Resting sympathetic arousal moderates the association between parasympathetic reactivity and working memory performance in adults reporting high levels of life stress

Williams D.P., Thayer J.F., Koenig J.

Intraindividual reaction time variability (IIV), defined as the variability in trial-to-trial response times, is thought to serve as an index of central nervous system function. As such, greater IIV reflects both poorer executive brain function and cognitive control, in addition to lapses in attention. Resting-state vagally mediated heart rate variability (vmHRV), a psychophysiological index of self-regulatory abilities, has been linked with executive brain function and cognitive control such that those with greater resting-state vmHRV often perform better on cognitive tasks. However, research has yet to investigate the direct relationship between resting vmHRV and task IIV. The present study sought to examine this relationship in a sample of 104 young and healthy participants who first completed a 5-min resting-baseline period during which resting-state vmHRV was assessed. Participants then completed an attentional (target detection) task, where reaction time, accuracy, and trial-to-trial IIV were obtained. Results showed resting vmHRV to be significantly related to IIV, such that lower resting vmHRV predicted higher IIV on the task, even when controlling for several covariates (including mean reaction time and accuracy). Overall, our results provide further evidence for the link between resting vmHRV and cognitive control, and extend these notions to the domain of lapses in attention, as indexed by IIV. Implications and recommendations for future research on resting vmHRV and cognition are discussed.

Clark C.A., Skowron E.A., Giuliano R.J., Fisher P.A.

Early childhood is characterized by dramatic gains in emotion regulation skills that support social adjustment and mental health. Understanding the physiological substrates of healthy emotion regulation may offer new directions for altering trajectories toward initiation and escalation of substance abuse. Here, we describe the intersections between parasympathetic and sympathetic tone, emotion regulation and prosocial behavior in a high-risk sample of preschoolers.Fifty-two 3-6 year old children completed an assessment of attention regulation in response to affective stimuli. Cardiac respiratory sinus arrhythmia, an index of parasympathetic tone, and pre-ejection period, a marker of sympathetic activation, were recorded at rest and while children engaged in social interactions with their mothers and an unfamiliar research assistant. Mothers reported on children's emotional reactivity and prosocial behavior.Controlling for age and psychosocial risk, higher parasympathetic tone predicted better attention regulation in response to angry emotion and higher levels of prosocial behavior, whereas a reciprocal pattern of higher parasympathetic tone and lower sympathetic arousal predicted better attention in response to positive emotion and lower emotional reactivity. Children exposed to fewer risk factors and higher levels of maternal warmth were more able to sustain a high level of parasympathetic tone during interaction episodes.Findings suggest that autonomic measures represent biomarkers for socio-emotional competence in young children. They also point to the importance of early experiences in the establishment of physiological regulation and the promise of family-based intervention to promote healthy emotion regulation and prevent substance dependence in high-risk populations.

Gatzke-Kopp L.M.

This Special Issue is devoted to the illustration and discussion of three key demographic variables (sex/gender, race/ethnicity, and socioeconomic status) that have been shown to moderate associations between psychophysiological processes and behavior. The introduction to the issue discusses the role of phenotypic plasticity in the emergence of different neural processes that achieve the same behavioral outcome, with emphasis on how these relatively stable developmental contexts affect brain/behavior associations without necessarily resulting in difference in behavior. These findings have profound significance for the implications of generalization and call into question the presumption that diverse samples produce an average result that is appropriately reflective of the individuals themselves. Increasing diversity within psychophysiological research is critical in elucidating mechanisms by which the human brain can accomplish cognitive and affective behaviors. This article further examines the logistical and ethical challenges faced in achieving this goal.

Crouch J.L., Hiraoka R., McCanne T.R., Reo G., Wagner M.F., Krauss A., Milner J.S., Skowronski J.J.

The present study examined heart rate and heart rate variability (i.e., respiratory sinus arrhythmia [RSA]) in a sample of 48 general population parents (41.7% fathers), who were either at high risk ( n = 24) or low risk ( n = 24) for child physical abuse. During baseline assessments of heart rate and RSA, parents sat quietly for 3 min. Afterward, parents were presented with a series of anagrams (either easy or difficult) and were instructed to solve as many anagrams as possible in 3 min. As expected, high-risk (compared with low-risk) parents evinced significantly higher resting heart rate and significantly lower resting RSA. During the anagram task, high-risk parents did not evince significant changes in heart rate or RSA relative to baseline levels. In contrast, low-risk parents evinced significant increases in heart rate and significant decreases in RSA during the anagram task. Contrary to expectations, the anagram task difficulty did not moderate the study findings. Collectively, this pattern of results is consistent with the notion that high-risk parents have chronically higher levels of physiological arousal relative to low-risk parents and exhibit less physiological flexibility in response to environmental demands. High-risk parents may benefit from interventions that include components that reduce physiological arousal and increase the capacity to regulate arousal effectively.

