Autonomic Nervous System Responses Research Articles

Autonomic nervous system responses to hypo- and hyperglycemia in type 2 diabetes and prediabetes.

Previous research points to a role of the brain in the regulation of glucose and pathogenesis of type 2 diabetes (T2D) via modulation of counter-regulatory hormone secretion and activity in the autonomic nervous system (ANS). The aim of this study was to investigate glucose-dependent responses of catecholamines and ANS activity in individuals with T2D, prediabetes (PD) and normoglycemia (NG). Cross-sectional. Individuals with T2D (n=19, 7 men, HbA1c 49 mmol/mol), prediabetes (PD, n=18, 8 men) and normoglycemia (NG, n=17, 3 men) underwent one stepwise hyperinsulinemic-euglycemic-hypoglycemic and one hyperglycemic clamp with repeated measurements of catecholamines, symptoms, heart rate variability (HRV) and hemodynamics. The hypoglycemic response of adrenaline was augmented in T2D and PD vs NG (both p<0.05) and there was a strong association with insulin resistance (p<0.05 for M-value). In relation to achieved glucose levels in both clamps, noradrenaline exhibited a steeper rise during hypoglycemia in T2D vs NG and PD (both p<0.05). There were trends toward more marked autonomic hypoglycemic symptoms in T2D vs PD and NG. By contrast, insulin resistance was associated with attenuated responses of heart rate and HRV-indices PLF and PHF at the target glucose plateau of 2.7 mmol/l (p<0.05), independent of BMI and HbA1c. Alterations in glucose-dependent responses of counter-regulatory hormones and the autonomic nervous system appear before, and probably contribute to, the onset of T2D. Together with other reported alterations in neuroendocrine pathways, the findings suggest that a maladaptation of the brain's responses to glucose fluctuations is important in T2D progression.

Emotional contagion to vocal smile revealed by combined pupil reactivity and motor resonance

The interplay between the different components of emotional contagion (i.e. emotional state and facial motor resonance), both during implicit and explicit appraisal of emotion, remains controversial. The aims of this study were (i) to distinguish between these components thanks to vocal smile processing and (ii) to assess how they reflect implicit processes and/or an explicit appraisal loop. Emotional contagion to subtle vocal emotions was studied in 25 adults through motor resonance and Autonomic Nervous System (ANS) reactivity. Facial expressions (fEMG: facial electromyography) and pupil dilation were assessed during the processing and judgement of artificially emotionally modified sentences. fEMG revealed that Zygomaticus major was reactive to the perceived valence of sounds, whereas the activity of Corrugator supercilii reflected explicit judgement. Timing analysis of pupil dilation provided further insight into both the emotional state and the implicit and explicit processing of vocal emotion, showing earlier activity for emotional stimuli than for neutral stimuli, followed by valence-dependent variations and a late judgement-dependent increase in pupil diameter. This innovative combination of different electrophysiological measures shed new light on the debate between central and peripherical views within the framework of emotional contagion.

Negative auditory hallucinations are associated with increased activation of the defensive motivational system in schizophrenia

Auditory hallucinations (AH) are the most common symptom of psychosis. The voices people hear make comments that are benign or even encouraging, but most often voices are threatening and derogatory. Negative AH are often highly distressing and contribute to suicide risk and violent behavior. Biological mechanisms underlying the valence of voices (i.e., positive, negative, neutral) are not well delineated. In the current study, we examined whether AH voice valence was associated with increased activation of the Defensive Motivational System, as indexed by central and autonomic system response to unpleasant stimuli. Data were evaluated from two studies that used a common symptom rating instrument, the Psychotic Symptom Rating Scale (PSY-RATS), to measure AH valence. Participants included outpatients diagnosed with SZ. Tasks included: Study 1: Trier Social Stress Task while heart rate was recorded via electrocardiography (N = 27); Study 2: Passive Viewing Task while participants were exposed to pleasant, unpleasant, and neutral images from the International Affective Picture System (IAPS) library while eye movements, pupil dilation, and electroencephalography were recorded (N = 25). Results indicated that negative voice content was significantly associated with: 1) increased heart rate during an acute social stressor, 2) increased pupil dilation to unpleasant images, 3) higher neural reactivity to unpleasant images, and 4) a greater likelihood of having bottom-up attention drawn to unpleasant stimuli. Findings suggest that negative AH are associated with greater Defensive Motivational System activation in terms of central and autonomic nervous system response.

