Parasympathetic Branches Research Articles

Music Modulates Autonomic Nervous System Activity in Human Fetuses.

ContextFetal Autonomic Nervous sysTem Evaluation (FANTE) is a non-invasive tool that evaluates the autonomic nervous system activity in a fetus. Autonomic nervous system maturation and development during prenatal life are pivotal for the survival and neuropsychiatric development of the baby.ObjectiveAim of the study is to evaluate the effect of music stimulation on fetal heart rate and specific parameters linked to ANS activity, in particular fetal heart rate variability.MethodsThirty-two women between the 32nd and 38th week with a singleton uncomplicated pregnancy were recruited. All FANTE data collections were acquired using a 10-derivation electrocardiograph placed on the maternal abdomen. In each session (5 min basal, 10 min with music stimulus, and 5 min post-stimulus), FANTE was registered. The music stimulus was “Clair de lune” Debussy, played through headphones on the mother’s abdomen (CTR: 31927).ResultsMusic does not change the mean value of fetal heart rate. However, indices of total fetal heart rate variability statistically increase (RRsd p = 0.037, ANNsd p = 0.039, SD2 p = 0.019) during music stimulation in comparison to the basal phase. Heart rate variability increase depends mainly on the activation of parasympathetic branches (CVI p = 0.013), meanwhile, no significant changes from basal to stimulation phase were observed for indices of sympathetic activity. All the parameters of heart rate variability and parasympathetic activity remained activated in the post-stimulus phase compared to the stimulus phase. In the post-stimulus phase, sympathetic activity resulted in a significant reduction (LFn p = 0.037).ConclusionMusic can influence the basal activity of the fetal autonomic nervous system, enhancing heart rate variability, without changing fetal heart rate mean value. Music is enabled to induce a relaxation state in a near-to-term fetus, mediated by parasympathetic activation and by a parallel sympathetic inhibition.

Autonomic modulation of chronic kidney patients on hemodialysis

Chronic kidney Disease may progress to cardiovascular complications just as much as these complications can result in further deterioration of the renal function, with dialysis as an extreme therapeutical option. Heart Rate Variability is a noninvasive method for the evaluation of sympathovagal imbalance of the heart beat control, aiding on the early detection of cardiovascular malfunctions. Our purpose was to identify heart rate variability patterns in chronic kidney disease patients undergoing hemodialysis treatment, both by linear and nonlinear analysis.Were sampled a group of 27 renal failure patients under hemodialysis care, and a control group of 21 healthy individuals. The RR intervals were captured with a Polar® device from subjects lying in supine position for 20 minutes. A total of 1000 consecutive intervals were selected, and both linear and nonlinear parameters were considered for the heart rate variability analysis. Were used Shapiro-Wilk test, Mann-Whitney test, and Spearman test. Among the findings with statistical significance, reductions were found in RMSSD and pNN50, and SD1 and SD2 indexes whereas increases in the recurrence percentage and in entropy could be observed. A significant negative correlation between age and the values of SD1 index was also found. Patients with renal failure present a lower autonomic modulation of the parasympathetic branch, as highlighted by both the linear and nonlinear analysis. The nonlinear indexes in the Chaos domain were more precise in identifying autonomic dysfunctions, can reflect more clearly the complexity of the organic systems.

B lymphocyte-derived acetylcholine limits steady-state and emergency hematopoiesis.

Autonomic nerves control organ function through the sympathetic and parasympathetic branches, which have opposite effects. In the bone marrow, sympathetic (adrenergic) nerves promote hematopoiesis; however, how parasympathetic (cholinergic) signals modulate haematopoiesis is unclear. Here we show that B lymphocytes were an important source of acetylcholine, a neurotransmitter of the parasympathetic nervous system which reduced hematopoiesis. Single cell RNA sequencing identified 9 clusters of cells that expressed the acetylcholine receptor Chrna7 in the bone marrow stem cell niche, including endothelial and mesenchymal stromal cells. Deletion of B cell-derived acetylcholine resulted in the differential expression of various genes, including Cxcl12 in LepR+ stromal cells. Pharmacologic inhibition of acetylcholine signaling increased the systemic supply of inflammatory myeloid cells in mice and patients with cardiovascular disease.

