trial, we tested the hypothesis that daily sessions modulating heart rate oscillations affect older adults' volume of a region-of-interest (ROI) comprised of adjacent hippocampal subregions with relatively strong locus coeruleus (LC) noradrenergic input. Younger and older adults were randomly assigned to one of two daily biofeedback practices for 5 weeks: 1) engage in slow-paced breathing to increase the amplitude of oscillations in heart rate at their breathing frequency (Osc+); 2) engage in self-selected strategies to decrease heart rate oscillations (Osc-). The interventions did not significantly affect younger adults' hippocampal volume. Among older adults, the two conditions affected volume in the LC-targeted hippocampal ROI differentially as reflected in a significant condition x time-point interaction on ROI volume. These condition differences were driven by opposing changes in the two conditions (increased volume in Osc+ and decreased volume in Osc-) and were mediated by the degree of heart rate oscillation during training sessions.

Inhalation boosts perceptual awareness and decision speed

The emergence of consciousness is one of biology's biggest mysteries. During the past two decades, a major effort has been made to identify the neural correlates of consciousness, but in comparison, little is known about the physiological mechanisms underlying first-person subjective experience. Attention is considered the gateway of information to consciousness. Recent work suggests that the breathing phase (i.e., inhalation vs. exhalation) modulates attention, in such a way that attention directed toward exteroceptive information would increase during inhalation. One key hypothesis emerging from this work is that inhalation would improve perceptual awareness and near-threshold decision-making. The present study directly tested this hypothesis. We recorded the breathing rhythms of 30 humans performing a near-threshold decision-making task, in which they had to decide whether a liminal Gabor was tilted to the right or the left (objective decision task) and then to rate their perceptual awareness of the Gabor orientation (subjective decision task). In line with our hypothesis, the data revealed that, relative to exhalation, inhalation improves perceptual awareness and speeds up objective decision-making, without impairing accuracy. Overall, the present study builds on timely questions regarding the physiological mechanisms underlying consciousness and shows that breathing shapes the emergence of subjective experience and decision-making.NEW & NOTEWORTHY Breathing is a ubiquitous biological rhythm in animal life. However, little is known about its effect on consciousness and decision-making. Here, we measured the respiratory rhythm of humans performing a near-threshold discrimination experiment. We show that inhalation, compared with exhalation, improves perceptual awareness and accelerates decision-making while leaving accuracy unaffected.

Respiratory entrainment of the locus coeruleus modulates arousal level to avoid physical risks from external vibration

Slow rocking chairs can easily put people to sleep, while violent shaking, such as during earthquakes, may lead to rapid awakening. However, the influence of external body vibrations on arousal remains unclear. Herein, a computational model of a locus coeruleus (LC)-norepinephrine (NE) system and cardio-respiratory system were used to show that respiratory entrainment of the LC modulates arousal levels, which is an adaptation to avoid physical risks from external vibration. External vibrations of sinusoidal waves with different frequencies ranging from 0.1 to 20 [Hz] were applied to the LC based on the results of previous studies. We found that respiratory entrainment of the LC decreased the breathing rate (BR) and heart rate (HR) to maintain the HR within its normal range. Furthermore, 1:1 phase locking enhanced arousal level while phase-amplitude coupling decreased it for larger vibration stimuli. These findings suggest that respiratory entrainment of the LC might automatically modulate cardio-respiratory system homeostasis and arousal levels for performance readiness (fight/flight or freeze) to avoid physical risks from larger external vibrations.

Effects of respiratory phases on the processing of emotional and non-emotional visual stimuli

The number of studies investigating the relationship between respiratory phases and cognitive/neural processing of external events has been increasing, but the findings remain controversial. This registered report examined the effect of the respiratory phase on the discrimination accuracy of visual stimuli in the emotional and non-emotional domains. Forty-two healthy young participants were asked to choose fearful over neutral facial expressions and to choose high-contrast over low-contrast Gabor patches during spontaneous nasal respiration. Event-related potentials (ERPs) were also recorded for each type of stimulus presented during each respiratory phase. It was hypothesized that discrimination accuracy would be higher when the stimuli were presented during inhalation than during exhalation. It was also hypothesized that the amplitudes of ERPs elicited by the stimuli would be greater during inhalation than during exhalation. For comparison, the effect of the cardiac phase was examined, with the expectation that discrimination accuracy would be higher when the stimuli were presented during systole than during diastole. It was also hypothesized that the amplitudes of ERPs elicited by the stimuli would be greater during systole than during diastole. As expected, the results indicated that fear discrimination accuracy was higher during inhalation than exhalation and during systole than diastole. However, this was not the case for contrast discrimination. No differences in ERPs were observed between respiratory phases in either task. These results suggest that natural breathing in through the nose facilitates the discrimination of emotional stimuli, possibly via subcortical processes.