INDICATORS OF OCULOMOTOR ACTIVITY AND CEREBRAL HEMODYNAMICS IN STUDENTS WITH DIFFERENT TYPES OF AUTONOMIC NERVOUS SYSTEM REACTIVITY IN COGNITIVE TASK PERFORMANCE

Background. The current stage of human development is characterized by high dynamics of knowledge accumulation, acceleration of social and technical development. The need to study psychophysiological characteristics of cognitive activity with time limitation increases under these conditions. Time limit can make activity more efficient or less effective. Purpose. To study indicators of oculomotor activity and cerebral hemodynamics of students with different types of autonomic nervous system reactivity during cognitive activity. Materials and methods. The study involved 110 students of the Northern (Arctic) Federal University named after M.V. Lomonosov took part in the study (average age of students 19.0±0.5 years). To identify specific features of ensuring cognitive activity in different time conditions, the type of reactivity of the autonomic nervous system (ANS) was determined in the subjects using the VNS-Spectrum computer complex (Neurosoft). Students performed cognitive tasks without and with time limits. At the same time, eye movements were recorded using the stationary binocular eye tracking system iView X™ RED, 500 Hz, and cerebral hemodynamic parameters were recorded using the Reo-Spectrum 2 hardware and software complex (Neurosoft). The efficiency of cognitive activity of the participants was also assessed. Statistical analysis was performed using the application package IBM SPSS Statistics 22.0. Results. Students with different types of reactivity of the autonomic nervous system had different effectiveness of cognitive activity without time limitation and with time limitation. Students with a sympathotonic type of autonomic reactivity had a higher result in processing visual information under time pressure. These students had more stable statistical relationships between the parameters of oculomotor activity and cerebral hemodynamics. Representatives with a vagotonic type of reactivity of the autonomic nervous system had the lowest rates of success in cognitive activity. These students showed less stable structure of statistical relationships between oculomotor activity and cerebral hemodynamics Conclusion. General and specific changes in cerebral hemodynamics and oculomotor activity, features of the effectiveness of cognitive activity under time constraints in young people with different types of autonomic nervous system reactivity were identified.

Autonomous nervous system responses to environmental-level exposure to 5G's first deployed band (3.5GHz) in healthy human volunteers.

Following the global progressive deployment of 5G networks, considerable attention has focused on assessing their potential impact on human health. This study aims to investigate autonomous nervous system changes by exploring skin temperature and electrodermal activity (EDA) among 44 healthy young individuals of both sexes during and after exposure to 3.5GHz antenna-emitted signals, with an electrical field intensity ranging from 1 to 2V/m. The study employed a randomized, cross-over design with triple-blinding, encompassing both 'real' and 'sham' exposure sessions, separated by a maximum interval of 1week. Each session comprised baseline, exposure and postexposure phases, resulting in the acquisition of seven runs. Each run initiated with a 150s segment of EDA recordings stimulated by 10 repeated beeps. Subsequently, the collected data underwent continuous decomposition analysis, generating specific indicators assessed alongside standard metrics such as trough-to-peak measurements, global skin conductance and maximum positive peak deflection. Additionally, non-invasive, real-time skin temperature measurements were conducted to evaluate specific anatomical points (hand, head and neck). The study suggests that exposure to 3.5GHz signals may potentially affect head and neck temperature, indicating a slight increase in this parameter. Furthermore, there was a minimal modulation of certain electrodermal metrics after the exposure, suggesting a potentially faster physiological response to auditory stimulation. However, while the results are significant, they remain within the normal physiological range and could be a consequence of an uncontrolled variable. Given the preliminary nature of this pilot study, further research is needed to confirm the effects of 5G exposure.

Investigating the effects of artificial baroreflex stimulation on pain perception: A comparative study in no-pain and chronic low back pain individuals.