Low-input Nucleus Isolation and Multiplexing with Barcoded Antibodies of Mouse Sympathetic Ganglia for Single-nucleus RNA Sequencing.

The cardiac autonomic nervous system is crucial in controlling cardiac function, such as heart rate and cardiac contractility, and is divided into sympathetic and parasympathetic branches. Normally, there is a balance between these two branches to maintain homeostasis. However, cardiac disease states such as myocardial infarction, heart failure, and hypertension can induce the remodeling of cells involved in cardiac innervation, which is associated with an adverse clinical outcome. Although there are vast amounts of data for the histological structure and function of the cardiac autonomic nervous system, its molecular biological architecture in health and disease is still enigmatic in many aspects. Novel technologies such as single-cell RNA sequencing (scRNA-seq) hold promise for the genetic characterization of tissues at single-cell resolution. However, the relatively large size of neurons may impede the standardized use of these techniques. Here, this protocol exploits droplet-based single-nucleus RNA sequencing (snRNA-seq), a method to characterize the biological architecture of cardiac sympathetic neurons in health and disease. A stepwise approach is demonstrated to perform snRNA-seq of the bilateral superior cervical (SCG) and stellate ganglia (StG) dissected from adult mice. This method enables long-term sample preservation, maintaining an adequate RNA quality when samples from multiple individuals/experiments cannot be collected all at once within a short period of time. Barcoding the nuclei with hashtag oligos (HTOs) enables demultiplexing and the trace-back of distinct ganglionic samples post sequencing. Subsequent analyses revealed successful nuclei capture of neuronal, satellite glial, and endothelial cells of the sympathetic ganglia, as validated by snRNA-seq. In summary, this protocol provides a stepwise approach for snRNA-seq of sympathetic extrinsic cardiac ganglia, a method that has the potential for broader application in studies of the innervation of other organs and tissues.

Publication guidelines and recommendations for pupillary measurement in psychophysiological studies.

A variety of psychological and physical phenomena elicit variations in the diameter of pupil of the eye. Changes in pupil size are mediated by the relative activation of the sphincter pupillae muscle (decrease pupil diameter) and the dilator pupillae muscle (increase pupil diameter), innervated by the parasympathetic and sympathetic branches, respectively, of the autonomic nervous system. The current guidelines are intended to inform and guide psychophysiological research involving pupil measurement by (1) summarizing important aspects concerning the physiology of the pupil, (2) providing methodological and data-analytic guidelines and recommendations, and (3) briefly reviewing psychological phenomena that modulate pupillary reactivity. Because of the increased ease and tractability of pupil measurement, the goal of these guidelines is to promote accurate recording, analysis, and reporting of pupillary data in psychophysiological research.

The peculiarities of the heart rate regulation in boys and girls with different body composition, motor and eating behavior

BACKGROUND: There are a lot of works devoted to the study of the main regularities of the heart rate (HR) control in individuals depending on the body weight. Still, there are some uncleared and even controversial issues that significantly influence the notion of this process itself. Particularly, impaired HR variability in patients with the cardiometabolic syndrome is characterized by the weakening of the impact of both parasympathetic and sympathetic branches of the autonomic nervous system. The works devoted to the heart rate variability features in young people associated with the body weight are scarce.AIM: To study the peculiarities of the heart rate variability in boys and girls with different body composition, motor and eating behavior.MATERIALS AND METHODS: A cross-sectional, open, single-arm, non-randomized study of the HR variability in adolescents with different body fat mass (BFM) was carried out on the basis of the Center for Healthy Nutrition of Altai State University. The HR variability, nutritional status and physical activity index (PHAI) were studied in the groups of individuals with different body fat mass.RESULTS: We examined 168 people (85 boys and 83 girls). The surveyed belonged to the adolescent age period (boys from 17 to 21 years old, girls from 16 to 20 years old). The boys and girls examined by us had a different amount of BFM %. The HR variability, nutritional status and physical activity index were studied in 44 people with the low BFM, 71 people with the average BFM, 53 people with the increased BFM. In both sexes, the group with the increased BFM features an increase in the absolute (HF, ms2 ) and relative (HF%) oscillation power of the heart rate high-frequency component. The average value of the physical activity index in the group with the reduced BFM equals 1.52 ± 0.037 in boys, and 1.44 ± 0.099 in girls. The average value of the physical activity index in the group with the average BFM is 1.44 ± 0.029 and 1.42 ± 0.095 in boys and in girls respectively. The average value of the physical activity index in the group with the increased BFM is 1.23 (Q25–75 1.20–1.70) in boys, and 1.26 ± 0.33 in girls. The representatives of the group with the increased BFM have a higher caloric value (CV) of the daily intake. In young men, a higher CV was achieved due to increased consumption of fats and carbohydrates. In the girls of the third group, a higher CV of the daily intake was gained due to proteins, fats, carbohydrates.CONCLUSION: The results of the HR variability showed that the motor and eating behavior affect the state of the cardiac function in both boys and girls. An increase in the body fat mass in the individuals with a maximum CV of the daily intake and a minimum level of motor activity is associated with the prevalence of the parasympathetic branch of the autonomic nervous system in the heart rate control.

