Autonomic Activity Research Articles

Electrophysiological correlates of why humans deviate from rational decision-making: A registered replication study.

In contrast to rational choice theory predicting humans to optimize expected utilities of choices, humans deviate from rational behavior in decision-making paradigms. Hewig etal. (2011) explored affective correlates of decision-making in the ultimatum game (UG) and the dictator game (DG). They found that feedback-related negativity (FRN), subjective valence ratings, and autonomic nervous system activity predicted rejection of monetary offers. This registered replication aimed to validate and extend these findings. Although behavioral patterns and results of subjective ratings closely matched the original study, not all psychophysiological effects were successfully replicated. Firstly, we could not replicate the reported effects of autonomic nervous system activity. Secondly, a quadratic instead of the originally proposed linear relation between the offer and the FRN emerged, possibly driven by the offer evaluation in economic games and the rewarding anticipation of successful punishment for low offers. Thirdly, P3 amplitudes mirrored the quadratic offer response pattern, generally peaking for the lowest offer. In contrast to the original study, P3 responses were larger in the UG compared with the DG. Finally, our findings indicate that participant-related higher midfrontal theta activation predicted lower acceptance behavior in the UG, with a systematic dampening effect for fairer offers. This highlights cognitive control as a crucial mechanism in economic decision-making to overcome behavioral defaults. Overall, our results conceptually support the original conclusion that decision-making in economic games is non-rational and dependent on the objective situation as well as emotional and neural markers, though not precisely as suggested by Hewig etal. (2011).

(Invited) Electrodermal Activity Sensing at Scale

Electrodes have emerged as powerful tools for sensing various physiological signals, paving the way for a new era of wearable consumer devices that offer in situ measurement and analysis. Electrodermal activity (EDA) sensors are used for evaluating autonomic nervous system activity, wherein changes in EDA are associated with physiological excitation reflecting stress, arousal, and emotional changes. The Fitbit Sense 2 and Pixel Watch 2 are two wearable commercial devices that passively measure EDA using wrist-facing electrodes powering a stress management feature. Descriptive findings of the Fitbit Sense 2 across 10 million hours of continuous EDA data collected from over 16,000 people are herein reported, including real-time population response to Thanksgiving 2022 and the 2023 Super Bowl.

Momentary autonomic engagement during parent-adolescent conflict: Coping as a moderator of associations with emotions.

Regulatory efforts are hypothesized to affect associations between emotions and physiology (i.e., concordance) to facilitate adaptive functioning. Assessing the role of coping on physiological-emotional concordance during ecologically relevant scenarios can elucidate whether concordance can serve as a biomarker of risk or resilience. The present study assessed self-reported coping as a moderator of minute-to-minute associations between autonomic nervous system activity and emotions (i.e., physiological-emotional concordance) in caregivers (N = 97) and adolescents (N = 97; ages 10-15) during a dyadic conflict task. Models included physiological variables (sympathetic, skin conductance level [SCL]; and parasympathetic, respiratory sinus arrhythmia [RSA]) and their interaction (SCL × RSA) as predictors of emotions, with coping variables as moderators. Caregivers' use of primary control coping (e.g., problem solving and emotional expression) and secondary control coping (e.g., cognitive reappraisal and acceptance) use in response to family stress predicted more positive emotional experiences during the laboratory conflict task. Adolescents' use of secondary control coping moderated the SCL-emotion association, such that increases in momentary SCL were associated with more positive emotion ratings for youth reporting higher secondary control coping. For youth who report more adaptive trait-level coping skills, momentary changes in SCL may reflect active engagement and attentiveness to facilitate more positive emotional experiences. Findings advance our understanding of the interrelationships between physiological responses and psychological experiences during relevant, interactive scenarios. Autonomic responses are differentially related to affective states depending on the coping strategies that adolescents employ, suggesting that concordance may be associated with intervention targets (i.e., coping skills).

Autonomic assessment at the intersection of psychosocial and gastrointestinal health.