The autonomic nervous system (ANS) and pain exhibit a reciprocal relationship, where acute pain triggers ANS responses, whereas resting ANS activity can influence pain perception. Nociceptive signalling can also be altered by 'top-down' processes occurring in the brain, brainstem and spinal cord, known as 'descending modulation'. By employing the conditioned pain modulation (CPM) paradigm, we previously revealed a connection between reduced low-frequency heart rate variability and CPM. Individuals with chronic pain often experience both ANS dysregulation and impaired CPM. Baroreceptors, which contribute to blood pressure and heart rate variability regulation, may play a significant role in this relationship, although their involvement in pain perception and their functioning in chronic pain have not been sufficiently explored. In the present study, we combined artificial 'baroreceptor stimulation' in both pressure pain and CPM paradigms, seeking to explore the role of baroreceptors in pain perception and descending modulation. In total, 22 individuals with chronic low back pain (CLBP) and 29 individuals with no-pain (NP) took part in the present study. We identified a differential modulation of baroreceptor stimulation on pressure pain between the groups of NP and CLBP participants. Specifically, NP participants perceived less pain in response to baroreflex activation, whereas CLBP participants exhibited increased pain sensitivity. CPM scores were associated with baseline measures of baroreflex sensitivity in both CLBP and NP participants. Our data support the importance of the baroreflex in chronic pain and a possible mechanism of dysregulation involving the interaction between the ANS and descending pain modulation. KEY POINTS: Baroreflex stimulation has different effects on pressure pain in participants with chronic pain compared to matched individuals with no-pain. Baroreceptor activation decreases pain in participants with no-pain but increases pain perception in participants with chronic pain. Baroreflex sensitivity is associated with conditioned pain modulation in both groups of chronic pain and no-pain participants. The reactivity of the baroreflex during autonomic stress demonstrated a positive correlation with Pain Trait scores in participants with chronic back pain.

Evaluating the Effects of Different Cognitive Tasks on Autonomic Nervous System Responses: Implementation of a High-Precision, Low-Cost Complementary Method.

We developed a low-cost, user-friendly complementary research tool to evaluate autonomic nervous system (ANS) activity at varying levels of cognitive workload. This was achieved using visual stimuli as cognitive tasks, administered through a specially designed computer-based test battery. To assess sympathetic stress responses, skin conductance response (SCR) was measured, and electrocardiograms (ECG) were recorded to evaluate heart rate variability (HRV), an indicator of cardiac vagal tone. Twenty-five healthy adults participated in the study. SCR and ECG recordings were made during both tonic and phasic phases using a computer-based system designed for visual stimuli. Participants performed a button-pressing task upon seeing the target stimulus, and the relationship between reaction time (RT) and cognitive load was evaluated. Analysis of the data showed higher skin conductance levels (SCLs) during tasks compared to baseline, indicating successful elicitation of sympathetic responses. RTs differed significantly between simple and cognitive tasks, increasing with mental load. Additionally, significant changes in vagally mediated HRV parameters during tasks compared to baseline highlighted the impact of cognitive load on the parasympathetic branch of the ANS, thereby influencing the brain-heart connection. Our findings indicate that the developed research tool can successfully induce cognitive load, significantly affecting SCL, RTs, and HRV. This validates the tool's effectiveness in evaluating ANS responses to cognitive tasks.

Impact of Serial Casting on Autonomic Nervous System Responses during Virtual Reality Tasks in Children with Cerebral Palsy: A Pilot Study Comparing Orthoses and Barefoot Conditions.

Cerebral palsy (CP) is a group of movement disorders that impair posture and mobility, often leading to spasticity and joint contractures. Interventions like serial casting are commonly used to improve joint mobility and manage spasticity in children with CP. However, its effects on the autonomic nervous system (ANS) remain unclear. This study aimed to evaluate the effects of serial casting and ankle-foot orthoses (AFOs) on ANS responses during a virtual reality (VR) standing task, comparing these interventions with a barefoot condition. Thirty children with CP were randomized into three groups (n = 10 per group): serial casting, AFOs, and barefoot. Heart rate variability (HRV) was used to assess ANS responses across three phases: seated rest, VR task, and recovery. The results showed that the serial casting group exhibited higher sympathetic activity during rest compared to the other groups, but had a reduced sympathetic response during the VR task. Additionally, the serial casting group displayed a more pronounced parasympathetic rebound during recovery, similar to the orthoses and barefoot groups. While serial casting provides essential joint stability, it alters ANS response patterns, leading to heightened sympathetic activation at rest, without providing significant improvements in ANS behavior during physical activity.

