Cardiac Vagal Regulation Is Impeded in Children With Cyclic Vomiting Syndrome.

INTRODUCTION: The pathophysiology underlying cyclic vomiting syndrome (CVS) remains undefined. Scant data and distinct clinical features point to altered autonomic nervous system function. Autonomic signaling can be noninvasively assessed through cardiac indices of parasympathetic vagal regulation, which is reduced in children with disorders of gut-brain interaction. We aimed to examine dynamic cardiac vagal regulation in children with CVS compared with that in healthy controls (HC). METHODS: A total of 31 children with CVS evaluated in a tertiary care CVS center and 66 HC (ages 8-18 years) underwent cardiac autonomic function assessment. Electrocardiogram recordings were conducted during 3-minute sit/stand/sit posture challenges. The electrocardiogram-derived variables heart period, respiratory sinus arrhythmia (RSA), and vagal efficiency (VE) were analyzed using linear regression and mixed-effects modeling. RESULTS: After exclusion of medication confounders, 23 patients with CVS were included in analyses. Both groups were comparable in age, gender, and body mass index. Compared with HC, children with CVS had shorter heart period (standardized mean difference range: 1.15-1.22, all P values < 0.05) and lower RSA (SMD range: 0.66-0.88, all P values < 0.05). Patients with CVS had significantly lower VE during the entire course of posture shifts, compared with HC ( B = -19.87, SE = 6.95, t = -2.86, P = 0.005, SMD = 0.76). DISCUSSION: Children with CVS have suboptimal parasympathetic autonomic regulation compared with HC, indexed by reduced RSA and VE, even during their interepisodic well phase. Abnormal vagal modulation may underlie CVS pathophysiology, comorbidities, and triggers. Assessing VE during posture stressors could inform therapeutic interventions.

Association of Self-Reported Autonomic Symptoms With Sensor-Based Physiological Measures.

OBJECTIVE: Autonomic regulation of organ and tissues may give rise to disruptions of typical functions. The Body Perception Questionnaire Short Form (BPQ-SF) includes items that were developed to assess autonomic symptoms in daily life. This pair of studies aimed to establish previously unexplored psychometric properties of the BPQ-SF autonomic symptoms scale, develop normative values for clinical and research use, and assess the convergence of self-reports with sensor-based measures. METHODS: Study 1 reports exploratory and confirmatory factor analysis on BPQ-SF autonomic symptom items from a large US population-based online study ( n = 2048). In study 2, BPQ-SF scores were examined for associations with heart period, respiratory sinus arrhythmia, and skin conductance during seated leg lifts in a community sample ( n = 62). RESULTS: Study 1 results supported a two-factor supradiaphragmatic and subdiaphragmatic autonomic symptom solution (confirmatory factor analysis: root mean squared error of approximation = 0.040, Comparative Fit Index = 0.99, Tucker-Lewis Index = 0.99), although a one-factor solution also fit the data well (root mean squared error of approximation = 0.080, Comparative Fit Index = 0.99, Tucker-Lewis Index = 0.99). In study 2, heart period responses to leg lifts and rests were demonstrated at all autonomic symptom levels. However, low autonomic symptoms were associated with optimal autonomic nervous system patterns of activation and recovery to baseline levels. Moderate symptoms were associated with prolonged sympathetic activation. The highest symptom levels were associated with impaired autonomic nervous system coordination across activation and recovery. CONCLUSIONS: Results support the utility of self-reports of autonomic symptoms in research and clinical applications, with higher symptoms likely indicating autonomic impairment.

Differential Momentary Reports of Stress and Affect Associated With Alcohol Consumption in Middle-Aged Versus Younger Adults.