The integration of yoga breathing techniques in cognitive behavioral therapy for post-traumatic stress disorder: A pragmatic randomized controlled trial

Introduction

In trauma-focused Cognitive Behavioral Therapy (TF-CBT), stabilization techniques are used before confrontation ones to increase stress/affect tolerance and thus effectiveness of CBT. This study investigated the effects of pranayama, meditative yoga breathing and breath holding techniques, as a complimentary stabilization technique in patients with post-traumatic stress disorder (PTSD).

Methods

Seventy-four PTSD-patients (84% female, 44.2 ± 13 years) were randomized to receive either pranayama at the beginning of each TF-CBT session or TF-CBT alone. The primary outcome was self-reported PTSD severity after 10 sessions of TF-CBT. Secondary outcomes included quality of life, social participation, anxiety, depression, distress tolerance, emotion regulation, body awareness, breath-holding duration, acute emotional reaction to stress, and adverse events (AEs). Intention-to-treat (ITT) and exploratory per-protocol (PP) analyses of covariance with 95% confidence intervals (CI) were performed.

Results

ITT analyses revealed no significant differences on primary or secondary outcomes, except for breath-holding duration in favor of pranayama-assisted TF-CBT (20.81 s, 95%CI = 13.05|28.60). PP analyses of 31 patients without AEs during pranayama revealed significantly lower PTSD severity (-5.41, 95%CI = -10.17|-0.64) and higher mental quality of life (4.89, 95%CI = 1.38|8.41) than controls. In contrast, patients with AEs during pranayama breath holding reported significantly higher PTSD severity (12.39, 95%CI = 5.08|19.71) than controls. Concurrent somatoform disorders were found to be a significant moderator of change in PTSD severity (p = 0.029).

Conclusion

In PTSD patients without concurrent somatoform disorders, the integration of pranayama into TF-CBT might reduce post-traumatic symptoms and increase mental quality of life more efficiently than TF-CBT alone. The results remain preliminary until they can be replicated by ITT analyses.

Clinical trial registration

ClinicalTrials.gov, identifier NCT03748121.

Inconclusive evidence that breathing shapes pupil dynamics in humans: a systematic review

More than 50 years ago, it was proposed that breathing shapes pupil dynamics. This widespread idea is also the general understanding currently. However, there has been no attempt at synthesizing the progress on this topic since. We therefore conducted a systematic review of the literature on how breathing affects pupil dynamics in humans. We assessed the effect of breathing phase, depth, rate, and route (nose/mouth). We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and conducted a systematic search of the scientific literature databases MEDLINE, Web of Science, and PsycInfo in November 2021. Thirty-one studies were included in the final analyses, and their quality was assessed with QualSyst. The study findings were summarized in a descriptive manner, and the strength of the evidence for each parameter was estimated following the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. The effect of breathing phase on pupil dynamics was rated as "low" (6 studies). The effect of breathing depth and breathing rate (6 and 20 studies respectively) were rated as "very low". Breathing route was not investigated by any of the included studies. Overall, we show that there is, at best, inconclusive evidence for an effect of breathing on pupil dynamics in humans. Finally, we suggest some possible confounders to be considered, and outstanding questions that need to be addressed, to answer this fundamental question. Trial registration: This systematic review has been registered in the international prospective register of systematic reviews (PROSPERO) under the registration number: CRD42022285044.

Could respiration-driven blood oxygen changes modulate neural activity?

Oxygen is critical for neural metabolism, but under most physiological conditions, oxygen levels in the brain are far more than are required. Oxygen levels can be dynamically increased by increases in respiration rate that are tied to the arousal state of the brain and cognition, and not necessarily linked to exertion by the body. Why these changes in respiration occur when oxygen is already adequate has been a long-standing puzzle. In humans, performance on cognitive tasks can be affected by very high or very low oxygen levels, but whether the physiological changes in blood oxygenation produced by respiration have an appreciable effect is an open question. Oxygen has direct effects on potassium channels, increases the degradation rate of nitric oxide, and is rate limiting for the synthesis of some neuromodulators. We discuss whether oxygenation changes due to respiration contribute to neural dynamics associated with attention and arousal.

Attention Detection by Heartbeat and Respiratory Features from Radio-Frequency Sensor

This work presents a study on users' attention detection with reference to a relaxed inattentive state using an over-the-clothes radio-frequency (RF) sensor. This sensor couples strongly to the internal heart, lung, and diaphragm motion based on the RF near-field coherent sensing principle, without requiring a tension chest belt or skin-contact electrocardiogram. We use cardiac and respiratory features to distinguish attention-engaging vigilance tasks from a relaxed, inattentive baseline state. We demonstrate high-quality vitals from the RF sensor compared to the reference electrocardiogram and respiratory tension belts, as well as similar performance for attention detection, while improving user comfort. Furthermore, we observed a higher vigilance-attention detection accuracy using respiratory features rather than heartbeat features. A high influence of the user's baseline emotional and arousal levels on the learning model was noted; thus, individual models with personalized prediction were designed for the 20 participants, leading to an average accuracy of 83.2% over unseen test data with a high sensitivity and specificity of 85.0% and 79.8%, respectively.