Schwann Cells in Digestive System Disorders.

Proper functioning of the digestive system is ensured by coordinated action of the central and peripheral nervous systems (PNS). Peripheral innervation of the digestive system can be viewed as intrinsic and extrinsic. The intrinsic portion is mainly composed of the neurons and glia of the enteric nervous system (ENS), while the extrinsic part is formed by sympathetic, parasympathetic, and sensory branches of the PNS. Glial cells are a crucial component of digestive tract innervation, and a great deal of research evidence highlights the important status of ENS glia in health and disease. In this review, we shift the focus a bit and discuss the functions of Schwann cells (SCs), the glial cells of the extrinsic innervation of the digestive system. For more context, we also provide information on the basic findings regarding the function of innervation in disorders of the digestive organs. We find diverse SC roles described particularly in the mouth, the pancreas, and the intestine. We note that most of the scientific evidence concerns the involvement of SCs in cancer progression and pain, but some research identifies stem cell functions and potential for regenerative medicine.

The Interplay between Autonomic Nervous System and Inflammation across Systemic Autoimmune Diseases.

The autonomic nervous system (ANS) and the immune system are deeply interrelated. The ANS regulates both innate and adaptive immunity through the sympathetic and parasympathetic branches, and an imbalance in this system can determine an altered inflammatory response as typically observed in chronic conditions such as systemic autoimmune diseases. Rheumatoid arthritis, systemic lupus erythematosus, and systemic sclerosis all show a dysfunction of the ANS that is mutually related to the increase in inflammation and cardiovascular risk. Moreover, an interaction between ANS and the gut microbiota has direct effects on inflammation homeostasis. Recently vagal stimulation techniques have emerged as an unprecedented possibility to reduce ANS dysfunction, especially in chronic diseases characterized by pain and a decreased quality of life as well as in chronic inflammation.

Effects of transcutaneous auricular vagus nerve stimulation on cardiovascular autonomic control in health and disease.

Autonomic nervous system (ANS) dysfunction is a well-known feature of cardiovascular diseases (CVDs). Studies on heart rate variability (HRV), a non-invasive method useful in investigating the status of cardiovascular autonomic control, have shown that a predominance of sympathetic modulation not only contributes to the progression of CVDs but has a pivotal role in their onset. Current therapies focus more on inhibition of sympathetic activity, but the presence of drug-resistant conditions and the invasiveness of some surgical procedures are an obstacle to complete therapeutic success. On the other hand, targeting the parasympathetic branch of the autonomic nervous system through invasive vagus nerve stimulation (VNS) has shown interesting results as alternative therapeutic approach for CVDs. However, the invasiveness and cost of the surgical procedure limit the clinical applicability of VNS and hinder the research on the physiological pathway involved. Transcutaneous stimulation of the auricular branch of the vagus nerve (tVNS) seems to represent an important non-invasive alternative with effects comparable to those of VNS with surgical implant. Thus, in the present narrative review, we illustrate the main studies on tVNS performed in healthy subjects and in three key examples of CVDs, namely heart failure, hypertension and atrial fibrillation, highlighting the neuromodulatory effects of this technique.

Role of the Autonomic Nervous System in Mechanism of Energy and Glucose Regulation Post Bariatric Surgery.