Background: Stress is a motivator to consume alcohol, a well-documented relapse risk, and is known to differentially affect biological and psychological processes as people age.Objectives: Because alcohol consumption is known to acutely decrease stress and increase affect, this study examined differences in ratings of stress and affect in middle-aged versus younger adults who regularly consume alcohol.Methods: A sample of younger (n = 17) and middle-aged (n = 18) drinkers was studied during a 3-day period of typical alcohol consumption. Resting levels of respiratory sinus arrhythmia (RSA) were measured during a baseline study visit since RSA is a well-documented biomarker of stress and is known to decrease with age. Ecological momentary assessment (EMA) survey ratings (n = 1,598) were modeled using hierarchical regression to assess differences in stress and affect throughout the day between the two age groups.Results: As anticipated, middle-aged participants had lower RSA than those who were younger. Although the middle-aged adults showed overall lower stress, generally they also experienced higher affect than the younger adults. Middle-aged adults experienced a significant reduction in stress following drinking while no such effect was observed in the younger adults.Conclusions: To our knowledge, this is the first investigation using EMA methodology to examine stress and affect between younger and middle-aged adults who habitually consume alcohol. These cross-sectional data suggest potential momentary stress relief to engaging with moderate alcohol consumption in a middle-aged population. Future work must address this important motivational process in curtailing maintenance of alcohol consumption and preventing escalation of consumption.

Is Oxytocin "Nature's Medicine"?

Oxytocin is a pleiotropic, peptide hormone with broad implications for general health, adaptation, development, reproduction, and social behavior. Endogenous oxytocin and stimulation of the oxytocin receptor support patterns of growth, resilience, and healing. Oxytocin can function as a stress-coping molecule, an anti-inflammatory, and an antioxidant, with protective effects especially in the face of adversity or trauma. Oxytocin influences the autonomic nervous system and the immune system. These properties of oxytocin may help explain the benefits of positive social experiences and have drawn attention to this molecule as a possible therapeutic in a host of disorders. However, as detailed here, the unique chemical properties of oxytocin, including active disulfide bonds, and its capacity to shift chemical forms and bind to other molecules make this molecule difficult to work with and to measure. The effects of oxytocin also are context-dependent, sexually dimorphic, and altered by experience. In part, this is because many of the actions of oxytocin rely on its capacity to interact with the more ancient peptide molecule, vasopressin, and the vasopressin receptors. In addition, oxytocin receptor(s) are epigenetically tuned by experience, especially in early life. Stimulation of G-protein-coupled receptors triggers subcellular cascades allowing these neuropeptides to have multiple functions. The adaptive properties of oxytocin make this ancient molecule of special importance to human evolution as well as modern medicine and health; these same characteristics also present challenges to the use of oxytocin-like molecules as drugs that are only now being recognized. SIGNIFICANCE STATEMENT: Oxytocin is an ancient molecule with a major role in mammalian behavior and health. Although oxytocin has the capacity to act as a "natural medicine" protecting against stress and illness, the unique characteristics of the oxytocin molecule and its receptors and its relationship to a related hormone, vasopressin, have created challenges for its use as a therapeutic drug.

Associations between acoustic features of maternal speech and infants' emotion regulation following a social stressor.

Caregiver voices may provide cues to mobilize or calm infants. This study examined whether maternal prosody predicted changes in infants' biobehavioral state after the still face, a stressor in which the mother withdraws and reinstates social engagement. Ninety-four dyads participated in the study (infant age 4-8 months). Infants' heart rate and respiratory sinus arrhythmia (measuring cardiac vagal tone) were derived from an electrocardiogram (ECG). Infants' behavioral distress was measured by negative vocalizations, facial expressions, and gaze aversion. Mothers' vocalizations were measured via a composite of spectral analysis and spectro-temporal modulation using a two-dimensional fast Fourier transformation of the audio spectrogram. High values on the maternal prosody composite were associated with decreases in infants' heart rate (ß = -.26, 95% CI: [-0.46, -0.05]) and behavioral distress (ß = -.23, 95% CI: [-0.42, -0.03]), and increases in cardiac vagal tone in infants whose vagal tone was low during the stressor (1 SD below mean ß = .39, 95% CI: [0.06, 0.73]). High infant heart rate predicted increases in the maternal prosody composite (ß = .18, 95% CI: [0.03, 0.33]). These results suggest specific vocal acoustic features of speech that are relevant for regulating infants' biobehavioral state and demonstrate mother-infant bi-directional dynamics.