The role of changes in peer victimization from elementary to high school and autonomic reactivity on adolescent reactive aggression.

The goals of the present study were to investigate links between changes in peer victimization from elementary to high school and adolescent reactive aggression (Goal 1), whether heightened autonomic nervous system (ANS) reactivity to social and nonsocial stress increases risk for adolescent reactive aggression (Goal 2), and whether increased ANS reactivity strengthens the association between changes in victimization and adolescent reactive aggression (Goal 3). Participants included 145 adolescents (Mage = 16; 54% female; 76% European American, 13% African American, 11% Latino American, 7% Asian American, 5% of mixed race or ethnicity; 60% with family incomes of $100,000 or greater). We collected self-report data in elementary (Time 1 [T1]); (Time 2 [T2]); middle (Time 3 [T3]); and high school (Time 4 [T4]) to assess victimization. At T4, we measured self-reported reactive and proactive aggression, and ANS reactivity (preejection period [PEP], respiratory sinus arrhythmia [RSA]) to peer rejection and nonsocial frustration. More positive victimization slope over time (meaning both less decreasing slopes and increasing slopes) predicted greater adolescent reactive, but not proactive aggression (Goal 1). Greater RSA augmentation to peer rejection and more PEP reactivity to nonsocial frustration predicted more reactive, but not proactive aggression (Goal 2). The link between victimization slope and reactive aggression emerged only for adolescents exhibiting RSA augmentation to peer rejection (marginal; Goal 3). (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Heart rate variability in horses with and without severe equine asthma.

Equine asthma in severe form (severe equine asthma [sEA]) shares remarkable similarities with human asthma. Human studies detected changes in the autonomic nervous system function in asthmatic patients based on heart rate variability (HRV) analysis. Observational study. To investigate the relationship between sEA and HRV in horses. Twenty horses diagnosed with sEA and 20 asymptomatic (non-sEA) horses were investigated. SEA horses showed clinical signs. The RR intervals of the ECG were recorded for 1 h at rest between 9 AM and 11 AM using a heart rate (HR) monitor. HRV data were calculated using Kubios software. Parameters recorded for the sEA and non-sEA groups were compared using one-way MANOVA model. The significance level was set at α = 0.05. SD2 (mean 99.6 ± SD 25.3 vs. 42.5 ± 17.1), SDNN (82.7 ± 20.7 vs. 41.3 ± 14.3), TINN (398.1 ± 104.9 vs. 209.3 ± 71.9), SD2/SD1 ratio (1.7 ± 0.2 vs. 1.1 ± 0.3), Total power (4740.2 ± 1977.9 vs. 1503.0 ± 1179.3), LF (2415.3 ± 1072.4 vs. 707.4 ± 649.9), SD1 (60.9 ± 15.9 vs. 39.2 ± 14.1), RMSSD (86.0 ± 22.6 vs. 55.3 ± 19.8) and HF (1575.8 ± 902.5 vs. 578.1 ± 491.1) were lower in sEA horses compared with the non-sEA horses (p < 0.01 for each variable). SD2, SDNN, TNN, the SD2/SD1 ratio and Total power showed the greatest discriminatory power in differentiating the sEA and non-sEA groups. Small sample size. Our findings indicate that like humans, asthmatic horses show an overall reduction in autonomic control. A relative increase of the parasympathetic modulation of the heart was also observed. After further investigations, HRV measurement might be a non-invasive approach to monitor autonomic nervous system responses of sEA horses.