Neural underpinning of a respiration-associated resting-state fMRI network

Respiration can induce motion and CO2 fluctuation during resting-state fMRI (rsfMRI) scans, which will lead to non-neural artifacts in the rsfMRI signal. In the meantime, as a crucial physiologic process, respiration can directly drive neural activity change in the brain, and may thereby modulate the rsfMRI signal. Nonetheless, this potential neural component in the respiration-fMRI relationship is largely unexplored. To elucidate this issue, here we simultaneously recorded the electrophysiology, rsfMRI, and respiration signals in rats. Our data show that respiration is indeed associated with neural activity changes, evidenced by a phase-locking relationship between slow respiration variations and the gamma-band power of the electrophysiological signal recorded in the anterior cingulate cortex. Intriguingly, slow respiration variations are also linked to a characteristic rsfMRI network, which is mediated by gamma-band neural activity. In addition, this respiration-related brain network disappears when brain-wide neural activity is silenced at an isoelectrical state, while the respiration is maintained, further confirming the necessary role of neural activity in this network. Taken together, this study identifies a respiration-related brain network underpinned by neural activity, which represents a novel component in the respiration-rsfMRI relationship that is distinct from respiration-related rsfMRI artifacts. It opens a new avenue for investigating the interactions between respiration, neural activity, and resting-state brain networks in both healthy and diseased conditions.

It's about time: Linking dynamical systems with human neuroimaging to understand the brain

Most human neuroscience research to date has focused on statistical approaches that describe stationary patterns of localized neural activity or blood flow. While these patterns are often interpreted in light of dynamic, information-processing concepts, the static, local, and inferential nature of the statistical approach makes it challenging to directly link neuroimaging results to plausible underlying neural mechanisms. Here, we argue that dynamical systems theory provides the crucial mechanistic framework for characterizing both the brain's time-varying quality and its partial stability in the face of perturbations, and hence, that this perspective can have a profound impact on the interpretation of human neuroimaging results and their relationship with behavior. After briefly reviewing some key terminology, we identify three key ways in which neuroimaging analyses can embrace a dynamical systems perspective: by shifting from a local to a more global perspective, by focusing on dynamics instead of static snapshots of neural activity, and by embracing modeling approaches that map neural dynamics using "forward" models. Through this approach, we envisage ample opportunities for neuroimaging researchers to enrich their understanding of the dynamic neural mechanisms that support a wide array of brain functions, both in health and in the setting of psychopathology.

Slow yoga breathing improves mental load in working memory performance and cardiac activity among yoga practitioners

This study investigated the immediate effect of slow yoga breathing (SYB) at 6 breaths per minute (bpm) simultaneously on working memory performance and heart rate variability (HRV) in yoga practitioners. A total of 40 healthy male volunteers performed a working memory task, ‘n-back’, consisting of three levels of difficulty, 0-back, 1-back, and 2-back, separately, before and after three SYB sessions on different days. The SYB sessions included alternate nostril breathing (ANB), right nostril breathing (RNB), and breath awareness (BAW). Repeated measures analysis of variance showed a significant reduction in reaction time (ms) in 2-back condition immediately after ANB (−8%), RNB (−8%) and BAW (−5%) practices. Similarly, the accuracy was improved in the 0-back condition after RNB (4%), and in the 2-back condition after ANB (6%) and RNB (6%) practices. These results suggest that SYB practice enhances cognitive abilities (8–9%) related to memory load and improves the functioning of cardiac autonomic activity, which is required for the successful completion of mental tasks.Trial registered in the Clinical Trials Registry of India (CTRI/2018/01/011132).

Beyond mindfulness: Arousal-driven modulation of attentional control during arousal-based practices

Here we report meditative techniques, which modulate attentional control by arousal-driven influences and not by monitoring continuous thought processes as during mindfulness-related practices. We focus on Vajrayana (Tantric Buddhism) practices, during which a sequence of generation (self-visualization as a deity - Yidam) or completion with sign (inner heat -Tummo) stages necessarily precedes non-dual awareness (NDA) Tantric Mahamudra. We compared the electrocardiographic and electroencephalographic correlates of Mahamudra performed after rest (non-Tantric Mahamudra) with Mahamudra performed after Yidam (Tantric Mahamudra) in 16 highly experienced Vajrayana practitioners, 10 of whom also performed Tummo. Both Yidam and Tummo developed the state of PNS withdrawal (arousal) and phasic alertness, as reflected by HF HRV decreases and Alpha2 power increases, later neurophysiologically employed in Tantric Mahamudra. The latter led to the unique state of high cortical excitability, “non-selective” focused attention, and significantly reduced attentional control, quantified by power reductions in all frequency bands, except Theta. In contrast, similar to mindfulness-related practices, non-Tantric Mahamudra was performed in a state of PNS dominance (relaxation), tonic alertness, and active monitoring, as suggested by Alpha1 power increases and less pronounced decreases in other frequency bands. A neurobiological model of meditation is proposed, differentiating arousal-based and mindfulness-related practices.

