Gregory Lewis

Three frequently used RSA metrics are investigated to document violations of assumptions for parametric analyses, moderation by respiration, influences of nonstationarity, and sensitivity to vagal blockade. Although all metrics are highly correlated, new findings illustrate that the metrics are noticeably different on the above dimensions. Only one method conforms to the assumptions for parametric analyses, is not moderated by respiration, is not influenced by nonstationarity, and reliably generates stronger effect sizes. Moreover, this method is also the most sensitive to vagal blockade. Specific features of this method may provide insights into improving the statistical characteristics of other commonly used RSA metrics. These data provide the evidence to question, based on statistical grounds, published reports using particular metrics of RSA.

In psychophysiological research, measurement of respiration has been dependent on transducers having direct contact with the participant. The current study provides empirical data demonstrating that a noncontact technology, infrared video thermography, can accurately estimate breathing rate and relative tidal volume across a range of breathing patterns. Video tracking algorithms were applied to frame‐by‐frame thermal images of the face to extract time series of nostril temperature and to generate breath‐by‐breath measures of respiration rate and relative tidal volume. The thermal indices of respiration were contrasted with criterion measures collected with inductance plethysmography. The strong correlations observed between the technologies demonstrate the potential use of facial video thermography as a noncontact technology to monitor respiration.

The current study evaluated processes underlying two common symptoms (i.e., state regulation problems and deficits in auditory processing) associated with a diagnosis of autism spectrum disorders. Although these symptoms have been treated in the literature as unrelated, when informed by the Polyvagal Theory, these symptoms may be viewed as the predictable consequences of depressed neural regulation of an integrated social engagement system, in which there is down regulation of neural influences to the heart (i.e., via the vagus) and to the middle ear muscles (i.e., via the facial and trigeminal cranial nerves). Respiratory sinus arrhythmia (RSA) and heart period were monitored to evaluate state regulation during a baseline and two auditory processing tasks (i.e., the SCAN tests for Filtered Words and Competing Words), which were used to evaluate auditory processing performance. Children with a …

This chapter applies hypotheses and principles derived from the polyvagal theory (Porges, 1995, 2001, 2007) to interpret mammalian vocalizations. The theory emphasizes the parallel phylogenetic shift in both the neural regulation of the autonomic nervous system and the evolutionary emergence of an integrated social engagement system that includes features optimizing conspecific mammalian vocal communication. The chapter presents the polyvagal hypothesis as a new way to interpret adaptive functions and acoustic features of mammalian vocalizations. The chapter emphasizes both the neural mechanisms involved in social communication, including the reciprocal relationship between production and reception of vocalizations, and the perceptual advantage that mammals have by vocalizing within a frequency band optimized by the physics of the middle ear.

Microelectrode arrays (MEAs) recording extracellular field potentials of human-induced pluripotent stem cell-derived cardiomyocytes (hiPS-CM) provide a rich data set for functional assessment of drug response. The aim of this work is the development of a method for a systematic analysis of arrhythmia using MEAs, with emphasis on the development of six parameters accounting for different types of cardiomyocyte signal irregularities. We describe a software approach to carry out such analysis automatically including generation of a heat map that enables quick visualization of arrhythmic liability of compounds. We also implemented signal processing techniques for reliable extraction of the repolarization peak for field potential duration (FPD) measurement even from recordings with low signal to noise ratios. We measured hiPS-CM's on a 48 well MEA system with 5 minute recordings at multiple time points (0.5, 1, 2 …

Decreased heart rate variability (HRV) is associated with posttraumatic stress disorder (PTSD) and depression symptoms, but PTSD's effects on the autonomic stress response and the potential influence of HRV biofeedback in stress relaxation training on improving PTSD symptoms are not well understood. The objective of this study was to examine the impact of a predeployment stress inoculation training (PRESTINT) protocol on physiologic measures of HRV in a large sample of the military population randomly assigned to experimental HRV biofeedback‐assisted relaxation training versus a control condition. PRESTINT altered the parasympathetic regulation of cardiac activity, with experimental subjects exhibiting greater HRV, that is, less arousal, during a posttraining combat simulation designed to heighten arousal. Autonomic reactivity was also found to be related to PTSD and self‐reported use of mental …

Caregiving by nonparents (alloparenting) and fathers is a defining aspect of human social behavior, yet this phenomenon is rare among mammals. Male prairie voles (Microtus ochrogaster) spontaneously exhibit high levels of alloparental care, even in the absence of reproductive experience. In previous studies, exposure to a pup was selectively associated with increased activity in oxytocin and vasopressin neurons along with decreased plasma corticosterone. In the present study, physiological, pharmacological and neuroanatomical methods were used to explore the autonomic and behavioral consequences of exposing male prairie voles to a pup. Reproductively naïve, adult male prairie voles were implanted with radiotransmitters used for recording ECG, temperature and activity. Males responded with a sustained increase in heart-rate during pup exposure. This prolonged increase in heart rate was not explained by novelty, locomotion or thermoregulation. Although heart rate was elevated during pup exposure, respiratory sinus arrhythmia (RSA) did not differ between these males and males exposed to control stimuli indicating that vagal inhibition of the heart was maintained. Blockade of beta-adrenergic receptors with atenolol abolished the pup-induced heart rate increase, implicating sympathetic activity in the pup-induced increase in heart rate. Blockade of vagal input to the heart delayed the males’ approach to the pup. Increased activity in brainstem autonomic regulatory nuclei was also observed in males exposed to pups. Together, these findings suggest that exposure to a pup activates both vagal and sympathetic systems. This unique …