Autonomic nervous system and viscera-related responses to manual therapy: A narrative overview

BackgroundManual therapy (MT) has long-held that it physiologically impacts autonomic nervous system (ANS) and viscera-related function. This narrative review is intended to serve as a consolidated interdisciplinary resource of original studies related to physiological effects of MT as it relates to the ANS for MT clinicians and researchers new to this MT-related topic. ObjectiveThis review seeks to identify ANS and viscera-related physiological responses to MT interventions using search terms commonly used by chiropractic, massage, osteopathic, physical therapy, and structural integration clinicians and to provide a quick reference resource of original MT-related studies investigating ANS effects. MethodsFor this interdisciplinary review, the search was limited to the largest and most commonly used database (PubMed) between years 2000 and 2024, with a focus on direct ANS-related physiological outcomes. Unlike systematic reviews, assessment of scientific rigor and potential bias of included articles was beyond the scope and purpose of the current work. ResultsOriginal MT-related studies provide mixed evidence with regards to immediate and/or short term ANS and/or viscera-related responses on blood pressure, heart rate variability, skin conductance/temperature, respiratory and lymphatic changes. ConclusionsThis review identified a large number of MT and ANS-related original research in PubMed. Careful study of original MT-related research is needed with particular attention focused on the standardization of MT methodological approaches, appropriate controls, study design, appropriate populations, MT techniques, and anatomical site delivery so as to design more rigorous studies in order to arrive at definitive conclusions regarding direct effects of MT on the ANS.

Orthostatic testing for heart rate and heart rate variability monitoring in exercise science and practice.

Orthostatic testing, involving the transition from different body positions (e.g., from lying or sitting position to an upright or standing position), offers valuable insights into the autonomic nervous system (ANS) functioning and cardiovascular regulation reflected through complex adjustments in, e.g., measures of heart rate (HR) and heart rate variability (HRV). This narrative review explores the intricate physiological mechanisms underlying orthostatic stress responses and evaluates its significance for exercise science and sports practice. Into this matter, active orthostatic testing (e.g., active standing up) challenges the cardiovascular autonomic function in a different way than a passive tilt test. It is well documented that there is a transient reduction in blood pressure while standing up, leading to a reflex increase in HR and peripheral vasoconstriction. After that acute response systolic and diastolic blood pressures are usually slightly increased compared to supine lying body position. The ANS response to standing is initiated by instantaneous cardiac vagal withdrawal, followed by sympathetic activation and vagal reactivation over the first 25-30 heartbeats. Thus, HR increases immediately upon standing, peaking after 15-20 beats, and is less marked during passive tilting due to the lack of muscular activity. Standing also decreases vagally related HRV indices compared to the supine position. In overtrained endurance athletes, both parasympathetic and sympathetic activity are attenuated in supine and standing positions. Their response to standing is lower than in non-overtrained athletes, with a tendency for further decreased HRV as a sign of pronounced vagal withdrawal and, in some cases, decreased sympathetic excitability, indicating a potential overtraining state. However, as a significant main characteristic, it could be noted that additional pathophysiological conditions consist in a reduced responsiveness or counter-regulation of neural drive in ANS according to an excitatory stimulus, such as an orthostatic challenge. Hence, especially active orthostatic testing could provide additional information about HR(V) reactivity and recovery giving valuable insights into athletes' training status, fatigue levels, and adaptability to workload. Measuring while standing might also counteract the issue of parasympathetic saturation as a common phenomenon especially in well-trained endurance athletes. Data interpretation should be made within intra-individual data history in trend analysis accounting for inter-individual variations in acute responses during testing due to life and physical training stressors. Therefore, additional measures (e.g., psychometrical scales) are required to provide context for HR and HRV analysis interpretation. However, incidence of orthostatic intolerance should be evaluated on an individual level and must be taken into account when considering to implement orthostatic testing in specific subpopulations. Recommendations for standardized testing procedures and interpretation guidelines are developed with the overall aim of enhancing training and recovery strategies. Despite promising study findings in the above-mentioned applied fields, further research, thorough method comparison studies, and systematic reviews are needed to assess the overall perspective of orthostatic testing for training monitoring and fine-tuning of different populations in exercise science and training.

Pupillometry and autonomic nervous system responses to cognitive load and false feedback: an unsupervised machine learning approach.