Beauchaine T.P., Thayer J.F.

The Research Domain Criteria (RDoC), developed by the National Institute of Mental Health as a neuroscience-informed alternative to traditional psychiatric nosology, is an explicitly dimensional system in which classification of psychopathology is derived inductively (i.e., from basic science), across multiple levels of analysis (e.g., genetic, neural, psychophysiological, and behavioral). Although RDoC is often presented as paradigmatically revolutionary, a review of the history of psychophysiology suggests that roots of RDoC thinking extend at least as far back as the mid-20th Century. In this paper, we briefly and selectively review the historical emergence of neurobiologically-informed dimensional trait models of psychopathology, and we summarize our thinking regarding high frequency heart rate variability (HF-HRV) as a transdiagnostic biomarker of self-regulation and cognitive control. When functional interactions between HF-HRV and systems of behavioral approach and avoidance are considered, diverse patterns of behavioral maladjustment can be subsumed into a single model. This model accommodates the general bifactor structure of psychopathology, and suggests that HF-HRV can be viewed as an autonomic, transdiagnostic biomarker of mental illness.

Shields G.S., Bonner J.C., Moons W.G.

The hormone cortisol is often believed to play a pivotal role in the effects of stress on human cognition. This meta-analysis is an attempt to determine the effects of acute cortisol administration on core executive functions. Drawing on both rodent and stress literatures, we hypothesized that acute cortisol administration would impair working memory and set-shifting but enhance inhibition. Additionally, because cortisol is thought to exert different nongenomic (rapid) and genomic (slow) effects, we further hypothesized that the effects of cortisol would differ as a function of the delay between cortisol administration and cognitive testing. Although the overall analyses were nonsignificant, after separating the rapid, nongenomic effects of cortisol from the slower, genomic effects of cortisol, the rapid effects of cortisol enhanced response inhibition, g+ = 0.113, p=.016, but impaired working memory, g+ = -0.315, p=.008, although these effects reversed over time. Contrary to our hypotheses, there was no effect of cortisol administration on set-shifting. Thus, although we did not find support for the idea that increases in cortisol influence set-shifting, we found that acute increases in cortisol exert differential effects on working memory and inhibition over time.

Bray E.E., MacLean E.L., Hare B.A.

The emotional-reactivity hypothesis proposes that problem-solving abilities can be constrained by temperament, within and across species. One way to test this hypothesis is with the predictions of the Yerkes–Dodson law. The law posits that arousal level, a component of temperament, affects problem solving in an inverted U-shaped relationship: Optimal performance is reached at intermediate levels of arousal and impeded by high and low levels. Thus, a powerful test of the emotional-reactivity hypothesis is to compare cognitive performance in dog populations that have been bred and trained based in part on their arousal levels. We therefore compared a group of pet dogs to a group of assistance dogs bred and trained for low arousal (N = 106) on a task of inhibitory control involving a detour response. Consistent with the Yerkes–Dodson law, assistance dogs, which began the test with lower levels of baseline arousal, showed improvements when arousal was artificially increased. In contrast, pet dogs, which began the test with higher levels of baseline arousal, were negatively affected when their arousal was increased. Furthermore, the dogs’ baseline levels of arousal, as measured in their rate of tail wagging, differed by population in the expected directions. Low-arousal assistance dogs showed the most inhibition in a detour task when humans eagerly encouraged them, while more highly aroused pet dogs performed worst on the same task with strong encouragement. Our findings support the hypothesis that selection on temperament can have important implications for cognitive performance.

Crandall A., Deater-Deckard K., Riley A.W.