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Arousal-based meditations involve the state of PNS withdrawal and phasic alertness.

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Top-down control during arousal-based practices is modulated by arousal.

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Mindfulness-based practices involve the state of PNS dominance and tonic alertness.

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Top-down control during mindfulness-based practices is regulated by monitoring.

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NDA practices aim at non-selectivity of attention and reduction of top-down control.

Breathing Rhythm and Pattern and Their Influence on Emotion

Breathing is a vital rhythmic motor behavior with a surprisingly broad influence on the brain and body. The apparent simplicity of breathing belies a complex neural control system, the breathing central pattern generator (bCPG), that exhibits diverse operational modes to regulate gas exchange and coordinate breathing with an array of behaviors. In this review, we focus on selected advances in our understanding of the bCPG. At the core of the bCPG is the preBötzinger complex (preBötC), which drives inspiratory rhythm via an unexpectedly sophisticated emergent mechanism. Synchronization dynamics underlying preBötC rhythmogenesis imbue the system with robustness and lability. These dynamics are modulated by inputs from throughout the brain and generate rhythmic, patterned activity that is widely distributed. The connectivity and an emerging literature support a link between breathing, emotion, and cognition that is becoming experimentally tractable. These advances bring great potential for elucidating function and dysfunction in breathing and other mammalian neural circuits.

Vocalization associated respiration patterns: thermography-based monitoring and detection of preparation for calling

Vocal emission requires coordination with the respiratory system. Monitoring the increase in laryngeal pressure, which is needed for vocal production, allows detection of transitions from quiet respiration to vocalization-supporting respiration. Characterization of these transitions could be used to identify preparation for vocal emission and to examine the probability of it manifesting into an actual vocal production event. Specifically, overlaying the subject's respiration with conspecific calls can highlight events of call initiation and suppression, as a means of signalling coordination and avoiding jamming. Here, we present a thermal imaging-based methodology for synchronized respiration and vocalization monitoring of free-ranging meerkats. The sensitivity of this methodology is sufficient for detecting transient changes in the subject's respiration associated with the exertion of vocal production. The differences in respiration are apparent not only during the vocal output, but also prior to it, marking the potential time frame of the respiratory preparation for calling. A correlation between conspecific calls with elongation of the focal subject's respiration cycles could be related to fluctuations in attention levels or in the motivation to reply. This framework can be used for examining the capability for enhanced respiration control in animals during modulated and complex vocal sequences, detecting ‘failed’ vocalization attempts and investigating the role of respiration cues in the regulation of vocal interactions.

Summary: A thermography-based methodology for estimating breathing traces in free-ranging meerkats detects changes in respiration associated with the preparation and with the production of vocal signals by combining respiration monitoring with audio recordings.

Reading on a smartphone affects sigh generation, brain activity, and comprehension

Electronic devices have become an indispensable part of our daily lives, while their negative aspects have been reported. One disadvantage is that reading comprehension is reduced when reading from an electronic device; the cause of this deficit in performance is unclear. In this study, we investigated the cause for comprehension decline when reading on a smartphone by simultaneously measuring respiration and brain activity during reading in 34 healthy individuals. We found that, compared to reading on a paper medium, reading on a smartphone elicits fewer sighs, promotes brain overactivity in the prefrontal cortex, and results in reduced comprehension. Furthermore, reading on a smartphone affected sigh frequency but not normal breathing, suggesting that normal breathing and sigh generation are mediated by pathways differentially influenced by the visual environment. A path analysis suggests that the interactive relationship between sigh inhibition and overactivity in the prefrontal cortex causes comprehension decline. These findings provide new insight into the respiration-mediated mechanisms of cognitive function.

Visual discrimination accuracy does not differ between nasal inhalation and exhalation when stimuli are voluntarily aligned to breathing phase

This study investigated the possible enhancement of visual discrimination accuracy by voluntarily adjusting the timing of stimulus presentation to a specific respiratory phase. Previous research has suggested that respiratory phases modulate perceptual and cognitive processing. For instance, a fearful face was identified faster when presented during nasal inhalation than during nasal exhalation, which could be related to changes in neural oscillatory activity synchronized with breathing in through one's nose. Based on such findings, the present study asked 40 young adults to perform an emotional discrimination task consisting of distinguishing fearful vs. neutral faces and a physical discrimination task consisting of distinguishing high- vs. low-contrast Gabor patches during nasal respiration. Participants presented themselves with the stimuli to be judged in a designated respiratory phase by pressing a button. It was hypothesized that fear discrimination accuracy would be higher during inhalation than exhalation if sensitivity to emotional stimuli increased during inhalation. Conversely, if overall visual sensitivity was enhanced during inhalation, the identical effect was expected for contrast discrimination. The results indicated that discrimination accuracy did not differ between inhalation and exhalation phases in either task. This result provided no evidence that the respiratory phase affected visual discrimination accuracy when people adjusted the timing of stimulus presentation to the onset of inhalation or exhalation.