Wearable technology is increasingly used in clinical practice and research to monitor functional gastrointestinal symptoms and mental health. This article explores the potential of wearable sensors to enhance the understanding of the autonomic nervous system (ANS), particularly its role in linking psychological and gastrointestinal function. The ANS, facilitates brain-gut communication and is responsive to psychosocial conditions. It is implicated in disorders related to psychological stress and gut-brain interaction. Wearable technology enables tracking of the ANS in daily life, offering complementary and alternative methods from traditional lab-based measures. This review places focus on autonomic metrics such as respiratory sinus arrhythmia, vagal efficiency, and electrodermal activity as well as self-reports of autonomic symptoms. Potential applications include use of wearable sensors for tracking autonomic activity in disorder of gut-brain interaction such as cyclic vomiting syndrome, in which ANS dysregulation may be triggered by psychosocial factors. Considerations for data interpretation and contextualization are addressed, acknowledging challenges such as situational confounders of ANS activity and accuracy of wearable devices.

Circadian disruptions and their role in the development of hypertension.

Circadian fluctuations in physiological setpoints are determined by the suprachiasmatic nucleus (SCN) which exerts control over many target structures within and beyond the hypothalamus via projections. The SCN, or central pacemaker, orchestrates synchrony between the external environment and the internal circadian mechanism. The resulting cycles in hormone levels and autonomic nervous system (ANS) activity provide precise messages to specific organs, adjusting, for example, their sensitivity to approaching hormones or metabolites. The SCN responds to both photic (light) and non-photic input. Circadian patterns are found in both heart rate and blood pressure, which are linked to daily variations in activity and autonomic nervous system activity. Variations in blood pressure are of great interest as several cardiovascular diseases such as stroke, arrhythmias, and hypertension are linked to circadian rhythm dysregulation. The disruption of normal day-night cycles, such as in shift work, social jetlag, or eating outside of normal hours leads to desynchronization of the central and peripheral clocks. This desynchronization leads to disorganization of the cellular processes that are normally driven by the interactions of the SCN and photic input. Here, we review autonomic system function and dysfunction due to regulation and interaction between different cardiorespiratory brain centers and the SCN, as well as social, lifestyle, and external factors that may impact the circadian control of blood pressure.

Assessing Children's Autonomic Nervous System Activity During Structured Tasks: A Feasibility and Reliability Study in Ghana.

The significance of physiological regulation in relation to behavioral and emotional regulation is well documented, but primarily in economically advantaged contexts. Few studies have been conducted in low- and middle-income countries. We investigated the feasibility and reliability of measuring autonomic nervous system (ANS) activity and behavior during challenge tasks in 30 children aged 8-10 years in Ghana during two visits, 1 week apart. Completeness of ANS data ranged from 80% to 100% across all tasks. There was low-to-moderate test-retest reliability of video mood induction (VMI) emotion ratings and balloon analog risk task (BART) pumps (r=0.34-0.52). VMI elicited higher targeted emotion ratings in Visit 2 than Visit 1. Respiratory sinus arrhythmia (RSA) was higher, and pre-ejection period (PEP) was longer at Visit 2 than Visit 1 for baseline and both tasks. RSA was higher at baseline than during the VMI anger scene at Visit 1, whereas PEP was shorter at baseline than during all VMI emotion scenes at Visit 2. RSA was higher at baseline than during BART at both visits. In conclusion, ANS data collection within evocative and arousing challenge tasks was feasible in Ghana, and the tasks were generally reliable and effective in eliciting target emotions and risk-taking behavior in this sample.

Hypertension and Device-Based Therapies for Resistant Hypertension: An Up-to-Date Review.