Emerging evidence suggests that maternal emotion and cognitive control capacities are critical to the development and maintenance of parenting practices and may be related to parents' ability to seek and use parenting help. The purpose of this paper is to present a cohesive conceptual framework on the intersection of maternal emotion and cognitive control capacities and parenting based on a review of literature.We conducted a comprehensive literature review of articles published between 2000 and February 2014 that addressed maternal emotion and cognitive control and parenting. The 35 articles identified were assigned a methodological quality score.Low maternal emotion and cognitive control capacity is associated with increased risk of engaging in child maltreatment, whereas higher maternal emotion and cognitive regulation is associated with sensitive, involved parenting. Contextual factors, such as SES and household organization, play a complex and not clearly understood role on the association between maternal cognitive control and parenting. A conceptual framework was developed based on the results of the literature review.The conceptual framework developed can be used to inform future research and practice. Longitudinal studies that assess the temporal relationship of maternal emotion and cognitive control and parenting are necessary to establish causality. Research that addresses how maternal emotion regulation and cognitive control capacities are related to mothers' enrollment and participation in parenting and early intervention programs is an important next step to strengthening policy and intervention work.

Capuana L.J., Dywan J., Tays W.J., Elmers J.L., Witherspoon R., Segalowitz S.J.

Working from a model of neurovisceral integration, we examined whether adding response contingencies and motivational involvement would increase the need for cardiac autonomic regulation in maintaining effective cognitive control. Respiratory sinus arrhythmia (RSA) was recorded during variants of the Stroop color-word task. The Basic task involved "accepting" congruent items and "rejecting" words printed in incongruent colors (BLUE in red font); an added contingency involved rejecting a particular congruent word (e.g., RED in red font), or a congruent word repeated on an immediately subsequent trial. Motivation was increased by adding a financial incentive phase. Results indicate that pre-task RSA predicted accuracy best when response contingencies required the maintenance of a specific item in memory or on the Basic Stroop task when errors resulted in financial loss. Overall, RSA appeared to be most relevant to performance when the task encouraged a more proactive style of cognitive control, a control strategy thought to be more metabolically costly, and hence, more reliant on flexible cardiac autonomic regulation.

Jennings J.R., Allen B., Gianaros P.J., Thayer J.F., Manuck S.B.

Giuliano R.J., Karns C.M., Neville H.J., Hillyard S.A.

Abstract A growing body of research suggests that the predictive power of working memory (WM) capacity for measures of intellectual aptitude is due to the ability to control attention and select relevant information. Crucially, attentional mechanisms implicated in controlling access to WM are assumed to be domain-general, yet reports of enhanced attentional abilities in individuals with larger WM capacities are primarily within the visual domain. Here, we directly test the link between WM capacity and early attentional gating across sensory domains, hypothesizing that measures of visual WM capacity should predict an individual's capacity to allocate auditory selective attention. To address this question, auditory ERPs were recorded in a linguistic dichotic listening task, and individual differences in ERP modulations by attention were correlated with estimates of WM capacity obtained in a separate visual change detection task. Auditory selective attention enhanced ERP amplitudes at an early latency (ca. 70–90 msec), with larger P1 components elicited by linguistic probes embedded in an attended narrative. Moreover, this effect was associated with greater individual estimates of visual WM capacity. These findings support the view that domain-general attentional control mechanisms underlie the wide variation of WM capacity across individuals.

Pike J.L., Smith T.L., Hauger R.L., Nicassio P.M., Patterson T.L., McClintick J., Costlow C., Irwin M.R.

Life stress is hypothesized to alter the dynamic regulation of the autonomic, neuroendocrine, and immune systems. This study examined the effects of antecedent chronic life stress on psychological and physiological responsivity after acute challenge with a psychological stressor.Using a within-subject mixed design, male volunteers with (N = 12) and without chronic life stress (N = 11) were administered a 12-minute laboratory stressor (mental arithmetic) vs a video control.Acute psychological stress induced subjective distress, increases of circulating concentrations of epinephrine, norepinephrine, beta-endorphin, adrenocorticotropic hormone (ACTH), and cortisol, and a selective redistribution of natural killer (NK) cells into the peripheral blood as compared with the video control condition. Although the two groups were almost identical at baseline in psychological, sympathetic, neuroendocrine, and immune domains, the chronic stress group showed greater subjective distress, higher peak levels of epinephrine, lower peak levels of beta-endorphin and of NK cell lysis, and a more pronounced redistribution of NK cells in response to the acute psychological challenge than the controls. Furthermore, the acute stressor induced a protracted decline in NK lysis per NK cell in the chronic stress group but had no effect in the controls.In summary, when persons who are undergoing chronic life stress are confronted with an acute psychological challenge, an exaggerated psychologic and peak sympathomedullary reactivity occurs that is associated with decrements in individual NK cell function and is protracted beyond termination of the stressor and sympathomedullary recovery.