Heart Rate Variability: A Personal Journey.

Heart rate variabfility (HRV) has been a focal point throughout my academic history. To put into perspective, I have published studies spanning seven decades focusing on HRV (1969-2022). My interest in HRV started early in graduate school and continues to be an important portal informing my theoretical perspective. The current paper tracks some of this history, which started as an empirical observation and moved through several scientific stages including development of quantitative methods and investigations of neural mechanisms. Along this journey a variety of hypotheses were tested including the relative sensitivity of HRV metrics to neural mechanisms, psychological processes, and medical diagnoses. In addition, the research led to the identification of portal of intervention that have become strategies to optimize mental and physical health. These apparent disparate programs of inquiry have been tightly merged as the Polyvagal Theory evolved. In the sections below, I have shared my personal journey through these stages of scientific inquiry and my attempts to integrate the new knowledge in an expansive theoretical model.

Infants' stress responses and protest behaviors at childcare entry and the role of care providers.

During the transition from home to childcare, 70 15-month-old infants were videotaped, and their negative emotions were rated. Infants' attachments to mothers were assessed prior to child care entry and to care providers five months later using the Strange Situation Procedure (SSP). Infant heart rate was monitored at home, during adaptation to childcare (mothers present), and during subsequent separations. Respiratory sinus arrhythmia (RSA) was computed from the beat-to-beat measures of heart rate to reflect vagal tone, which is reduced during chronic states of stress, and was collected upon Arrival, during in-group Play, and when in the Group more generally. All infants responded to childcare entry with low RSA levels indicating stress. However, during adaptation with the mother present, RSA was higher for securely attached infants. On the first separation day, 35.3% of the infants fussed and cried extensively. These intense protests predicted later secure attachments to care providers, which adaptively helped to reduce stress, especially in infants who protested extensively, as if summoning their mothers back. Because extensive protest suggests limited regulatory capacities, infants risk overburdening the stress system when left unsupported.

Impaired Vagal Efficiency Predicts Auricular Neurostimulation Response in Adolescent Functional Abdominal Pain Disorders.

INTRODUCTION: To determine whether pretreatment vagal efficiency (VE), respiratory sinus arrhythmia, and heart period can predict pain improvement with auricular neurostimulation in pediatric functional abdominal pain disorders. METHODS: A total of 92 adolescents with functional abdominal pain disorders underwent a 4-week randomized, double-blinded, sham-controlled auricular neurostimulation trial. Electrocardiogram-derived variables at baseline were used to predict pain using mixed effects modeling. RESULTS: A 3-way interaction (95% confidence intervals: 0.004-0.494) showed that the treatment group subjects with low baseline VE had lower pain scores at week 3. There was no substantial change in the placebo or high VE treatment group subjects. This effect was supported by a significant correlation between baseline VE and degree of pain reduction only in the treatment group. DISCUSSION: Impaired cardiac vagal regulation measured by VE predicts pain improvement with auricular neurostimulation.

Traumatic stress and the autonomic brain-gut connection in development: Polyvagal Theory as an integrative framework for psychosocial and gastrointestinal pathology.

A range of psychiatric disorders such as anxiety, depression, and post-traumatic stress disorder frequently co-occur with functional gastrointestinal (GI) disorders. Risk of these pathologies is particularly high in those with a history of trauma, abuse, and chronic stress. These scientific findings and rising awareness within the healthcare profession give rise to a need for an integrative framework to understand the developmental mechanisms that give rise to these observations. In this paper, we introduce a plausible explanatory framework, based on the Polyvagal Theory (Porges, Psychophysiology, 32, 301-318, 1995; Porges, International Journal of Psychophysiology, 42, 123-146, 2001; Porges, Biological Psychology, 74, 116-143, 2007), which describes how evolution impacted the structure and function of the autonomic nervous system (ANS). The Polyvagal Theory provides organizing principles for understanding the development of adaptive diversity in homeostatic, threat-response, and psychosocial functions that contribute to pathology. Using these principles, we outline possible mechanisms that promote and maintain socioemotional and GI dysfunction and review their implications for therapeutic targets.