A Bridge between the Breath and the Brain: Synchronization of Respiration, a Pupillometric Marker of the Locus Coeruleus, and an EEG Marker of Attentional Control State

Yogic and meditative traditions have long held that the fluctuations of the breath and the mind are intimately related. While respiratory modulation of cortical activity and attentional switching are established, the extent to which electrophysiological markers of attention exhibit synchronization with respiration is unknown. To this end, we examined (1) frontal midline theta-beta ratio (TBR), an indicator of attentional control state known to correlate with mind wandering episodes and functional connectivity of the executive control network; (2) pupil diameter (PD), a known proxy measure of locus coeruleus (LC) noradrenergic activity; and (3) respiration for evidence of phase synchronization and information transfer (multivariate Granger causality) during quiet restful breathing. Our results indicate that both TBR and PD are simultaneously synchronized with the breath, suggesting an underlying oscillation of an attentionally relevant electrophysiological index that is phase-locked to the respiratory cycle which could have the potential to bias the attentional system into switching states. We highlight the LC’s pivotal role as a coupling mechanism between respiration and TBR, and elaborate on its dual functions as both a chemosensitive respiratory nucleus and a pacemaker of the attentional system. We further suggest that an appreciation of the dynamics of this weakly coupled oscillatory system could help deepen our understanding of the traditional claim of a relationship between breathing and attention.

Mindful Coping Power: Comparative Effects on Children's Reactive Aggression and Self-Regulation

Coping Power (CP) is an evidence-based preventive intervention for youth with disruptive behavior problems. This study examined whether Mindful Coping Power (MCP), a novel adaptation which integrates mindfulness into CP, enhances program effects on children’s reactive aggression and self-regulation. A pilot randomized design was utilized to estimate the effect sizes for MCP versus CP in a sample of 102 child participants (fifth grade students, predominantly low-middle income, 87% Black). MCP produced significantly greater improvement in children’s self-reported dysregulation (emotional, behavioral, cognitive) than CP, including children’s perceived anger modulation. Small to moderate effects favoring MCP were also observed for improvements in child-reported inhibitory control and breath awareness and parent-reported child attentional capacity and social skills. MCP did not yield a differential effect on teacher-rated reactive aggression. CP produced a stronger effect than MCP on parent-reported externalizing behavior problems. Although MCP did not enhance program effects on children’s reactive aggression as expected, it did have enhancing effects on children’s internal, embodied experiences (self-regulation, anger modulation, breath awareness). Future studies are needed to compare MCP and CP in a large scale, controlled efficacy trial and to examine whether MCP-produced improvements in children’s internal experiences lead to improvements in their observable behavior over time.

Mapping the functional brain state of a world champion freediver in static dry apnea

Voluntary apnea showcases extreme human adaptability in trained individuals like professional free divers. We evaluated the psychological and physiological adaptation and the functional cerebral changes using electroencephalography (EEG) and functional Magnetic Resonance Imaging (fMRI) to 6.5 min of dry static apnea performed by a world champion free diver. Compared to resting state at baseline, breath holding was characterized by increased EEG power and functional connectivity in the alpha band, along with decreased delta band connectivity. fMRI connectivity was increased within the default mode network (DMN) and visual areas but decreased in pre- and postcentral cortices. While these changes occurred in regions overlapping with cerebral signatures of several meditation practices, they also display some unique features that suggest an altered somatosensory integration. As suggested by self-reports, these findings could reflect the ability of elite free divers to create a state of sensory dissociation when performing prolonged apnea.

"BreaThink": breathing affects production and perception of quantities

Cognition is shaped by signals from outside and within the body. Following recent evidence of interoceptive signals modulating higher-level cognition, we examined whether breathing changes the production and perception of quantities. In Experiment 1, 22 adults verbally produced on average larger random numbers after inhaling than after exhaling. In Experiment 2, 24 further adults estimated the numerosity of dot patterns that were briefly shown after either inhaling or exhaling. Again, we obtained on average larger responses following inhalation than exhalation. These converging results extend models of situated cognition according to which higher-level cognition is sensitive to transient interoceptive states.

