When humor is a matter of heart: Effects on emotional state and interbeat interval.

Previous studies demonstrated that exposure to humor has beneficial effects on psychological well-being. In the present work, we investigated the behavioral and psychophysiological effects of different types of humor on psychological well-being and on the performance during the execution of a stressful cognitive task. To this aim, we examined the behavioral and psychophysiological effects of ToM humorous and Slapstick humorous comic strips before and after executing a stressful cognitive task. We hypothesized that only slapstick humor could reduce the level of anxiety, increase positive affect and improve performance on the cognitive task. Our findings revealed that, at a specific point in time, exposure to ToM Humor and No Humor strips were associated with lower IBI (higher HR, increase in cardiac recruitment) than slapstick humor. This result suggests that humor involving ToM abilities and No Humor strips elicited a greater cognitive engagement level than slapstick humor. Moreover, in an exploratory analysis we found a positive correlation between cardiac deactivation during the exposure to slapstick Humor and individual empathy scores, suggesting that the empathy skills might influence cardiac recruitment and the level of cognitive engagement during the exposure to humorous material.

Interbeat interval-based sleep staging: work in progress toward real-time implementation.

Objective. Cardiac activity changes during sleep enable real-time sleep staging. We developed a deep neural network (DNN) to detect sleep stages using interbeat intervals (IBIs) extracted from electrocardiogram signals.Approach. Data from healthy and apnea subjects were used for training and validation; 2 additional datasets (healthy and sleep disorders subjects) were used for testing. R-peak detection was used to determine IBIs before resampling at 2 Hz; the resulting signal was segmented into 150 s windows (30 s shift). DNN output approximated the probabilities of a window belonging to light, deep, REM, or wake stages. Cohen's Kappa, accuracy, and sensitivity/specificity per stage were determined, and Kappa was optimized using thresholds on probability ratios for each stage versus light sleep.Main results. Mean (SD) Kappa and accuracy for 4 sleep stages were 0.44 (0.09) and 0.65 (0.07), respectively, in healthy subjects. For 3 sleep stages (light+deep, REM, and wake), Kappa and accuracy were 0.52 (0.12) and 0.76 (0.07), respectively. Algorithm performance on data from subjects with REM behavior disorder or periodic limb movement disorder was significantly worse, with Kappa of 0.24 (0.09) and 0.36 (0.12), respectively. Average processing time by an ARM microprocessor for a 300-sample window was 19.2 ms.Significance. IBIs can be obtained from a variety of cardiac signals, including electrocardiogram, photoplethysmography, and ballistocardiography. The DNN algorithm presented is 3 orders of magnitude smaller compared with state-of-the-art algorithms and was developed to perform real-time, IBI-based sleep staging. With high specificity and moderate sensitivity for deep and REM sleep, small footprint, and causal processing, this algorithm may be used across different platforms to perform real-time sleep staging and direct intervention strategies.Novelty & Significance(92/100 words) This article describes the development and testing of a deep neural network-based algorithm to detect sleep stages using interbeat intervals, which can be obtained from a variety of cardiac signals including photoplethysmography, electrocardiogram, and ballistocardiography. Based on the interbeat intervals identified in electrocardiogram signals, the algorithm architecture included a group of convolution layers and a group of long short-term memory layers. With its small footprint, fast processing time, high specificity and good sensitivity for deep and REM sleep, this algorithm may provide a good option for real-time sleep staging to direct interventions.

Innovative approaches in investigating inter-beat intervals: Graph theoretical method suggests altered autonomic functioning in adolescents with ADHD.

Cardiac inter-beat intervals (IBIs) are considered to reflect autonomic functioning and self-regulatory abilities and are often investigated by traditional time- and frequency domain analyses. These analyses investigate IBI fluctuations across relatively long time series. The similarity graph algorithm is a nonlinear method that analyzes segments of IBI time series (i.e., time windows)-possibly being more sensitive to transient and spontaneous IBI fluctuations. We hypothesized that the similarity graph algorithm would detect differences between Attention-Deficit/Hyperactivity Disorder (ADHD) and control groups. Resting electrocardiogram (ECG) recordings were collected in 10-18-year-olds with ADHD (n = 37) and controls (n = 36). IBIs were converted to graphs that were subsequently investigated for similarity. We varied the criterion for defining IBIs as similar, assessing which setting best distinguished ADHD and control groups. Using this setting, we applied the similarity graph algorithm to time windows of 2-5, 6-13 and 12-25 s, respectively. We also performed traditional IBI analyses. Independent samples t tests assessed group differences. Results showed that a 1.5% criterion of similarity and a time window of 2-5 s best distinguished adolescents with ADHD and controls. The similarity graph algorithm showed a higher number of edges, maximum edges and cliques, and lower edges10+10/edges2+2 in the ADHD group compared to controls. The results suggested more similar IBIs in the ADHD group compared to the controls, possibly due to altered vagal activity and less effective regulation of heart rate. Traditional analyses did not detect any group differences. Consequently, the similarity graph algorithm might complement traditional IBI analyses as a marker of psychopathology.