Even though lifestyle changes are the mainstay approach to address obesity, Sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) are the most effective and durable treatments facing this pandemic and its associated metabolic conditions. The traditional classifications of bariatric surgeries labeled them as “restrictive,” “malabsorptive,” or “mixed” types of procedures depending on the anatomical rearrangement of each one of them. This conventional categorization of bariatric surgeries assumed that the “restrictive” procedures induce their weight loss and metabolic effects by reducing gastric content and therefore having a smaller reservoir. Similarly, the “malabsorptive” procedures were thought to induce their main energy homeostatic effects from fecal calorie loss due to intestinal malabsorption. Observational data from human subjects and several studies from rodent models of bariatric surgery showed that neither of those concepts is completely true, at least in explaining the multiple metabolic changes and the alteration in energy balance that those two surgeries induce. Rather, neuro-hormonal mechanisms have been postulated to underly the physiologic effects of those two most performed bariatric procedures. In this review, we go over the role the autonomic nervous system plays- through its parasympathetic and sympathetic branches- in regulating weight balance and glucose homeostasis after SG and RYGB.

Stress, cognitive, emotional and ergonomic demands in interpreting and translation

Abstract The autonomic nervous system is responsible for modulating peripheral functions in the human body and consists of sympathetic and parasympathetic branches. Its activation affects, among other things, heart rate, respiratory rate, salivation, perspiration, pupillary dilation, and blink rate. For some years now, physiological measurements have found their way into interpreting and translation studies to investigate, in particular, cognitive, emotional and ergonomic demands and stress in translating, interpreting and post-editing. We conducted a meta-review of publications from 1990 until 2020 in order to investigate the relevance of (a) the four constructs of emotional, cognitive and ergonomic demands and physiological stress and of (b) physiological data for translation and interpreting research. With our selection of search terms, we identified 369 publications investigating one of the four constructs, of which 28 use physiological data. Analysis of the 28 studies shows a tendency towards triangulating physiological with other types of data, which reflects the complexity of the investigated tasks and constructs. Moreover, there seems to be an effort to increase sample size, which is an important step towards more robust results in quantitative research in the field.

Regulation of Blood Flow in the Cerebral Posterior Circulation by Parasympathetic Nerve Fibers: Physiological Background and Possible Clinical Implications in Patients With Vertebrobasilar Stroke.

Posterior circulation involves the vertebrobasilar arteries, which supply oxygen and glucose to vital human brainstem structures and other areas. This complex circulatory- perfusion system is not homogenous throughout the day; rather, its hemodynamic changes rely on physiological demands, ensuring brainstem perfusion. This dynamic autoregulatory pattern maintains cerebral perfusion during blood pressure changes. Accumulative evidence suggests that activity within the autonomic nervous system is involved in the regulation of cerebral blood flow. Neither the sympathetic nor parasympathetic nervous systems work independently. Functional studies have shown a tight and complicated cross talk between these systems. In pathological processes where sympathetic stimulation is present, systemic vasoconstriction is followed, representing the most important CNS parasympathetic trigger that will promote local vasodilation. Stroke is a clear example of this process. The posterior circulation is affected in 30% of strokes, causing high morbidity and mortality outcomes. Currently, the management of ischemic stroke is focused on thrombolytic treatment and endovascular thrombectomy within an overall tight 4.5 to 6 h ischemic time window. Therefore, the autonomic nervous system could represent a potential therapeutic target to modulate reperfusion after cerebral ischemia through vasodilation, which could potentially decrease infarct size and increase the thrombolytic therapeutic ischemic window. In addition, shifting the autonomic nervous system balance toward its parasympathetic branch has shown to enhance neurogenesis and decrease local inflammation. Regretfully, the vast majority of animal models and human research on neuromodulation during brain ischemia have been focused on anterior circulation with disappointing results. In addition, the source of parasympathetic inputs in the vertebrobasilar system in humans is poorly understood, substantiating a gap and controversy in this area. Here, we reviewed current available literature regarding the parasympathetic vascular function and challenges of its stimulation in the vertebrobasilar system.

Methylphenidate Improves Autonomic Functioning among Youth with Attention-Deficit/Hyperactivity Disorder.