Overbeek T.J., van Boxtel A., Westerink J.H.

Many studies show that respiratory sinus arrhythmia (RSA) decreases while performing cognitive tasks. However, there is uncertainty about the role of contaminating factors such as physical activity and stress-inducing task variables. Different methods to quantify RSA may also contribute to variable results. In 83 healthy subjects, we studied RSA responses to a working memory task requiring varying levels of cognitive control and a perceptual attention task not requiring strong cognitive control. RSA responses were quantified in the time and frequency domain and were additionally corrected for differences in mean interbeat interval and respiration rate, resulting in eight different RSA indices. The two tasks were clearly differentiated by heart rate and facial EMG reference measures. Cognitive control induced inhibition of RSA whereas perceptual attention generally did not. However, the results show several differences between different RSA indices, emphasizing the importance of methodological variables. Age and sex did not influence the results.

Park G., Thayer J.F.

The neurovisceral integration model (Thayer & Lane, 2000) posits that cardiac vagal tone, indexed by heart rate variability (HRV), can indicate the functional integrity of the neural networks implicated in emotion-cognition interactions. Our recent findings begin to disentangle how HRV is associated with both top-down and bottom-up cognitive processing of emotional stimuli. Higher resting HRV is associated with more adaptive and functional top-down and bottom-up cognitive modulation of emotional stimuli, which may facilitate effective emotion regulation. Conversely, lower resting HRV is associated with hyper-vigilant and maladaptive cognitive responses to emotional stimuli, which may impede emotion regulation. In the present paper, we recapitulate the neurovisceral integration model and review recent findings that shed light on the relationship between HRV and top-down and bottom-up visual perception and attention to emotional stimuli, which may play an important role in emotion regulation. Further implications of HRV on individual well-being and mental health are discussed.

Park G., Vasey M.W., Van Bavel J.J., Thayer J.F.

We examined the relationship between tonic—a correlate of self-regulatory functioning—and phasic cardiac vagal activity (indexed by heart rate variability; HRV) during a selective attentional task with varying levels of load. Participants detected a target letter among letter strings superimposed on either fearful or neutral face distractors. Letter strings consisted of six target letters under low load and one target letter and five nontarget letters under high load. With fearful distractors, lower tonic HRV was associated with phasic HRV suppression, suggesting an autonomic stress response under both low and high load. In contrast, higher tonic HRV was associated with phasic HRV enhancement, suggesting greater self-regulatory effort under low load and an absence of phasic HRV suppression under high load. The current research suggests that tonic cardiac vagal tone is associated with the ability to flexibly adapt autonomic responses.

Doneda M., Borsa V.M., Brugnera A., Compare A., Rusconi M.L., Sakatani K., Lanzarone E.

Abstract: Performance efficiency in cognitive tasks is a combination of effectiveness, that is, accuracy, and cognitive effort. Resting-state and task-related autonomic and cortical activity, together with psychological variables, may represent effective predictors of performance efficiency. This study aimed to investigate the impact of these variables in the prediction of performance during a set of cognitive tasks in a sample of young adults. The 76 participants (age: 23.96 ± 2.69 years; 51.3% females) who volunteered for this study completed several psychological questionnaires and performed a set of attention and executive functions tasks. Resting-state and task-related prefrontal and autonomic activity were collected through a Time-Domain and a Continuous Wave 2-channel Functional Near-Infrared Spectroscopy (fNIRS) and a portable Electrocardiogram (ECG) monitoring system, respectively. A set of Machine Learning (ML) approaches were employed to (i) predict the performance of each cognitive task, while minimizing and quantifying the prediction error, and to (ii) quantitatively evaluate the predictors that most affected the cognitive outcome. Results showed that perfectionistic traits, as well as both resting-state and task-related autonomic and cortical activity, predicted performance for most of the tasks, partially supporting previous evidence. Our results add to the knowledge of psycho-physiological determinants of performance efficiency in cognitive tasks and provide preliminary evidence on the role of ML approaches in detecting important predictors in cognitive neuroscience.

Merritt S.H., Krouse M., Alogaily R.S., Zak P.J.