Hypertension is the most prevalent modifiable risk factor associated with cardiovascular mortality. The World Health Organization (WHO) estimates that hypertension directly or indirectly causes the death of at least nine million people globally every year. The number of people living with hypertension (blood pressure (BP) of ≥140 mmHg systolic or ≥90 mmHg diastolic or on medication) doubled between 1990 and 2019, from 650 million to 1.3 billion. Despite a plethora of antihypertensivedrugs widely available, a sizable part of the antihypertensive population stays uncontrolled. The unmet need of controlling BP in this population may be addressed, in part, by developing new drugs and devices/procedures to treat hypertension and its comorbidities. Several device-based approaches have been introduced to lower BP, and most of these strategies aim to modulate autonomic nervous system activity. Importantly, when considering a device-based treatment, each patient's underlying pathophysiology is considered, and the procedural risks are weighed against the cardiovascular risk attributed to the elevated BP.In November 2023, the FDA approved two renal denervation (RDN) devices. This manuscript discusses current interventional devices and procedures recently approved (RDN) and others in the clinical testing stage for arterial hypertension intervention or management.As we list below, all others have shown promising results and are being evaluated on a larger clinical trial.The new device-based classes are as follows: catheter-based RDN, baroreflex amplification, arteriovenous (AV) malformation, carotid body (CB) ablation, pacemaker-based cardiac neuromodulation, electro-acupuncture, and deep brain stimulation. Baroreflex amplification uses peripheral neuromodulation, while AV malformation leverages AV anastomosis. CB ablation modulates chemoreceptors, and pacemaker-based neuromodulation adjusts atrioventricular intervals. Electro-acupuncture proves potential, and deep brain stimulation offers central nervous system intervention.

Hormones, autonomic nervous system activity, and criminal behavior

ABSTRACT Evidence that hormones and autonomic nervous system activity exert a joint influence on antisocial behavior suggests that they may work together to explain risk for criminal behavior. Thus, the current study explored the interactive effects of hormones (testosterone, cortisol) and ANS activity (heart rate, skin conductance) on impulsive and violent criminal behavior in a large sample of university students (n = 495). Initial analyses found positive direct associations between impulsive and violent crime and both testosterone and cortisol and a negative direct association between heart rate reactivity and impulsive and violent crime. Subsequent analyses revealed a statistically significant interaction between testosterone and heart rate in association with impulsive and violent criminal behavior. The positive association between testosterone and crime became statistically significant at −.29 standard deviations below the mean (HR = 76.44) and grew stronger as heart rate decreased from this point. The interaction between testosterone and heart rate remains statistically significant after the inclusion of controls for constructs that feature prominently in contemporary criminological theories. Other interactions between hormones and ANS activity were present but were not consistent across alternative model specifications.

Glutamatergic and purinergic transmitters and astrocyte modulation in the synaptic transmission in the NTS of rats exposed to short-term sustained hypoxia.

There is evidence that astrocytes modulate synaptic transmission in the nucleus tractus solitarius (NTS) interacting with glutamatergic and purinergic mechanisms. Here, using in situ working heart-brainstem preparations, we evaluated the involvement of astrocyte and glutamatergic/purinergic neurotransmission in the processing of autonomic and respiratory pathways in the NTS of control and rats exposed to sustained hypoxia (SH). Baseline autonomic and respiratory activities and the responses to chemoreflex activation (KCN) were evaluated before and after microinjections of fluorocitrate (FCt, an astrocyte metabolic inhibitor), kynurenic acid, and pyridoxalphosphate-6-azophenyl-2',4'-disulfonate (PPADS) (nonselective antagonists of glutamatergic and purinergic receptors) into the rostral aspect of the caudal commissural NTS. FCt had no effects on the baseline parameters evaluated but reduced the bradycardic response to chemoreflex activation in SH rats. FCt combined with kynurenic acid and PPADS in control rats reduced the baseline duration of expiration, which was attenuated after SH. FCt produced a large increase in PN frequency discharge in control rats, which was reduced after SH, indicating a reduction in the astrocyte modulation after SH. The data show that 1) the bradycardic component of the peripheral chemoreflex is reduced in SH rats after astrocytes inhibition, 2) the inhibition of astrocytes in the presence of double antagonists in the NTS affects the modulation of baseline duration of expiration in control but not in SH rats, and 3) the autonomic and respiratory responses to chemoreflex activation are mediated by glutamatergic and purinergic receptors in the rostral aspect of the caudal commissural NTS.NEW & NOTEWORTHY Our findings indicate that the neurotransmission of autonomic and respiratory components of the peripheral chemoreflex in the nucleus tractus solitarius (NTS) is mediated by glutamatergic and purinergic mechanisms and reveal a selective involvement of NTS astrocytes in controlling the chemoreflex parasympathetic response in rats exposed to sustained hypoxia (SH) and the baseline duration of expiration mainly in control rats, indicating a selective role for astrocytes modulation in the NTS of control and SH rats.