Psychostimulants are commonly prescribed medications for youth with attention-deficit/hyperactivity disorder (ADHD). Limited studies have evaluated how psychostimulants (e.g., methylphenidate [MPH]) impact autonomic nervous system (ANS) indexes among youth with ADHD. Understanding the effects of MPH on autonomic functioning is essential, given that youth with ADHD have been shown to experience atypical autonomic functioning (i.e., reduced activity across both sympathetic and parasympathetic branches) compared to typically developing youth. The current study investigated how a specific psychostimulant, Osmotic Release Oral System [OROS] MPH, impacts parasympathetic (indexed by respiratory sinus arrhythmia [RSA]) and sympathetic (indexed by electrodermal activity [EDA]) functioning among youth with ADHD via a within-subjects, double-masked, cross-over design. Two hundred fifty-six participants (157 youth with ADHD), ages 5 to 13years, completed a two-minute resting baseline task while electrocardiograph and electrodermal data were obtained. Youth with ADHD completed the resting baseline task twice, 3weeks apart, once during active medication and once during placebo conditions (counterbalanced). Typically developing youth were assessed without medication or placebo. Youth with ADHD during the placebo condition exhibited reduced RSA and EDA compared to typically developing youth. In contrast, youth with ADHD during the medication condition did not differ significantly from typically developing youth with respect to either RSA nor EDA. As such, OROS MPH appears to normalize RSA and EDA levels among youth with ADHD to levels comparable to typically developing youth. Future studies including indexes of the ANS among youth with ADHD are urged to consider the impact of MPH.

The Bezold-Jarisch Reflex and The Inflammatory Response Modulation in Unanesthetized Endotoxemic Rats.

Evidence indicates that the activation of the parasympathetic branch of the autonomic nervous system may be effective in treating inflammatory diseases. Previously, we have described that baroreflex activation displays anti-inflammatory properties. Analogous to the baroreflex, the Bezold-Jarisch reflex also promotes parasympathetic activation with simultaneous inhibition of the sympathetic system. Thus, the present study aimed to evaluate whether the activation of the Bezold-Jarisch reflex would also have the ability to reduce inflammation in unanesthetized rats. We used lipopolysaccharide (LPS) injection (5mg/kg, i.p.) to induce systemic inflammation in male Wistar Hannover rats and phenylbiguanide (PBG) administration (5μg/kg, i.v.) to activate the Bezold-Jarisch reflex. Spleen, heart, hypothalamus, and blood samples were collected to determine the levels of cytokines. Compared to baseline, PBG reduced the arterial pressure (115±2 vs. 88±5mmHg) and heart rate (380±7 vs. 114±26bpm), immediately after its administration, confirming the activation of the parasympathetic system and inhibition of the sympathetic system. From the immunological point of view, the activation of the Bezold-Jarisch reflex decreased the plasma levels of TNF (LPS: 775±209 vs. PBG + LPS: 248±30pg/ml) and IL-6 levels in the spleen (LPS: 39±6 vs. PBG + LPS: 24±4pg/mg of tissue). However, it did not change the other cytokines in the plasma or the other tissues evaluated. These findings confirm that the activation of the Bezold-Jarisch reflex can modulate inflammation and support the understanding that the cardiovascular reflexes regulate the immune system.

Psychophysiological dynamics of emotional reactivity: Interindividual reactivity characterization and prediction by a machine learning approach

The fast reaction of the autonomic nervous system (ANS) to an emotional challenge (EC) is the result of a functional coupling between parasympathetic (PNS) and sympathetic (SNS) branches. This coupling can be characterized by measures of cross-correlations between electrodermal activity (EDA) (under the influence of the SNS) and the RR interval (the interval between R peaks) (under the influence of the PNS and the SNS). Significant interindividual variability has previously been reported in SNS-PNS coupling in emotional situations, and the present study aimed to identify interindividual cross-correlation variability in ANS reactivity. We therefore studied EDA and the RR interval in 62 healthy subjects, recorded during a 24-minute EC. A Gaussian Mixture Model was used to cluster tonic EDA-RR cross-correlations during the EC. This identified two clusters that were characterized by significant or non-significant cross-correlations (SCC and NCC clusters, respectively). The SCC cluster reported higher negative emotion after the EC, while the NCC cluster reported higher scores on the Center for Epidemiologic Studies–Depression scale. The latter finding suggests that NCC is a pathological mood pattern with altered negative perception. Furthermore, a machine learning model that included three parameters indexing the functionality of both branches of the ANS, measured at baseline, predicted cluster membership. Our results are a first step in detecting dysfunctional ANS reactivity in general population.