Pupil dilation is controlled both by sympathetic and parasympathetic nervous system branches. We hypothesized that the dynamic of pupil size changes under cognitive load with additional false feedback can predict individual behavior along with heart rate variability (HRV) patterns and eye movements reflecting specific adaptability to cognitive stress. To test this, we employed an unsupervised machine learning approach to recognize groups of individuals distinguished by pupil dilation dynamics and then compared their autonomic nervous system (ANS) responses along with time, performance, and self-esteem indicators in cognitive tasks. Cohort of 70 participants were exposed to tasks with increasing cognitive load and deception, with measurements of pupillary dynamics, HRV, eye movements, and cognitive performance and behavioral data. Utilizing machine learning k-means clustering algorithm, pupillometry data were segmented to distinct responses to increasing cognitive load and deceit. Further analysis compared clusters, focusing on how physiological (HRV, eye movements) and cognitive metrics (time, mistakes, self-esteem) varied across two clusters of different pupillary response patterns, investigating the relationship between pupil dynamics and autonomic reactions. Cluster analysis of pupillometry data identified two distinct groups with statistically significant varying physiological and behavioral responses. Cluster 0 showed elevated HRV, alongside larger initial pupil sizes. Cluster 1 participants presented lower HRV but demonstrated increased and pronounced oculomotor activity. Behavioral differences included reporting more errors and lower self-esteem in Cluster 0, and faster response times with more precise reactions to deception demonstrated by Cluster 1. Lifestyle variations such as smoking habits and differences in Epworth Sleepiness Scale scores were significant between the clusters. The differentiation in pupillary dynamics and related metrics between the clusters underlines the complex interplay between autonomic regulation, cognitive load, and behavioral responses to cognitive load and deceptive feedback. These findings underscore the potential of pupillometry combined with machine learning in identifying individual differences in stress resilience and cognitive performance. Our research on pupillary dynamics and ANS patterns can lead to the development of remote diagnostic tools for real-time cognitive stress monitoring and performance optimization, applicable in clinical, educational, and occupational settings.

Effect of classical music on light-plane anaesthesia and analgesia in dogs subjected to surgical nociceptive stimuli

The objectives of this prospective, randomized, blinded, crossover, experimental study were to detect the potential anaesthetic- and analgesic-sparing effects of classical music provided to dogs undergoing skin surgery, and to investigate the role of substance P as an intraoperative pain indicator. Twenty dogs were included, each subjected to three different treatments: Chopin music, Mozart music and no music. They were premedicated with acepromazine, butorphanol and meloxicam and anaesthetized with propofol and isoflurane. Fentanyl was used as rescue analgesia. The anaesthetic depth was monitored by using the bispectral index along with standard anaesthetic monitoring, and autonomic nervous system responses were used to monitor the adequacy of analgesia. Furthermore, measurements of substance P serum concentration were carried out. Dogs exposed to music required less isoflurane and fentanyl. Furthermore, a statistically significant effect of time on substance P concentration was observed regardless of exposure to music, and there was a significant interaction effect between different timepoints and the type of acoustic stimulus. Classical music seems to have an isoflurane and fentanyl sparing effect on dogs undergoing minor surgery. Following surgical stimulation, the serum substance P concentration increases rapidly, and thus appears to be a potentially useful pain indicator.

Exploring the Relationship Between Voice Disorders in Indian Classical Music and the Guru-Shishya Parampara Through an Understanding of the Autonomic Nervous System

ABSTRACT The Guru-Shishya Parampara (GSP), translated as the teacher-student tradition, is a lineage-based oral tradition in Indian Classical Music (ICM). This study explores the relationship between GSP’s traditional obedience-authority dynamic and prevalent voice disorders experienced by ICM practitioners. Combining Constructivist Grounded Theory document analysis and a narrative literature review, the research investigates how disciplinarian tendencies and power differentials in authoritarian implementations of the GSP may contribute to or reinforce voice disorders resulting from psychological strain. Adopting the Indigenous Research Paradigm, the study prioritizes insights from ICM practitioners’ lived experiences within the cultural context of ICM within the analysis. A narrative review of existing literature on the links between autonomic nervous system responses associated with psychological stressors and voice disorders is discussed to further understand the impact of authoritarian GSPs on singers’ voices. Literature on compassion is additionally explored to discuss potential solutions to address the identified issues. Through this approach, the study offers insights into the complex interactions between power dynamics, psychological strain, and voice disorders within obedience-expectant GSPs, aiming to contribute to the development of effective interventions, highlighting that which already exists within ICM culture, to promote vocal health and overall well-being in this ancient and culturally significant tradition.