Examining the Role of the Noradrenergic Locus Coeruleus for Predicting Attention and Brain Maintenance in Healthy Old Age and Disease: An MRI Structural Study for the Alzheimer's Disease Neuroimaging Initiative

The noradrenergic theory of Cognitive Reserve (Robertson, 2013-2014) postulates that the upregulation of the locus coeruleus-noradrenergic system (LC-NA) originating in the brainstem might facilitate cortical networks involved in attention, and protracted activation of this system throughout the lifespan may enhance cognitive stimulation contributing to reserve. To test the above-mentioned theory, a study was conducted on a sample of 686 participants (395 controls, 156 mild cognitive impairment, 135 Alzheimer's disease) investigating the relationship between LC volume, attentional performance and a biological index of brain maintenance (BrainPAD-an objective measure, which compares an individual's structural brain health, reflected by their voxel-wise grey matter density, to the state typically expected at that individual's age). Further analyses were carried out on reserve indices including education and occupational attainment. Volumetric variation across groups was also explored along with gender differences. Control analyses on the serotoninergic (5-HT), dopaminergic (DA) and cholinergic (Ach) systems were contrasted with the noradrenergic (NA) hypothesis. The antithetic relationships were also tested across the neuromodulatory subcortical systems. Results supported by Bayesian modelling showed that LC volume disproportionately predicted higher attentional performance as well as biological brain maintenance across the three groups. These findings lend support to the role of the noradrenergic system as a key mediator underpinning the neuropsychology of reserve, and they suggest that early prevention strategies focused on the noradrenergic system (e.g., cognitive-attentive training, physical exercise, pharmacological and dietary interventions) may yield important clinical benefits to mitigate cognitive impairment with age and disease.

Keeping the Breath in Mind: Respiration, Neural Oscillations, and the Free Energy Principle

Scientific interest in the brain and body interactions has been surging in recent years. One fundamental yet underexplored aspect of brain and body interactions is the link between the respiratory and the nervous systems. In this article, we give an overview of the emerging literature on how respiration modulates neural, cognitive and emotional processes. Moreover, we present a perspective linking respiration to the free-energy principle. We frame volitional modulation of the breath as an active inference mechanism in which sensory evidence is recontextualized to alter interoceptive models. We further propose that respiration-entrained gamma oscillations may reflect the propagation of prediction errors from the sensory level up to cortical regions in order to alter higher level predictions. Accordingly, controlled breathing emerges as an easily accessible tool for emotional, cognitive, and physiological regulation.

Transcutaneous Auricular Vagus Nerve Stimulation Combined With Slow Breathing: Speculations on Potential Applications and Technical Considerations

OBJECTIVES

Transcutaneous auricular vagus nerve stimulation (taVNS) is a relatively novel noninvasive neurostimulation method that is believed to mimic the effects of invasive cervical VNS. It has recently been suggested that the effectiveness of taVNS can be enhanced by combining it with controlled slow breathing. Slow breathing modulates the activity of the vagus nerve and is used in behavioral medicine to decrease psychophysiological arousal. Based on studies that examine the effects of taVNS and slow breathing separately, this article speculates on some of the conditions in which this combination treatment may prove effective. Furthermore, based on findings from studies on the optimization of taVNS and slow breathing, this article provides guidance on how to combine taVNS with slow breathing.

MATERIALS AND METHODS

A nonsystematic review.

RESULTS

Both taVNS and slow breathing are considered promising add-on therapeutic approaches for anxiety and depressive disorders, chronic pain, cardiovascular diseases, and insomnia. Therefore, taVNS combined with slow breathing may produce additive or even synergistic beneficial effects in these conditions. Studies on respiratory-gated taVNS during spontaneous breathing suggest that taVNS should be delivered during expiration. Therefore, this article proposes to use taVNS as a breathing pacer to indicate when and for how long to exhale during slow breathing exercises.

CONCLUSIONS

Combining taVNS with slow breathing seems to be a promising hybrid neurostimulation and behavioral intervention.

Temporal Relations between Cortical Network Oscillations and Breathing Frequency during REM Sleep

Nasal breathing generates a rhythmic signal which entrains cortical network oscillations in widespread brain regions on a cycle-to-cycle time scale. It is unknown, however, how respiration and neuronal network activity interact on a larger time scale: are breathing frequency and typical neuronal oscillation patterns correlated? Is there any directionality or temporal relationship? To address these questions, we recorded field potentials from the posterior parietal cortex of mice together with respiration during REM sleep. In this state, the parietal cortex exhibits prominent θ and γ oscillations while behavioral activity is minimal, reducing confounding signals. We found that the instantaneous breathing frequency strongly correlates with the instantaneous frequency and amplitude of both θ and γ oscillations. Cross-correlograms and Granger causality revealed specific directionalities for different rhythms: changes in θ activity precede and Granger-cause changes in breathing frequency, suggesting control by the functional state of the brain. On the other hand, the instantaneous breathing frequency Granger causes changes in γ frequency, suggesting that γ is influenced by a peripheral reafference signal. These findings show that changes in breathing frequency temporally relate to changes in different patterns of rhythmic brain activity. We hypothesize that such temporal relations are mediated by a common central drive likely to be located in the brainstem.