StressEraser^® is a commercially marketed biofeedback device designed to enhance heart rate variability. StressEraser^® makes its internal calculations on beat-to-beat measures of finger pulse intervals. However, the accuracy and precision of StressEraser^® in quantifying interbeat intervals using finger pulse intervals has not been evaluated against standard laboratory equipment using R–R intervals. Accuracy was assessed by simultaneously recording interbeat intervals using StressEraser^® and a standard laboratory ECG system. The interbeat intervals were highly correlated between the systems. The average deviation in interbeat interval recordings between the systems was approximately 6 ms. Moreover, correlations approached unity between the systems on estimates of heart period, heart rate, and heart rate variability. Feedback from StressEraser^® is based on an interbeat time series that provides …

The evolution of the autonomic nervous system provides an organizing principle to interpret the adaptive significance of physiological systems in promoting social behavior and responding to social challenges. This phylogenetic shift in neural regulation of the autonomic nervous system in mammals has produced a neuroanatomically integrated social engagement system, including neural mechanisms that regulate both cardiac vagal tone and muscles involved in vocalization. Mammalian vocalizations are part of a conspecific social communication system, with several mammalian species modulating acoustic features of vocalizations to signal affective state. Prosody, defined by variations in rhythm and pitch, is a feature of mammalian vocalizations that communicate emotion and affective state. While the covariation between physiological state and the acoustic frequencies of vocalizations is neurophysiologically …

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 (0.25 mg/kg) or OXT antagonist (OXT-A, 20 mg/kg), and were allowed to recover with or without their sibling …

Auditory hypersensitivities are a common feature of autism spectrum disorder (ASD). In the present study the effectiveness of a novel intervention, the Listening Project Protocol (LPP) was evaluated in two trials conducted with children diagnosed with ASD. LPP was developed to reduce auditory hypersensitivities. LPP is based on a theoretical “neural exercise” model that uses computer altered acoustic stimulation to recruit the neural regulation of middle ear muscles. Features of the intervention stimuli were informed by basic research in speech and hearing sciences that has identified the specific acoustic frequencies necessary to understand speech, which must pass through middle ear structures before being processed by other components of the auditory system. LPP was hypothesized to reduce auditory hypersensitivities by increasing the neural tone to the middle ear muscles to functionally dampen competing sounds in frequencies lower than human speech. The trials demonstrated that LPP, when contrasted to control conditions, selectively reduced auditory hypersensitivities. These findings are consistent with the Polyvagal Theory, which emphasizes the role of the middle ear muscles in social communication.

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-min seated baseline phase at the beginning of the experimental session. Participants then completed a computerized startle task in which predictable and unpredictable shocks …

Heart rate variability (HRV) is highly nonstationary, even if no perturbing influences can be identified during the recording of the data. The nonstationarity becomes more profound when HRV data are measured in intrinsically nonstationary environments, such as social stress. In general, HRV data measured in such situations are more difficult to analyze than those measured in constant environments. In this paper, we analyze HRV data measured during a social stress test using two multiscale approaches, the adaptive fractal analysis (AFA) and scale-dependent Lyapunov exponent (SDLE), for the purpose of uncovering differences in HRV between chronic fatigue syndrome (CFS) patients and their matched-controls. CFS is a debilitating, heterogeneous illness with no known biomarker. HRV has shown some promise recently as a non-invasive measure of subtle physiological disturbances and trauma that are otherwise difficult to assess. If the HRV in persons with CFS are significantly different from their healthy controls, then certain cardiac irregularities may constitute good candidate biomarkers for CFS. Our multiscale analyses show that there are notable differences in HRV between CFS and their matched controls before a social stress test, but these differences seem to diminish during the test. These analyses illustrate that the two employed multiscale approaches could be useful for the analysis of HRV measured in various environments, both stationary and nonstationary.

The objective of this pilot study was to design, develop, and evaluate a predeployment stress inoculation training (PRESIT) preventive intervention to enable deploying personnel to cope better with combat-related stressors and mitigate the negative effects of trauma exposure. The PRESIT program consisted of three predeployment training modules: (1) educational materials on combat and operational stress control, (2) coping skills training involving focused and relaxation breathing exercises with biofeedback, and (3) exposure to a video multimedia stressor environment to practice knowledge and skills learned in the first two modules. Heart rate variability assessed the degree to which a subset of participants learned the coping skills. With a cluster randomized design, data from 351 Marines randomized into PRESIT and control groups were collected at predeployment and from 259 of these who responded to …

Background:While efficacy of Sudarshan Kriya Yoga (SKY) has been demonstrated in a number of prior studies, little is known about the effects of SKY taught as part of the Your Enlightened Side (YES+) workshop designed for college students and other young adults.Aims:This study aimed to assess the effects of YES+, a yogic breathing-based life skills workshop, on multiple measures of well-being and physiological stress response.Materials and Methods:Two nonrandomized open-trial pilot studies were conducted with a total of 74 young adults (age 25.4±6.6 years; 55% female). Study 1 collected a variety of self-report questionnaires at baseline, postworkshop, and 1-month follow-up. Study 2 collected self-report questionnaires in addition to electrocardiography with a stationary cycling challenge at baseline and 1-month follow-up.Results:Study 1: Improvements in self-reported depression (P's≤ 0.010 …