Analysis of heart rate variability in corn snakes (Pantherophis guttatus)

The assessment of heart rate variability (HRV) by linear methods in conjunction with Poincaré plots can be useful for evaluating cardiac regulation by the autonomic nervous system and for the diagnosis and prognosis of heart disease in snakes. In this report, we describe an analysis of HRV in conscious adult corn snakes Pantherophis guttatus (P. guttatus). The electrocardiogram (ECG) parameters were determined in adult corn snakes (8 females, 13 males) and used for HRV analysis, and the RR interval was analyzed by linear methods in the time and frequency domains. There was no sex-related difference in heart rate. However, significant differences were seen in the duration of the P, PR, and T waves and QRS complex; there was no difference in the QT interval. The values for the RR interval varied by 15.3% and 18.8% in male and female snakes, respectively, and there was considerable variation in the values for the high and low frequency domains. The changes in the time domain were attributed to regulation by the parasympathetic branch of the autonomic nervous system, in agreement with variations in the high and low frequency domains. The values for standard deviations 1 and 2 in Poincaré plots, as well as the values of the frequency domain, provide useful parameters for future studies of cardiac function in P. guttatus.

Neurohumoral Cardiac Regulation: Optogenetics Gets Into the Groove.

The cardiac autonomic nervous system (ANS) is the main modulator of heart function, adapting contraction force, and rate to the continuous variations of intrinsic and extrinsic environmental conditions. While the parasympathetic branch dominates during rest-and-digest sympathetic neuron (SN) activation ensures the rapid, efficient, and repeatable increase of heart performance, e.g., during the “fight-or-flight response.” Although the key role of the nervous system in cardiac homeostasis was evident to the eyes of physiologists and cardiologists, the degree of cardiac innervation, and the complexity of its circuits has remained underestimated for too long. In addition, the mechanisms allowing elevated efficiency and precision of neurogenic control of heart function have somehow lingered in the dark. This can be ascribed to the absence of methods adequate to study complex cardiac electric circuits in the unceasingly moving heart. An increasing number of studies adds to the scenario the evidence of an intracardiac neuron system, which, together with the autonomic components, define a little brain inside the heart, in fervent dialogue with the central nervous system (CNS). The advent of optogenetics, allowing control the activity of excitable cells with cell specificity, spatial selectivity, and temporal resolution, has allowed to shed light on basic neuro-cardiology. This review describes how optogenetics, which has extensively been used to interrogate the circuits of the CNS, has been applied to untangle the knots of heart innervation, unveiling the cellular mechanisms of neurogenic control of heart function, in physiology and pathology, as well as those participating to brain–heart communication, back and forth. We discuss existing literature, providing a comprehensive view of the advancement in the understanding of the mechanisms of neurogenic heart control. In addition, we weigh the limits and potential of optogenetics in basic and applied research in neuro-cardiology.

A method to quantify autonomic nervous system function in healthy, able-bodied individuals

BackgroundThe autonomic nervous system (ANS) maintains physiological homeostasis in various organ systems via parasympathetic and sympathetic branches. ANS function is altered in common diffuse and focal conditions and heralds the beginning of environmental and disease stresses. Reliable, sensitive, and quantitative biomarkers, first defined in healthy participants, could discriminate among clinically useful changes in ANS function. This framework combines controlled autonomic testing with feature extraction during physiological responses.MethodsTwenty-one individuals were assessed in two morning and two afternoon sessions over two weeks. Each session included five standard clinical tests probing autonomic function: squat test, cold pressor test, diving reflex test, deep breathing, and Valsalva maneuver. Noninvasive sensors captured continuous electrocardiography, blood pressure, breathing, electrodermal activity, and pupil diameter. Heart rate, heart rate variability, mean arterial pressure, electrodermal activity, and pupil diameter responses to the perturbations were extracted, and averages across participants were computed. A template matching algorithm calculated scaling and stretching features that optimally fit the average to an individual response. These features were grouped based on test and modality to derive sympathetic and parasympathetic indices for this healthy population.ResultsA significant positive correlation (p = 0.000377) was found between sympathetic amplitude response and body mass index. Additionally, longer duration and larger amplitude sympathetic and longer duration parasympathetic responses occurred in afternoon testing sessions; larger amplitude parasympathetic responses occurred in morning sessions.ConclusionsThese results demonstrate the robustness and sensitivity of an algorithmic approach to extract multimodal responses from standard tests. This novel method of quantifying ANS function can be used for early diagnosis, measurement of disease progression, or treatment evaluation.Trial registrationThis study registered with Clinicaltrials.gov, identifier NCT04100486. Registered September 24, 2019, https://www.clinicaltrials.gov/ct2/show/NCT04100486.