Brain Structure and Functional Connectivity Correlate with Psychosocial Development in Contemplative Practitioners and Controls

Jane Loevinger’s theory of adult development, termed ego development (1966) and more recently maturity development, provides a useful framework for understanding the development of the self throughout the lifespan. However, few studies have investigated its neural correlates. In the present study, we use structural and functional magnetic resonance imaging (MRI) to investigate the neural correlates of maturity development in contemplative practitioners and controls. Since traits possessed by individuals with higher levels of maturity development are similar to those attributed to individuals at advanced stages of contemplative practice, we chose to investigate levels of maturity development in meditation practitioners as well as matched controls. We used the Maturity Assessment Profile (MAP) to measure maturity development in a mixed sample of participants composed of 14 long-term meditators, 16 long-term yoga practitioners, and 16 demographically matched controls. We investigated the relationship between contemplative practice and maturity development with behavioral, seed-based resting state functional connectivity, and cortical thickness analyses. The results of this study indicate that contemplative practitioners possess higher maturity development compared to a matched control group, and in addition, maturity development correlates with cortical thickness in the posterior cingulate. Furthermore, we identify a brain network implicated in theory of mind, narrative, and self-referential processing, comprising the posterior cingulate cortex, dorsomedial prefrontal cortex, temporoparietal junction, and inferior frontal cortex, as a primary neural correlate.

Is a Mask That Covers the Mouth and Nose Free from Undesirable Side Effects in Everyday Use and Free of Potential Hazards?

Many countries introduced the requirement to wear masks in public spaces for containing SARS-CoV-2 making it commonplace in 2020. Up until now, there has been no comprehensive investigation as to the adverse health effects masks can cause. The aim was to find, test, evaluate and compile scientifically proven related side effects of wearing masks. For a quantitative evaluation, 44 mostly experimental studies were referenced, and for a substantive evaluation, 65 publications were found. The literature revealed relevant adverse effects of masks in numerous disciplines. In this paper, we refer to the psychological and physical deterioration as well as multiple symptoms described because of their consistent, recurrent and uniform presentation from different disciplines as a Mask-Induced Exhaustion Syndrome (MIES). We objectified evaluation evidenced changes in respiratory physiology of mask wearers with significant correlation of O2 drop and fatigue (p < 0.05), a clustered co-occurrence of respiratory impairment and O2 drop (67%), N95 mask and CO2 rise (82%), N95 mask and O2 drop (72%), N95 mask and headache (60%), respiratory impairment and temperature rise (88%), but also temperature rise and moisture (100%) under the masks. Extended mask-wearing by the general population could lead to relevant effects and consequences in many medical fields.

The metronome response task for measuring mind wandering: Replication attempt and extension of three studies by Seli et al

Science requires replicable tools to measure its intended constructs. Attention research has developed tools that have been used in mind-wandering research, but mind-wandering measures often rely on response-inhibition, which introduces speed-accuracy trade-offs that may conflate errors for mind-wandering. We sought to replicate three studies that used an improved mind-wandering measure: the Metronome Response Task (MRT). In a large (N=300) multisite sample, the primary MRT finding was replicated, showing that continuous rhythmic response time variability reliably predicted self-reported mind-wandering. Our findings also show previously undetected differences between intentional and unintentional mind-wandering. While previously reported mediators (motivation) and moderators (confidence) did not replicate, additional covariates add predictive value and additional constructs (e.g., boredom, effort) demonstrate convergent validity. The MRT is useful for inducing and measuring mind-wandering and provides an especially replicable tool. The MRT's measurement of attention could support future models of the complete cycle of sustained attention.

Promoting Mental Health and Psychological Thriving in University Students: A Randomized Controlled Trial of Three Well-Being Interventions

This study aimed to address the decline in mental health on U.S. university campuses by examining the effects of three interventions. University students suffer from high levels of anxiety, depression, and suicide. Counseling centers on university campuses are struggling to meet increased demand. The cost to students and universities could be buffered by offering preventative, psychoeducational, and skill-building training programs that promote mental health and psychological thriving. To date, the research literature has not yielded systematically evaluated and recommendable preventative mental health and well-being programs for university students. In a registered, randomized controlled trial, 131 university students were either placed in a non-intervention control group (N = 47) or received training in one of three 30-hour, eight-week semester-long well-being programs: SKY Campus Happiness ("SKY"; N = 29), Foundations of Emotional Intelligence ("EI"; N = 21) or Mindfulness-Based Stress Reduction ("MBSR"; N = 34). Compared to the control group and controlling for variance of baseline measurements and multiple comparisons, SKY Campus Happiness showed the greatest impact, benefiting six outcomes: depression, stress, mental health, mindfulness, positive affect and social connectedness. EI benefited one outcome: mindfulness. The MBSR group showed no change. Delivering SKY or EI to university students may be a cost-effective and efficient way to proactively and preventatively address mental health for university students and reduce the financial strain on universities.