Psychophysiological and interpersonal effects of parallel group crafting: a multimodal study using EEG and ECG

In occupational therapy, crafts and groups are used as therapeutic tools, but their electrophysiological effects have not been well described. This study aimed to investigate the effects of group crafting on the physiological synchrony (PS) of dyadic heartbeats and on the autonomic activity and electroencephalogram (EEG) of individuals. In this cross-sectional study, individuals’ EEG and dyadic electrocardiogram (ECG) were measured during the task in a variety of conditions. The three conditions were alone, parallel, nonparallel. Autonomic activity from the subjects’ ECG, PS from the dyadic ECG, and current source density from exact Low Resolution Brain Electromagnetic Tomography (eLORETA) from subjects’ EEG were analyzed. Measurements from 30 healthy young adults showed that the parallel condition significantly increased subjects' parasympathetic activity and dyadic PS. Parallel condition and frontal midline theta influenced parasympathetic activity, whereas parasympathetic activity was not associated with PS. Dyadic lag value were correlated with frontal delta, beta, and gamma activity. The results suggest that crafting in parallel groups increases parasympathetic activity and PS through different mechanisms, despite the absence of direct interaction. They also explain the electrophysiological evidence for the use of crafts and groups in psychiatric occupational therapy, such as increased relaxation and PS.

Renal autonomic dynamics in hypertension: how can we evaluate sympathetic activity for renal denervation?

This review explores the various pathophysiological factors influencing antihypertensive effects, involving the regulation of vascular resistance, plasma volume, cardiac function, and the autonomic nervous system, emphasizing the interconnected processes regulating blood pressure (BP). The kidney's pivotal role in BP control and its potential contribution to hypertension is complicated but important to understand the effective mechanisms of renal denervation (RDN), which may be a promising treatment for resistant hypertension. Excessive stimulation of the sympathetic nervous system or the renin-angiotensin-aldosterone system (RAAS) can elevate BP through various physiological changes, contributing to chronic hypertension. Renal sympathetic efferent nerve activation leads to elevated norepinephrine levels and subsequent cascading effects on vasoconstriction, renin release, and sodium reabsorption. RDN reduces BP in resistant hypertension by potentially disrupting sensory afferent nerves, decreasing feedback activation to the central nervous system, and reducing efferent sympathetic nerve activity in the heart and other structures. RDN may also modulate central sympathetic outflow and inhibit renal renin-angiotensin system overactivation. While evidence for RDN efficacy in hypertension is increasing, accurate patient selection becomes crucial, considering complex interactions that vary among patients. This review also discusses methods to evaluate autonomic nerve activity from the golden standard to new potential examination for finding out optimization in stimulation parameters or rigorous patient selection based on appropriate biomarkers.

Effect of remimazolam and propofol anesthesia on autonomic nerve activities during Le Fort I osteotomy under general anesthesia: blinded randomized clinical trial.

This study evaluated the effect of remimazolam and propofol on changes in autonomic nerve activity caused by surgical stimulation during orthognathic surgery, using power spectrum analysis of blood pressure variability (BPV) and heart rate variability (HRV), and their respective associations with cardiovascular fluctuations. A total of 34 patients undergoing Le Fort I osteotomy were randomized to the remimazolam (Group R, 17 cases) or propofol (Group P, 17 cases) groups. Observables included the low-frequency component of BPV (BPV LF; index of vasomotor sympathetic nerve activity), high-frequency component of HRV (HRV HF; index of parasympathetic nerve activity), balance index of the low- and high-frequency components of HRV (HRV LF/HF; index of sympathetic nerve activity), heart rate (HR), and systolic blood pressure (SBP). Four observations were made: (1) baseline, (2) immediately before down-fracture, (3) down-fracture, and (4) 5 min after down-fracture. Data from each observation period were compared using a two-way analysis of variance with a mixed model. A Bonferroni multiple comparison test was performed in the absence of any interaction. One-way analysis of variance followed by Tukey's multiple comparisons test was performed when a significant interaction was observed between time and group, with P < 0.05 indicating statistical significance. Evaluation of autonomic nerve activity in comparison with baseline during down-fracture showed a significant increase in BPV LF (P < 0.001), an increasing trend in HRV LF/HF in Group P, and an increasing trend in HRV HF in Group R. There were no significant differences in HR or SBP between the two groups. During down-fracture of Le Fort I osteotomy, sympathetic nerve activity was predominant with propofol anesthesia, and parasympathetic nerve activity was predominant with remimazolam anesthesia.