Location of Parasympathetic Innervation Regions From Electrograms to Guide Atrial Fibrillation Ablation Therapy: An in silico Modeling Study.

The autonomic nervous system (ANS) plays an essential role in the generation and maintenance of cardiac arrhythmias. The cardiac ANS can be divided into its extrinsic and intrinsic components, with the latter being organized in an epicardial neural network of interconnecting axons and clusters of autonomic ganglia called ganglionated plexi (GPs). GP ablation has been associated with a decreased risk of atrial fibrillation (AF) recurrence, but the accurate location of GPs is required for ablation to be effective. Although GP stimulation triggers both sympathetic and parasympathetic ANS branches, a predominance of parasympathetic activity has been shown. This study aims was to develop a method to locate atrial parasympathetic innervation sites based on measurements from a grid of electrograms (EGMs). Electrophysiological models representative of non-AF, paroxysmal AF (PxAF), and persistent AF (PsAF) tissues were developed. Parasympathetic effects were modeled by increasing the concentration of the neurotransmitter acetylcholine (ACh) in randomly distributed circles across the tissue. Different circle sizes of ACh and fibrosis geometries were considered, accounting for both uniform diffuse and non-uniform diffuse fibrosis. Computational simulations were performed, from which unipolar EGMs were computed in a 16 × 1 6 electrode mesh. Different distances of the electrodes to the tissue (0.5, 1, and 2 mm) and noise levels with signal-to-noise ratio (SNR) values of 0, 5, 10, 15, and 20 dB were tested. The amplitude of the atrial EGM repolarization wave was found to be representative of the presence or absence of ACh release sites, with larger positive amplitudes indicating that the electrode was placed over an ACh region. Statistical analysis was performed to identify the optimal thresholds for the identification of ACh sites. In all non-AF, PxAF, and PsAF tissues, the repolarization amplitude rendered successful identification. The algorithm performed better in the absence of fibrosis or when fibrosis was uniformly diffuse, with a mean accuracy of 0.94 in contrast with a mean accuracy of 0.89 for non-uniform diffuse fibrotic cases. The algorithm was robust against noise and worked for the tested ranges of electrode-to-tissue distance. In conclusion, the results from this study support the feasibility to locate atrial parasympathetic innervation sites from the amplitude of repolarization wave.

Cardiac autonomic functioning across stress and reward: Links with depression in emerging adults

The autonomic nervous system (ANS) has received much attention as a potential low-cost, peripheral indicator of depression. Despite theoretical support, however, results have been mixed as to whether indices of the ANS reliably index depression. In response, the present study sought to clarify the relation between ANS activity and depression by examining cardiac autonomic balance (CAB) and cardiac autonomic regulation (CAR), two composite indices of the parasympathetic and sympathetic nervous system, within both a stressful and rewarding context. We hypothesized that CABStress, representing the difference between the parasympathetic and sympathetic branches in response to stress, and CARReward, representing the summation of the two branches in response to reward, will be most indicative of depressogenic risk. We examined the parasympathetic (i.e., respiratory sinus arrhythmia) and sympathetic (i.e., pre-ejection period) responses of 97 emerging adults (Mage = 18.93) for a stress (i.e., negative mood induction) and reward (i.e., probabilistic learning) task, as well as their depressive symptoms at baseline, 3-week, and 6-week follow-up. Analyses found partial support for our hypotheses, revealing greater CARReward (i.e., coactivation of both branches) was related to lower depressive symptoms. Further, exploratory analyses examining gender differences found lower CABStress (i.e., sympathetically-oriented response) was predictive of an increasing trajectory of depression, but only among males. Overall, the current study highlights the importance of simultaneously examining both branches of the ANS across various environmental contexts. Research and clinical implications of the current findings are discussed.