Autonomic regulation of preterm infants is enhanced by Family Nurture Intervention.

Preterm infants have maturational delays in several neurobehavioral systems. This study assesses the impact of the Family Nurture Intervention (FNI) in the neonatal intensive care unit (NICU) on the maturation of autonomic regulation of preterm infants. Preterm infants born at 26-34 weeks postmenstrual age (PMA) were assigned to groups receiving either standard care (SC) or SC plus FNI, using a randomized controlled trial design. At two collection time points, approximately 35 weeks and 41 weeks PMA, electrocardiograms (ECG) were monitored for approximately 1 hour during sleep. Heart rate and respiratory sinus arrhythmia (RSA) were quantified from the ECG. Across the two time points, the FNI group exhibited greater increases in RSA (Cohen's d = 0.35) and slope between RSA and heart rate, as a measure of vagal efficiency (Cohen's d = 0.62). These results document that FNI resulted in enhanced autonomic regulation consistent with greater maturation of cardiac function. These and previous findings strongly suggest that facilitating early nurturing interactions and emotional connection between preterm infants and their mothers is a practicable and effective means of optimizing postnatal development in preterm infants. Interpretation of these autonomic function results also enriches our understanding of the potential long-term beneficial outcomes of FNI by drawing upon polyvagal theory, which explains how autonomic state provides a neurophysiological platform for optimal co-regulation between infant and caregiver, and by drawing upon calming cycle theory, which provides a model for understanding how repeated mother/infant calming interactions positively condition autonomic state and reinforce approach, prosocial behaviors.

Oxytocin promotes functional coupling between paraventricular nucleus and both sympathetic and parasympathetic cardioregulatory nuclei.

The neuropeptide oxytocin (OXT) facilitates prosocial behavior and selective sociality. In the context of stress, OXT also can down-regulate hypothalamic-pituitary-adrenal (HPA) axis activity, leading to consideration of OXT as a potential treatment for many socioaffective disorders. However, the mechanisms through which administration of exogenous OXT modulates social behavior in stressful environmental contexts are not fully understood. Here, we investigate the hypothesis that autonomic pathways are components of the mechanisms through which OXT aids the recruitment of social resources in stressful contexts that may elicit mobilized behavioral responses. Female prairie voles (Microtus ochrogaster) underwent a stressor (walking in shallow water) following pretreatment with intraperitoneal OXT (0.25mg/kg) or OXT antagonist (OXT-A, 20mg/kg), and were allowed to recover with or without their sibling cagemate. Administration of OXT resulted in elevated OXT concentrations in plasma, but did not dampen the HPA axis response to a stressor. However, OXT, but not OXT-A, pretreatment prevented the functional coupling, usually seen in the absence of OXT, between paraventricular nucleus (PVN) activity as measured by c-Fos immunoreactivity and HPA output (i.e. corticosterone release). Furthermore, OXT pretreatment resulted in functional coupling between PVN activity and brain regions regulating both sympathetic (i.e. rostral ventrolateral medulla) and parasympathetic (i.e. dorsal vagal complex and nucleus ambiguous) branches of the autonomic nervous system. These findings suggest that OXT increases central neural control of autonomic activity, rather than strictly dampening HPA axis activity, and provides a potential mechanism through which OXT may facilitate adaptive and context-dependent behavioral and physiological responses to stressors.

Corrigendum to' The vagal paradox: A polyvagal solution' [Compr. Psychoneuroendocrinology 16C (2023) 100200].