An Anti-hyperventilation Instruction Decreases the Drop in End-tidal CO2 and Symptoms of Hyperventilation During Breathing at 0.1 Hz

Breathing at a frequency of around 0.1 Hz is widely used in basic research and in applied psychophysiology because it strongly increases fluctuations in the cardiovascular system and affects psychological functioning. Volitional control of breathing often leads to hyperventilation among untrained individuals, which may produce aversive symptoms and alter the psychological and physiological effects of the paced breathing. The present study investigated the effectiveness of a brief anti-hyperventilation instruction during paced breathing at a frequency of 0.1 Hz. Forty-six participants were randomly assigned to one of two groups: a group given an anti-hyperventilation instruction and a control group without such an instruction. The instruction asked participants to avoid excessively deep breathing and to breathe shallowly and naturally. Participants performed the breathing task for 10 min. Hyperventilation was measured by partial pressure of end-tidal CO₂ (PetCO₂); furthermore, symptoms of hyperventilation, feeling of air hunger, task difficulty, and affective state were measured by self-report. The results showed that paced breathing without instruction decreased PetCO₂ by 5.21 mmHg and that the use of the anti-hyperventilation instruction reduced the drop in PetCO₂ to 2.7 mmHg. Symptoms of hyperventilation were lower in the group with the anti-hyperventilation instruction. Neither the feeling of air hunger nor task difficulty were affected by the instruction. There were no significant effects of the instruction on affective state. The present study indicates that a brief anti-hyperventilation instruction may be used to decrease drop in PetCO₂ and symptoms of hyperventilation during breathing at 0.1 Hz and that the instruction is well tolerated.

Respiratory regulation & interactions with neuro-cognitive circuitry

It is increasingly being recognized that active control of breathing - a key aspect of ancient Vedic meditative practices, can relieve stress and anxiety and improve cognition. However, the underlying mechanisms of respiratory modulation of neurophysiology are just beginning to be elucidated. Research shows that brainstem circuits involved in the motor control of respiration receive input from and can directly modulate activity in subcortical circuits, affecting emotion and arousal. Meanwhile, brain regions involved in the sensory aspects of respiration, such as the olfactory bulb, are like-wise linked with wide-spread brain oscillations; and perturbing olfactory bulb activity can significantly affect both mood and cognition. Thus, via both motor and sensory pathways, there are clear mechanisms by which brain activity is entrained to the respiratory cycle. Here, we review evidence gathered across multiple species demonstrating the links between respiration, entrainment of brain activity and functional relevance for affecting mood and cognition. We also discuss further linkages with cardiac rhythms, and the potential translational implications for biorhythm monitoring and regulation in neuropsychiatric disorders.

Hypothesis: Pulmonary Afferent Activity Patterns During Slow, Deep Breathing Contribute to the Neural Induction of Physiological Relaxation

Control of respiration provides a powerful voluntary portal to entrain and modulate central autonomic networks. Slowing and deepening breathing as a relaxation technique has shown promise in a variety of cardiorespiratory and stress-related disorders, but few studies have investigated the physiological mechanisms conferring its benefits. Recent evidence suggests that breathing at a frequency near 0.1 Hz (6 breaths per minute) promotes behavioral relaxation and baroreflex resonance effects that maximize heart rate variability. Breathing around this frequency appears to elicit resonant and coherent features in neuro-mechanical interactions that optimize physiological function. Here we explore the neurophysiology of slow, deep breathing and propose that coincident features of respiratory and baroreceptor afferent activity cycling at 0.1 Hz entrain central autonomic networks. An important role is assigned to the preferential recruitment of slowly-adapting pulmonary afferents (SARs) during prolonged inhalations. These afferents project to discrete areas in the brainstem within the nucleus of the solitary tract (NTS) and initiate inhibitory actions on downstream targets. Conversely, deep exhalations terminate SAR activity and activate arterial baroreceptors via increases in blood pressure to stimulate, through NTS projections, parasympathetic outflow to the heart. Reciprocal SAR and baroreceptor afferent-evoked actions combine to enhance sympathetic activity during inhalation and parasympathetic activity during exhalation, respectively. This leads to pronounced heart rate variability in phase with the respiratory cycle (respiratory sinus arrhythmia) and improved ventilation-perfusion matching. NTS relay neurons project extensively to areas of the central autonomic network to encode important features of the breathing pattern that may modulate anxiety, arousal, and attention. In our model, pronounced respiratory rhythms during slow, deep breathing also support expression of slow cortical rhythms to induce a functional state of alert relaxation, and, via nasal respiration-based actions on olfactory signaling, recruit hippocampal pathways to boost memory consolidation. Collectively, we assert that the neurophysiological processes recruited during slow, deep breathing enhance the cognitive and behavioral therapeutic outcomes obtained through various mind-body practices. Future studies are required to better understand the physio-behavioral processes involved, including in animal models that control for confounding factors such as expectancy biases.

Defining the Rhythmogenic Elements of Mammalian Breathing

Breathing's remarkable ability to adapt to changes in metabolic, environmental, and behavioral demands stems from a complex integration of its rhythm-generating network within the wider nervous system. Yet, this integration complicates identification of its specific rhythmogenic elements. Based on principles learned from smaller rhythmic networks of invertebrates, we define criteria that identify rhythmogenic elements of the mammalian breathing network and discuss how they interact to produce robust, dynamic breathing.