Disrupted coherence between autonomic activation and emotional expression in individuals at clinical high risk for psychosis.

Landmark studies have shown decreased coherence between different emotion response systems (e.g., physiology and facial expressions) in people with psychosis. However, while there is good evidence to suggest broad signs of affective dysfunction (e.g., blunting of facial expression) in the critical clinical high-risk (CHR) state, it is not clear whether these signs fit into a broader pattern of decoupling. This is in part due to there being no studies to date with this population that include a dyadic interaction. The current laboratory-based dyadic interaction study examined whether there is decreased coherence in CHR between autonomic physiology, as indexed by heart rate, and facial expressions of emotion, assessed by automated facial expressions analysis. The study included 145 individuals consisting of 34 CHR-partner and 41 control-partner pairs who completed clinical interviews and engaged in three naturalistic 10-min conversations while their physiology and expressions were continuously monitored. Compared to controls, CHR youth showed decreased coherence between heart rate and positive (t = 4.09) and negative (t = -7.90) facial expressions. Across CHR and control youth, greater severity of psychosis risk symptoms was related to lower coherence between heart rate and positive (t = 3.97-11.69) and neutral expressions (t = 0.06-4.98), and a change in the direction of the relationship between heart rate and negative expression intensity (t = 7.88-10.60). These findings provide the first evidence for changes in coherence between physiology and facial expressions of emotion in CHR individuals, with larger changes in coherence relating to greater general psychotic-like symptom severity. This evidence may be leveraged to identify targets for early diagnosis and intervention. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Improving Prefrontal Oxygenation and Cardiac Autonomic Activity Following Meditation: A Functional Near-Infrared Spectroscopy (fNIRS) Study.

The empirical evidence explicitly demonstrates that meditation practice enhances both brain functions and mental well-being. A meditative relaxation approach called the mind sound resonance technique (MSRT) has shown promising effects on children, adolescents, and people with psychological illnesses. This study aimed to investigate the effects of MSRT practice on brain hemodynamics, heart rate variability (HRV), mindfulness, and anxiety levels in college students. Fifty volunteers in all genders (females, n = 30; males, n = 20) aged between 19 and 30 years were chosen from an educational institute and allocated into two groups, i.e., MSRT (n = 25) and supine rest (SR; n = 25). Enrolled participants were measured cerebral hemodynamics and HRV before, during, and after the MSRT or SR practice. The self-reported assessments including state anxiety and mindfulness were assessed before and after the intervention. The results demonstrated that practicing MSRT significantly improved oxygenation (p < 0.05) in the right prefrontal cortex (PFC) and increased low-frequency (LF) (p < 0.05) and decreased high-frequency (HF) (p < 0.05) component of HRV when compared to the baseline. The between-group analysis showed a significant difference between MSRT and SR in the standard deviation of the normal-to-normal (SDNN)(p < 0.05) component of HRV. These crumbs of evidence imply that MSRT sessions may foster the development of anxiety-related coping skills by elevating mindfulness, promoting PFC oxygenation, and modulating HRV in MSRT practitioners.