[This corrects the article DOI: 10.1016/j.cpnec.2023.100200.].

Relation between Respiratory Sinus Arrythymia and Startle Response during Predictable and Unpredictable Threat.

Research suggests that lower respiratory sinus arrhythmia (RSA) is associated with greater aversive responding. One physiological indicator of aversive responding is startle potentiation. While a few studies have demonstrated an inverse association between RSA and startle potentiation, no study to date has distinguished whether this relation is similar for predictable versus unpredictable aversive stimuli. This is an important distinction, given that degree of predictability has been shown to be an important determinant of aversive responding. The present study examined whether resting RSA was associated with startle eye blink responding during predictable and unpredictable threat of electric shock. Resting RSA was collected during a 6-minute seated baseline phase at the beginning of the experimental session. Participants then completed a computerized startle task in which predictable and unpredictable shocks were administered. Results indicated that lower resting RSA was associated with greater startle potentiation during unpredictable threat, but not during predictable threat. These findings are consistent with a growing body of literature suggesting that individual differences in RSA are associated with aversive responding, and extend previous work by suggesting that RSA may be more robustly associated with a heightened sensitivity to unpredictable threat. This pattern of results may have implications for the understanding of pathological anxiety given that individuals with anxiety disorders typically exhibit low RSA and heightened responding during unpredictable threat.

Respiratory sinus arrhythmia: a marker for positive social functioning and receptive language skills in children with autism spectrum disorders.

The current study builds on the emerging autism spectrum disorder (ASD) literature that associates autonomic nervous system activity with social function, and examines the link between respiratory sinus arrhythmia (RSA) and both social behavior and cognitive function. The RSA response pattern was assessed in 23 4- to 7-year-old children diagnosed with an ASD. Higher baseline RSA amplitudes were associated with better social behavior (i.e., more conventional gestures, more instances of joint attention) and receptive language abilities. Similar to reports of typically developing children, ASD children with higher RSA amplitude at baseline showed greater RSA and HP reactivity during an attention-demanding task. These results highlight the importance of studying RSA as a marker of positive function in children with ASD.

The vagal paradox: A polyvagal solution.

Although there is a consistent literature documenting that vagal cardioinhibitory pathways support homeostatic functions, another less frequently cited literature implicates vagal cardioinhibitory pathways in compromises to survival in humans and other mammals. The latter is usually associated with threat reactions, chronic stress, and potentially lethal clinical conditions such as hypoxia. Solving this 'vagal paradox' in studies conducted in the neonatal intensive care unit served as the motivator for the Polyvagal Theory (PVT). The paradox is resolved when the different functions of vagal cardioinhibitory fibers originating in two anatomically distinguishable brainstem areas are recognized. One pathway originates in a dorsal area known as the dorsal motor nucleus of the vagus and the other in a ventral area of the brainstem known as nucleus ambiguus. Unlike mammals, in all ancestral vertebrates from which mammals evolved, cardioinhibitory vagal fibers primarily originate in the dorsal motor nucleus of the vagus. Thus, in mammals the vagus nerve is 'poly' vagal because it contains two distinct efferent pathways. Developmental and evolutionary biology identify a ventral migration of vagal cardioinhibitory fibers that culminate in an integrated circuit that has been labeled the ventral vagal complex. This complex consists of the interneuronal communication of the ventral vagus with the source nuclei involved in regulating the striated muscles of the head and face via special visceral efferent pathways. This integrated system enables the coordination of vagal regulation of the heart with sucking, swallowing, breathing, and vocalizing and forms the basis of a social engagement system that allows sociality to be a potent neuromodulator resulting in calm states that promote homeostatic function. These biobehavioral features, dependent on the maturation of the ventral vagal complex, can be compromised in preterm infants. Developmental biology informs us that in the immature mammal (e.g., fetus, preterm infant) the ventral vagus is not fully functional and myelinization is not complete; this neuroanatomical profile may potentiate the impact of vagal cardioinhibitory pathways originating in the dorsal motor nucleus of the vagus. This vulnerability is confirmed clinically in the life-threatening reactions of apnea and bradycardia in human preterm newborns, which are hypothetically mediated through chronotropic dorsal vagal pathways. Neuroanatomical research documents that the distribution of cardioinhibitory neurons representing these two distinct vagal source nuclei varies among mammals and changes during early development. By explaining the solution of the 'vagal paradox' in the preterm human, the paper highlights the functional cardioinhibitory functions of the two vagal source nuclei and provides the scientific foundation for the testing of hypotheses generated by PVT.