The effect of using activity workstations on heart rate variability during complex cognitive tasks.

ObjectivesThe purpose of the current study was to examine the effects of using an activity workstation on the physiological stress response as measured by heart rate variability while completing cognitively demanding tasks. Participants: Eleven college students (6 females; age: 19.4 ± 0.9 years) participated in the study. Methods: The participants completed three psychologically stressful cognitive tasks while seated at a traditional desk and while using an activity workstation. Heart rate variability was recorded and analyzed with power spectrum density and time-domain analysis. Results: Using activity workstations while completing stressful cognitive tasks did not negatively affect task performance. There was; however, a reduction in low frequency heart rate variability but no change in cardiac sympathovagal balance. Conclusion: The results indicate that using activity workstations while completing difficult tasks reduces sympathetic reactivity to stress in college students. This suggests that using activity workstations could provide a coping mechanism for stress.

Trajectories of Heart Activity Across Infancy to Early Childhood Differentially Predict Autism and Anxiety Symptoms in Fragile X Syndrome.

Background: Fragile X syndrome (FXS) is a monogenic disorder characterized by high rates of autism spectrum disorder (ASD) and anxiety. A longstanding "hyperarousal hypothesis" in FXS has argued that ANS dysfunction underpins many symptoms of FXS. However, the developmental onset and trajectory of ANS dysfunction, as well as the consequences of ANS dysfunction on later psychiatric symptoms, remain poorly understood in FXS. Insight into the emergence, trajectory, and consequences of ANS dysfunction across early development in FXS has critical implications for prevention, intervention, and optimal outcomes in both typical and atypical development. This longitudinal study investigated whether and when males with FXS evidence atypical ANS function from infancy through early childhood, and how trajectories of ANS function across infancy and early childhood predict ASD and anxiety symptom severity later in development. Methods: Participants included 73 males with FXS and 79 age-matched typically developing (TD) males. Baseline heart activity was recorded at multiple assessments between 3 and 83 months of age, resulting in 372 observations. General arousal and parasympathetic activity were indexed via interbeat interval (IBI) and respiratory sinus arrhythmia (RSA), respectively. ASD and anxiety symptoms were assessed at 36 months of age or later in a subgroup of participants (FXS n = 28; TD n = 25). Results: Males with FXS exhibited atypical patterns of developmental change in ANS function across infancy and early childhood. As a result, ANS dysfunction became progressively more discrepant across time, with the FXS group exhibiting significantly shorter IBI and lower RSA by 29 and 24 months of age, respectively. Shorter IBI at 24 months and a flatter IBI slope across development predicted elevated anxiety symptoms, but not ASD symptoms, later in childhood in both FXS and TD males. Reduced RSA at 24 months predicted elevated ASD symptoms, but not anxiety symptoms, in both groups. Developmental change in RSA across early development did not predict later anxiety or ASD symptoms. Conclusion: This is the first longitudinal study to examine the "hyperarousal hypothesis" in infants and young children with FXS. Findings suggest that hyperarousal (i.e., shorter IBI, lower RSA) is evident in males with FXS by 24-29 months of age. Interestingly, unique aspects of early ANS function differentially relate to later ASD and anxiety symptoms. General arousal, indexed by shorter IBI that becomes progressively more discrepant from TD controls, predicts later anxiety symptoms. In contrast, parasympathetic-related factors, indexed by lower levels of RSA, predict ASD symptoms. These findings support the "hyperarousal hypothesis" in FXS, in that ANS dysfunction evident early in development predicts later-emerging symptoms of ASD and anxiety. This study also have important implications for the development of targeted treatments and interventions that could potentially mitigate the long-term effects of hyperarousal in FXS.

Higher Anxiety Is Associated with Lower Cardiovascular Autonomic Function in Female Twins.