Dynamic Bandwidth Allocation for Collaborative Multi-Robot Systems Based on Task Execution Measures

Multi-robot systems (MRSs) is a growing field of research that focuses on the collaboration of multiple robots to achieve a common global objective. Managing these systems poses several challenges, including coordination, task allocation, and communication. Among these challenges, a major area of focus is devising an effective communication scheme that ensures robots’ cooperation and adapts to varying conditions during task execution. In this paper, we develop a novel communication management framework tailored for MRSs, specifically addressing dynamic bandwidth distribution in networked teleoperated robotic systems. The algorithm is combined with semi-autonomous formation control based on the Artificial Potential Fields (APF) algorithm, which allows each individual robot to avoid local obstacles autonomously and tries to maintain a desired formation with its neighbors, while the operator is in charge of high-level control only. Common Dynamic Bandwidth Allocation (DBA) algorithms allocate bandwidth to different units based on network conditions and requirements. On the other hand, our proposed DBA scheme dynamically distributes the available bandwidth on communication streams based on factors related to task execution and system performance. In specific, bandwidth is allocated in a way that adapts to changes occurring in the system’s environment and its internal state, including the effect of the autonomous action taken by the path planner on the MRS and the performance of the controller of each individual robot. By addressing the limitations of existing approaches through shaping the communication behavior of the MRS based on performance measures, our proposed algorithm offers a promising solution for improving the performance and efficiency of MRSs. The proposed scheme is tested through simulations on a group of six unmanned aerial vehicles (UAVs) in the Robot Operating System (ROS)-Gazebo simulation environment. The obtained results show the scheme’s capability for enhancing the robotic system’s performance while significantly reducing bandwidth consumption. Experimental testing on two mobile robots further demonstrates the effectiveness of the proposed scheme.

중등학교에서의 학생자치 경험에 대한 내러티브 연구

This study concentrates on students’ narratives regarding their autonomous experiences. Their voices will dynamically reveal the characteristics of student autonomy and its practical limitations. The objective of this study is to vividly share the viewpoints and opinions of students who had directly participated in autonomous activities. To achieve this objective, research participants with ample experience in autonomous activities were chosen. A semi-structured in-depth interview was conducted on two research participants with whom the researcher had formed a rapport, and the content was thoroughly described and interpreted. The results are shown below. First, students’ autonomous activities are led by a small number of the student council executives. Second, teachers’ ‘opportunism’ becomes the worst obstacle in autonomous activities of students. It is not teachers’ indifference but their non-cooperative and conservative attitudes that have a negative influence on autonomous activities. Third, students’ autonomous activities cannot extend to activities that ‘transform’ the school structure. Fourth, students voluntarily show efforts to expand their autonomous activities. To overcome practical limitations in schools, they seek solidarity forces who support their opinions. The representative body of such a solidarity force was the ‘parent association’. The results of this research deduced the following implications for future student autonomous activities. First, it is necessary to reduce the gap in students’ experiences in autonomous activities. Second, teachers in charge of student councils must enhance their understanding of educational autonomy and democracy. Third, these teachers must be provided with an environment where they can be fully immersed in autonomous learning activities of students. Fourth, voluntary participation of the student council executives must be ensured in the school council.

Intrinsic Motivational States Can Be Classified by Non-Contact Measurement of Autonomic Nervous System Activation and Facial Expressions

Motivation is a primary driver of goal-directed behavior. Therefore, the development of cost-effective and easily applicable systems to objectively quantify motivational states is needed. To achieve our goal, this study investigated the feasibility of classifying high- and low-motivation states by machine learning based on a diversity of features obtained by non-contact measurement of physiological responses and facial expression analysis. A random forest classifier with feature selection yielded modest success in the classification of high- and low-motivation states. Further analysis linked high-motivation states to the indices of autonomic nervous system activation reflective of reduced sympathetic activation and stronger, more intense expressions of happiness. The performance of motivational state classification systems should be further improved by incorporating different varieties of non-contact measurements.