Heart Rate Variability in Military Pilots During Flight: A Scoping Review.

Piloting an aircraft is a complex multitasking activity that involves managing information in a nonautomatic way and generates a high workload (psychological, cognitive, and physical) for the pilot. The excess of these demands can result in decreased performance and may impair flight safety. Heart rate variability (HRV) has been used in recent studies as a method to investigate operator's workload in complex environments. This measure can assess the stress and recovery ability of the autonomic nervous system. However, a better understanding of flight influence on the pilot's autonomic modulation is necessary. Therefore, this scoping review aims to systematically map the studies related to changes in the autonomic modulation in military pilots during flight, in order to characterize their workload at different times and flight profiles. A literature search was conducted using MEDLINE (by PubMed), SCOPUS, and LILACS databases. Recent records (2002-2022) that analyzed HRV in military pilots during flight were included. Meanwhile, studies in which piloting activity was not performed were excluded. The study was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline extension for Scoping Reviews and the Updated Methodological Guidance for the Conduct of Scoping Reviews. A total of 298 records were obtained, of which 19 were included in the scoping review. The studies analyzed flights performed in high- and low-performance aircrafts, helicopters, and flight simulators, using time domain, frequency domain, and nonlinear HRV indices. Real and simulated flights produced significant autonomic changes. Some flights elicited autonomic nervous system responses that persisted up to 5 h after landing. During real flight, the most sensitive indices for identifying variations in pilot workload were root mean square of successive differences between normal heartbeats, standard deviation of interbeat interval of normal sinus beat (SDNN), ratio of low-frequency to high-frequency power, and Poincaré plot standard deviation perpendicular to the line of identity (SD1), whereas the interbeat interval (RR), SDNN, SD1, and Poincaré plot standard deviation along the line of identity (SD2) were the most sensitive indices when comparing segments of simulated flight with different levels of difficulty. This scoping review provided insight into the influence of flight on autonomic modulation in military pilots. Some key themes were highlighted: Increased sympathetic activity during flight, sensibility of different domains of HRV to flight demands, and autonomic changes during recovery time. Future research efforts may allow us to enhance the understanding of pilot's workload limits and to elucidate the optimal postflight recovery time.

Pupil contagion variation with gaze, arousal, and autistic traits

Pupillary contagion occurs when one’s pupil size unconsciously adapts to the pupil size of an observed individual and is presumed to reflect the transfer of arousal. Importantly, when estimating pupil contagion, low level stimuli properties need to be controlled for, to ensure that observations of pupillary changes are due to internal change in arousal rather than the external differences between stimuli. Here, naturalistic images of children’s faces depicting either small or large pupils were presented to a group of children and adolescents with a wide range of autistic traits, a third of whom had been diagnosed with autism. We examined the extent to which pupillary contagion reflects autonomic nervous system reaction through pupil size change, heart rate and skin conductance response. Our second aim was to determine the association between arousal reaction to stimuli and degree of autistic traits. Results show that pupil contagion and concomitant heart rate change, but not skin conductance change, was evident when gaze was restricted to the eye region of face stimuli. A positive association was also observed between pupillary contagion and autistic traits when participants’ gaze was constrained to the eye region. Findings add to a broader understanding of the mechanisms underlying pupillary contagion and its association with autism.

Elevated unanticipated acoustic startle reactivity in dyslexia.