Anxiety symptoms co-occur with cardiovascular health problems, with increasing evidence suggesting the role of autonomic dysfunction. Yet, there is limited behavior genetic research on underlying mechanisms. In this twin study, we investigated the phenotypic, genetic and environmental associations between a latent anxiety factor and three cardiovascular autonomic function factors: interbeat interval (IBI, time between heart beats), heart rate variability (HRV, overall fluctuation of heart-beat intervals) and baroreflex sensitivity (BRS, efficiency in regulating blood pressure [BP]). Multivariate twin models were fit using data of female twins (N = 250) of the Twin Interdisciplinary Neuroticism Study (TWINS). A significant negative association was identified between latent anxiety and BRS factors (r = -.24, 95% CI [-.40, -.07]). Findings suggest that this relationship was mostly explained by correlated shared environmental influences, and there was no evidence for pleiotropic genetic or unique environmental effects. We also identified negative relationships between anxiety symptoms and HRV (r = -.17, 95% CI [-.34, .00]) and IBI factors (r = -.13, 95% CI [-.29, .04]), though these associations did not reach statistical significance. Findings implicate that higher anxiety scores are associated with decreased efficiency in short-term BP regulation, providing support for autonomic dysfunction with anxiety symptomatology. The baroreflex system may be a key mechanism underlying the anxiety-cardiovascular health relationship.

A robust diving response in the laboratory mouse.

The diving response is a coordinated physiological response to submersion under water and has been documented amongst all mammals tested to date. The physiological response consists of three primary reflexes: an immediate bradycardia, apnea, and selective constriction of peripheral blood vessels. We hypothesized that mice would exhibit a diving response upon voluntary submersion into water typically seen in other mammals. In this study, telemeters that measure arterial pressure were implanted into male and female C57Bl/6J mice. These mice were trained to voluntarily dive underwater for a distance of 40 cm over a 4-6 s period. Just before the dive, the interbeat interval (IBI) was 87 ± 6 ms (mean ± SD) and diastolic pressure was 99 ± 14 mmHg. Underwater submersion caused (1) a dramatic bradycardia immediately at the onset of each dive, as IBI increased to 458 ± 104 ms, and (2) a large drop in diastolic pressure, to 56 ± 16 mmHg despite the elevation in peripheral resistance. Mice experienced a short bout (~ 2 s) of hypertension (diastolic pressure rose to 131 ± 17 mmHg) upon emergence. The bradycardia and hypotension appeared to be vagally mediated, since both these responses were blocked with atropine pre-treatment. These data demonstrate that the mouse exhibits a robust diving response upon voluntary submersion into water.

A Positive Emotional-Based Meditation but Not Mindfulness-Based Meditation Improves Emotion Regulation.

Among the various strategies for modulating the components of the emotional responses, the cognitive reappraisal and distraction are highlighted in current researches. As indicated in recent studies, the capacity for emotional regulation can be improved by mindfulness meditation practicing. This practice usually offers benefits to people's cognitive functioning and aims to improve a characteristic that is intrinsic to every human being: the ability to turn attention to the present moment. Importantly, positive emotions might also be effective on emotional regulation and several meditation practices make use of it. Thus, we aimed to compare two meditation modalities: one focused on attention only (mindfulness) and another focused-on attention toward positive emotions [Twin Hearts Meditation (THM)]. Ninety healthy subjects without any previous experience in meditation were enrolled in this experiment. Of these participants, 30 were submitted to the mindfulness practice with full attention on the observation of thoughts; 30 to the THM; and 30 to a control group (no meditation practice). After one session of meditation, all the participants completed emotional regulation task judging the valence and arousal of pictures with emotional content. In addition to the behavioral data, the participants' psychophysiological measures were recorded via electrocardiography (ECG). The results demonstrate a greater efficacy of THM in suppressing the negative valence of the negative pictures and amplifying the valence of the positive ones. No effect of meditation was observed for the ECG. Our findings indicate that contemplative meditation (THM) can positively influence the emotion regulation ability, even when performed by non-meditators and only once. However, in mindfulness meditation this same immediate effect was not found. Our findings reveal that faster effects of meditation practices can be obtained by practices that considers either the attentional processing and the positive emotions.

Quantitative Analysis of the Effect of an Ectopic Beat on the Heart Rate Variability in the Resting Condition.