Cerebral homeostasis and orthostatic responses in residents of the highest city in the world

Permanent residence at high-altitude and chronic mountain sickness (CMS) may alter the cerebrovascular homeostasis and orthostatic responses. Healthy male participants living at sea-level (LL; n = 15), 3800 m (HL3800m; n = 13) and 5100 m (HL5100m; n = 17), respectively, and CMS highlanders living at 5100 m (n = 31) were recruited. Middle cerebral artery mean blood flow velocity (MCAv), cerebral oxygen delivery (CDO2), mean blood pressure (MAP), heart rate variability and spontaneuous cardiac baroreflex sensitivity (cBRS) were assessed while sitting, initial 30 s and after 3 min of standing. Cerebral autoregulation index (ARI) was estimated (ΔMCAv%baseline)/ΔMAP%baseline) in response to the orthostatic challenge. Altitude and CMS were associated with hypoxemia and elevated hemoglobin concentration. While sitting, MCAv and LFpower negatively correlated with altitude but were not affected by CMS. CDO2 remained preserved. BRS was comparable across all altitudes, but lower with CMS. Within initial 30 s of standing, altitude and CMS correlated with a lesser ΔMAP while ARI remained unaffected. After 3 min standing, MCAv, CDO2 and cBRS remained preserved across altitudes. The LF/HF ratio increased in HL5100m compared to LL and HL3800m from sitting to standing. In contrary, CMS showed blunted autonomic nervous activation in responses to standing. Despite altitude- and CMS-associated hypoxemia, erythrocytosis and impaired blood pressure regulation (CMS only), cerebral homeostasis remained overall preserved.

Analysis of heart rate variability and anthropometric measurements to compare obesity classes II and III in patients undergoing bariatric surgery

Introduction: obesity is an important public health problem worldwide. It is believed that obese candidates for bariatric surgery present cardiac autonomic dysfunction and that weight reduction achieved through surgical treatment of obesity may promote improvement in autonomic nervous system activity, minimizing cardiovascular risks. Objective: thus, the objective of this study is to assess the impact of surgical bariatric weight reduction on HRV and on anthropometric measurements (BMI, WHtR, and WC) comparing obesity classes II and III. Method: the study included 25 obese individuals who underwent a preoperative assessment. Anthropometric measurements and heart rate varability (HRV) were collected preoperatively. The participants were then divided into two groups: obesity class II and obesity class III (class II: BMI from 35 to 39 k/m2, and class III: BMI from &gt; 40 kg/m2). Thirty days after surgery, a postoperative assessment was performed and the data were compared. Results: our results confirm that both class II and III obesity groups presented altered HRV preoperatively and that the participants in the obesity II group showed a statistically significant increase in the HRV index when compared to the obesity III group, through the mean RR, PNN50, SNS, and stress index. Conclusion: the findings confirmed the important contribution that bariatric surgery makes to improving metabolic health and lowering important obesity indices. The varying alterations in heart rate variability indicate subtle advantages concerning autonomic function, especially for individuals classified as obese II

Pupil light reflex in young elite athletes: autonomic nervous system activity and viscoelastic properties.

Introduction: The pupil light reflex (photomotor reflex) has a duration of 3.5s and is a highly reproducible measurement. Conventionally, the autonomic nervous system (ANS) activity evaluated by this reflex does not consider the viscoelasticity of the iris muscles. This study aims to detect differences in reflex autonomic activity in a supine position with parameters derived from the Kelvin-Voigt viscoelastic model in two distinct groups of elite athletes. Method: Groups formed using a dendrogram analysis based on basal autonomic activity assessed with heart rate variability. Heart rate variability was measured, and the photomotor reflex was modeled. Results: The model showed a high degree of adjustment to the photomotor reflex (r2 = 0.99 ± 0.01). The impulse 3, an indicator of reflex sympathetic activity, revealed a significantly higher activity (ρ ≤ 0.05) in the [sympa/para]+ group compared to the [sympa/para]⁻ group. This result was further supported by a greater relative total redilation amplitude (ρ ≤ 0.05) and a shorter duration of 75% redilation (ρ ≤ 0.01). Finally, the relative total redilation amplitude exhibited a significant correlation with the linear stiffness constant (ρ ≤ 0.001) and the maximum redilation speed with restoring force (ρ ≤ 0.001). Discussion: These results indicate that (i) the photomotor reflex can detect an alteration of the reflex autonomic activity specific to each of the two branches of the ANS (ii) the viscoelastic properties of the iris muscles play a significant role in the energy storage-restitution mechanisms during the photomotor reflex. This approach could allow athletes to benefit from reduced time spent in the analysis of ANS activity, potentially making it an almost daily and automated process.