A study of respiratory sinus arrhythmia and stuttering persistence.

INTRODUCTION: The present study investigated potential differences in respiratory sinus arrhythmia between preschool-age children with persisting stuttering, children who recovered from stuttering, and children who do not stutter. METHODS: Participants were 10 children with persisting stuttering (persisting group), 20 children who recovered from stuttering (recovered group), and 36 children who do not stutter (non-stuttering group). Participants viewed a neutral video clip to establish a pre-arousal baseline and then viewed two emotionally-arousing video clips (positive and negative, counterbalanced). Age-appropriate speaking tasks followed each of the video clips (post-baseline, post-positive, and post-negative). Respiratory sinus arrhythmia (RSA), an index of parasympathetic nervous system activity, was measured during the video clips and subsequent speaking tasks. RESULTS: First, the persisting group, recovered group, and non-stuttering group did not significantly differ in baseline RSA. Second, during the emotionally-arousing video clips, there was a significant group x condition interaction, with the recovered group exhibiting significantly lower RSA in the positive than negative condition, and the non-stuttering group exhibiting significantly higher RSA in the positive than negative condition. Third, in the narrative tasks, there was a significant group x condition interaction, with a greater difference in RSA between the post-baseline speaking task and the post-positive and post-negative speaking tasks for the persisting compared to the non-stuttering group. Lastly, a follow-up analysis indicated that the recovered and nonstuttering groups, compared to the persisting group, exhibited significantly greater RSA during the baseline (neutral) condition compared to the post-neutral narrative task. CONCLUSIONS: Findings provide a physiological perspective of emotion within children who stutter and persist and children who stutter and recover. Future investigations with larger sample sizes and diverse methodologies are necessary to provide novel insights on the specific emotion-related processes that are potentially involved with persistence of stuttering in young children.

Appeasement: replacing Stockholm syndrome as a definition of a survival strategy.

Background: Stockholm syndrome or traumatic bonding (Painter & Dutton, Patterns of emotional bonding in battered women: Traumatic bonding. International Journal of Women's Studies, 8(4), 363-375, 1985) has been used in mainstream culture, legal, and some clinical settings to describe a hypothetical phenomenon of trauma survivors developing powerful emotional attachments to their abuser. It has frequently been used to explain the reported 'positive bond' between some kidnap victims and their captor's, although scarce empirical research has supported this assertion. It has been used in various situations where interpersonal violence and mind control are reported and where clear power differentials exist, such as in child sexual abuse, intimate partner violence, human trafficking, and hostage situation scenarios.Objective: We propose replacing Stockholm syndrome with 'appeasement,' a term that can be explained through a biopsychological model (i.e. Polyvagal Theory) to describe how survivors may appear emotionally connected with their perpetrators to effectively adapt to life-threatening situations by calming the perpetrator.Conclusion: We believe the term appeasement will demystify the reported survivor experiences and will, in the eyes of the public, victims, and survivors, provide a science-based explanation for their narratives of survival that may initially appear to be contradictory. By understanding the potent reflexive neurobiological survival mechanisms embedded in appeasement, individuals and families can operationalise their survival from a perspective that supports resilience, a healthy long-term recovery, and normalises their coping responses as survival techniques.