People with dyslexia, a neurodevelopmental disorder of reading, are highly attuned to the emotional world. Compared with their typically developing peers, children with dyslexia exhibit greater autonomic nervous system reactivity and facial behaviour to emotion- and empathy-inducing film clips. Affective symptoms, such as anxiety, are also more common in children with dyslexia than in those without. Here, we investigated whether the startle response, an automatic reaction that lies at the interface of emotion and reflex, is elevated in dyslexia. We measured facial behaviour, electrodermal reactivity (a sympathetic nervous system measure) and emotional experience in response to a 100 ms, 105 dB unanticipated acoustic startle task in 30 children with dyslexia and 20 comparison children without dyslexia (aged 7-13) who were matched on age, sex and nonverbal reasoning. Our results indicated that the children with dyslexia had greater total facial behaviour and electrodermal reactivity to the acoustic startle task than the children without dyslexia. Across the sample, greater electrodermal reactivity during the startle predicted greater parent-reported anxiety symptoms. These findings contribute to an emerging picture of heightened emotional reactivity in dyslexia and suggest accentuated sympathetic nervous system reactivity may contribute to the elevated anxiety that is often seen in this population.

Autonomic nervous system and endocrine system response to upper or lower cervical spine mobilization in males with persistent post-concussion symptoms: a proof-of-concept trial

ABSTRACT Introduction The peripheral stress response, consisting of the autonomic nervous system (ANS) and hypothalamic pituitary adrenal-axis (HPA-axis), functions to maintain homeostasis in response to stressors. Cervical spine manual therapy has been shown to differentially modulate the stress response in healthy populations. No study has investigated whether cervical spine mobilizations can differentially modulate the stress response in individuals with persistent post-concussion symptoms (PPCS), a population characterized by a dysfunctional stress response. Methods A randomized, controlled, parallel design trial was performed to investigate whether upper or lower cervical spine mobilization can differentially modulate components of the stress response in individuals with PPCS. The outcomes were salivary cortisol (sCOR) concentration (primary) and the HRV metric, rMSSD, measured with a smartphone application (secondary). Nineteen males diagnosed with PPCS, aged 19–35, were included. Participants were randomly assigned into either intervention group, upper (n = 10) or lower (n = 9) cervical spine mobilization. Each outcome was collected at different time points, pre- and post-intervention. Statistical analyses were performed using the Friedman’s Two-Way ANOVA, Mann-Whitney U test, and Wilcoxon Signed Rank Test. Results There was a statistically significant within-group reduction in sCOR concentration 30 minutes following lower cervical spine mobilizations and statistically significant within-group increase in rMSSD 30 minutes following upper cervical spine mobilizations. Conclusion The results of this trial provide preliminary evidence for cervical spine mobilizations to differentially modulate components of the stress response at specific time points. Understanding the mechanisms of the effect of cervical spine mobilizations on the stress response provides a novel rationale for selecting cervical spine mobilizations to rehabilitate individuals with PPCS.

Acute Autonomic Nervous System Response to Direct Sacral Nerve Root Stimulation in Lower Urinary Tract Dysfunction: A New Approach to Understand the Mechanism of Action of Sacral Nerve Modulation.

Our goal was to assess acute autonomic nervous system (ANS) response to direct sacral nerve root (SNR) stimulation in the context of lower urinary tract dysfunction. In this retrospective monocentric study, patients undergoing 2-stage sacral nerve modulation for overactive bladder, nonobstructive urinary retention, or chronic bladder pain syndrome between March 2022 and June 2023 were analyzed. A standardized stimulation protocol was applied during the lead implantation, each of the 4 contact points being sequentially stimulated at the amplitude required to elicit anal motor response. Stimulations were labeled as StimA, StimB, StimC, and StimD, ordered by ascending order of minimum amplitude required for anal motor response. Heart rate variability parameters were collected using PhysioDoloris Monitor, and computed through the time-domain (standard deviation of normal-to-normal intervals [SDNN], root mean square of successive differences), the frequency-domain (low frequency, high frequency) and the graphical (Analgesia Nociception Index [ANI]) methods. Fifty patients were analyzed, including 35 females. Twelve patients had an underlying neurological disease. Efficacy was deemed achieved in 54% of patients. SDNN variability significantly increased during StimA to StimC, while maximum SDNN significantly increased only during StimA. ANI variability significantly increased during all 4 stimulations, while maximum ANI significantly increased only during StimA. Direct stimulation of SNR is responsible for a significant increase in ANS and relative parasympathetic nervous system activity, with a greater effect observed when the stimulation was delivered closer to the SNR. These results shed light on potential mechanisms underlying sacral nerve modulation, particularly regarding the treatment of ANS dysregulation in lower urinary tract dysfunction.