The purpose of this study is to quantitatively analyze the effect of an ectopic beat on heart rate variability (HRV) in the time domain, frequency domain, and in a non-linear analysis. A quantitative analysis was carried out by generating artificial ectopic beats that probabilistically contained a missed beat or a false-detected beat, and the statistical significance was evaluated though a comparison with an ectopic-free HRV by increasing the ratio of the ectopic beat in 0.1% increments from 0 to 50%. The effect of the interpolation on the ectopic HRV was also investigated by applying nearest-neighbor interpolation, linear interpolation, and cubic spline interpolation. The results confirmed a statistically significant difference (P < 0.05) even in the less-than-1% ectopic HRV in every domain. When interpolation was applied, there were differences according to the interpolation method used, but statistical significance was secured for an ectopic beat ratio from 1 to 2% to several tens of a percent. In the effect, linear interpolation, and spline interpolation were confirmed to have a higher effect on the high-frequency related HRV variables, and nearest-neighbor interpolation had a higher effect on low-frequency related variables.

Only reappraisers profit from reappraisal instructions: Effects of instructed and habitual reappraisal on stress responses during interpersonal conflicts.

Conflicts are an undesirable yet common aspect of daily interactions with wide-ranging negative consequences. The present research aimed to examine the buffering effect of experimentally instructed reappraisal on self-reported, physiological and behavioral stress indices during interpersonal conflicts, taking into account habitual emotion regulation strategies. For this, 145 participants experienced a standardized laboratory conflict with the instruction to either reappraise (n = 48), to suppress (n = 50), or with no instruction (n = 47) while cardiovascular and neuroendocrine measures were taken. Participants were allowed to eat sweet and salty snacks during the conflict situation. Prior to as well as after the conflict, participants reported on their subjective stress level. Reappraisal instructions were only effective for high habitual reappraisers who exhibited lower cardiovascular and cortisol reactivity and demonstrated fewer snack-eating behaviors under reappraisal instructions than under suppression or no instructions. The opposite pattern emerged for low habitual reappraisers. Neither experimentally instructed nor habitual reappraisal by itself reduced the negative effects of conflicts. Our findings complement the literature on the diverging effects of instructed reappraisal in tense social interactions.

Time domain measurement of the vascular and myocardial branches of the baroreflex: A study in physically active versus sedentary individuals.

This study tests the spontaneous sequence method for the evaluation of the cardiac, vasomotor, and myocardial branches of the baroreflex. Systolic blood pressure (SBP), interbeat interval (IBI), stroke volume (SV), preejection period (PEP), and total peripheral resistance (TPR) were continuously recorded in 33 physically active and 25 sedentary participants at rest and during a mental arithmetic task. Sequences of spontaneous covariation between SBP and IBI (for the cardiac branch), SV and PEP (for the myocardial branch), and TPR (for the vasomotor branch) were located. The slope of the regression line between values in the sequences produced an estimate of baroreflex sensitivity (BRS), and the proportion of progressive SBP changes that elicited reflex modulations yielded an estimate of baroreflex effectiveness (BEI). The active group showed greater BRS in all three branches than the sedentary group. Cardiac and vasomotor BEI decreased during the arithmetic task in the sedentary group but not in the active one. Only cardiac BRS decreased during the arithmetic task. In conclusion, the method appears appropriate for the simultaneous assessment of the three baroreflex branches. The assessment of the vascular branch of the baroreflex may have prognostic relevance in the development of hypertension or other cardiometabolic diseases.

Physiological reactivity to nonideographic virtual reality stimuli in veterans with and without PTSD.

BACKGROUND: Post-traumatic stress disorder (PTSD) currently is diagnosed via clinical interview in which subjective self reports of traumatic events and associated experiences are discussed with a mental health professional. The reliability and validity of diagnoses can be improved with the use of objective physiological measures. METHODS: In this study, physiological activity was recorded from 58 male veterans (PTSD Diagnosis n = 16; Trauma Exposed/No PTSD Diagnosis: n = 23; No Trauma/No PTSD Diagnosis: n = 19) with and without PTSD and combat trauma exposure in response to emotionally evocative non-idiographic virtual reality stimuli. RESULTS: Statistically significant differences among the Control, Trauma, and PTSD groups were present during the viewing of two virtual reality videos. Skin conductance and interbeat interval features were extracted for each of ten video events (five events of increasing severity per video). These features were submitted to three stepwise discriminant function analyses to assess classification accuracy for Control versus Trauma, Control versus PTSD, and Trauma versus PTSD pairings of participant groups. Leave-one-out cross-validation classification accuracy was between 71 and 94%. CONCLUSIONS: These results are promising and suggest the utility of objective physiological measures in assisting with PTSD diagnosis.