Changing and redefining how victims are viewed and portrayed in mainstream media.Appeasement emphasises the asymmetry and adaptive strategy used to regulate and calm the captor, thus minimising potential injury and abuse.Stockholm syndrome does not reflect the survivor's experience nor does it acknowledge the negative impact that the label has on the survivor.

Association of childhood maltreatment with adult body awareness and autonomic reactivity: The moderating effect of practicing body psychotherapy.

Research shows the disruptive effects of early maltreatment on the autonomic nervous system (ANS) functioning in adulthood. Psychotherapists not only tend to report higher rates of personal experience with early maltreatment, but also fewer mental problems and disturbances in adulthood, as compared to other professions. However, the role of the ANS in these processes has been understudied despite the relevance of the therapist's psychological state and related nonverbal communication for the therapeutic alliance. By comparing body psychotherapists to the general population, the present study aimed to explore the effects of practicing body psychotherapy (BPT) on the link between early maltreatment and autonomic reactivity in adulthood. An online study included 570 body psychotherapists from 35 countries (54% from the United States, Mage = 52.92, 81% of females) and 592 participants from the U.S. general population (Mage = 51.89, 78% females). We first inspected the factorial structure of the Body Perception Questionnaire-Short Form (Cabrera et al., 2018) in the specific population of BPT practitioners, confirming the three-factor model with one body awareness and two autonomic reactivity factors. Compared to the general population, BPT practitioners reported higher levels of childhood maltreatment, but fewer autonomic symptoms in adulthood, better differentiation of body awareness and autonomic reactivity, and a weaker association between childhood maltreatment experiences and present-day autonomic symptoms. Results are discussed in the framework of polyvagal theory (Porges, 1995, 2011). (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Peripheral oxytocin administration buffers autonomic but not behavioral responses to environmental stressors in isolated prairie voles.

Negative social experiences such as social stressors and isolation influence mental and physical illnesses, including affective disorders and heart disease. Studies focused on socially monogamous prairie voles can provide insight into neurobiological systems that underlie the consequences of negative social interactions. Female prairie voles were exposed to 28 days of social isolation or pairing with a female sibling (control). Voles were administered daily oxytocin [20 µg/50 µl, subcutaneous (sc)] or saline vehicle (50 µl, sc) for 14 days and exposed to two behavioral stressors [elevated plus maze (EPM) and resident-intruder test]. Brain tissue was collected for analysis of central peptide levels in the hypothalamic paraventricular nucleus (PVN). Isolation produced autonomic changes [increased heart rate (HR) and decreased HR variability) during both acute stressors and increased anxiety behaviors in the EPM. Oxytocin injection prevented the autonomic consequences of the acute stressors in isolated prairie voles, but did not affect the behaviors tested under the present conditions. Oxytocin had no effect on the behavioral or autonomic responsiveness in paired prairie voles. Oxytocin injection may exert a beneficial effect on autonomic responses to stressors in isolated animals through increasing the number of oxytocin-containing neurons and decreasing the number of corticotropin-releasing hormone-containing neurons in the PVN. Oxytocinergic mechanisms may serve to compensate for autonomic responses associated with chronic isolation and exposure to both social and non-social acute stressors.

Sluggish vagal brake reactivity to physical exercise challenge in children with selective mutism.

Cardiovascular response patterns to laboratory-based social and physical exercise challenges were evaluated in 69 children and adolescents, 20 with selective mutism (SM), to identify possible neurophysiological mechanisms that may mediate the behavioral features of SM. Results suggest that SM is associated with a dampened response of the vagal brake to physical exercise that is manifested as reduced reactivity in heart rate and respiration. Polyvagal theory proposes that the regulation of the vagal brake is a neurophysiological component of an integrated social engagement system that includes the neural regulation of the laryngeal and pharyngeal muscles. Within this theoretical framework, sluggish vagal brake reactivity may parallel an inability to recruit efficiently the structures involved in speech. Thus, the findings suggest that dampened autonomic reactivity during mobilization behaviors may be a biomarker of SM that can be assessed independent of the social stimuli that elicit mutism.