The elderly have an elevated risk of clinical depression because of isolation from family and friends and a reticence to report their emotional states. The present study explored whether data from a commercial neuroscience platform could predict low mood and low energy in members of a retirement community. Neurophysiologic data were collected continuously for three weeks at 1Hz and averaged into hourly and daily measures, while mood and energy were captured with self-reports. Two neurophysiologic measures averaged over a day predicted low mood and low energy with 68% and 75% accuracy. Principal components analysis showed that neurologic variables were statistically associated with mood and energy two days in advance. Applying machine learning to hourly data classified low mood and low energy with 99% and 98% accuracy. Two-day lagged hourly neurophysiologic data predicted low mood and low energy with 98% and 96% accuracy. This study demonstrates that continuous measurement of neurophysiologic variables may be an effective way to reduce the incidence of mood disorders in vulnerable people by identifying when interventions are needed.

Kerley L., Meredith P., Harnett P.

Introduction Autonomic nervous system functioning is theorised to underpin individual differences in sensory processing, with a small amount of supporting evidence. Despite recognition of the need to measure the balance between sympathetic and parasympathetic activity, most studies have measured only one of these systems. This study investigated whether sensory processing patterns are related to autonomic balance for young adults at rest and in response to a sensory-based stressor. Method In this cross-sectional laboratory study, 100 young adults completed the adolescent/adult sensory profile. Heart rate variability and pre-ejection period were recorded before, during and after a coldpressor task. Results Relationships between sensory processing patterns and autonomic balance varied by gender. In males, low sensory thresholds were generally related to a state of reciprocal sympathetic activation. In females, low thresholds were associated with greater autonomic reactivity in response to the coldpressor. Conclusion This study showed, for the first time in young adults, that sensory processing patterns may be linked to patterns of autonomic balance. Therapists should be aware that young men with low sensory thresholds may be more likely than others to exhibit a resting state of sympathetic hyperarousal and further research should investigate whether this impacts their daily functioning and wellbeing.

Barbic F., Minonzio M., Cairo B., Shiffer D., Cerina L., Verzeletti P., Badilini F., Vaglio M., Porta A., Santambrogio M., Gatti R., Rigo S., Bisoglio A., Furlan R.

An inverted U-shape relationship between cognitive performance and indoor temperature with best performance peaking at 21.6 °C was previously described. Little is known on classroom temperature reduction effects on cognitive performances and cardiac autonomic profile, during the cold season. Fifteen students underwent electrocardiogram recording during a lecture in two days in December when classroom temperatures were set as neutral (NEUTRAL, 20-22 °C) and cool (COOL, 16-18 °C). Cognitive performance (memory, verbal ability, reasoning, overall cognitive C-score) was assessed by Cambridge Brain Science cognitive evaluation tool. Cardiac autonomic control was evaluated via the analysis of spontaneous fluctuations of heart period, as the temporal distance between two successive R-wave peaks (RR). Spectral analysis provided the power in the high frequency (HF, 0.15-0.40 Hz) and low frequency (LF, 0.04-0.15 Hz) bands of RR variability. Sympatho-vagal interaction was assessed by LF to HF ratio (LF/HF). Symbolic analysis provided the fraction of RR patterns composed by three heart periods with no variation (0 V%) and two variations (2 V%), taken as markers of cardiac sympathetic and vagal modulations, respectively. The students' thermal comfort was assessed during NEUTRAL and COOL trials. Classroom temperatures were 21.5 ± 0.8 °C and 18.4 ± 0.4 °C during NEUTRAL and COOL. Memory, verbal ability, C-Score were greater during COOL (13.01 ± 3.43, 12.32 ± 2.58, 14.29 ± 2.90) compared to NEUTRAL (9.98 ± 2.26, p = 0.002; 8.57 ± 1.07, p = 0.001 and 10.35 ± 3.20, p = 0.001). LF/HF (2.4 ± 1.7) and 0 V% (23.2 ± 11.1%) were lower during COOL compared to NEUTRAL (3.7 ± 2.8, p = 0.042; 28.1 ± 12.2.1%, p = 0.031). During COOL, 2 V% was greater (30.5 ± 10.9%) compared to NEUTRAL (26.2 ± 11.3, p = 0.047). The students' thermal comfort was slightly reduced during COOL compared to NEUTRAL trial. During cold season, a better cognitive performance was obtained in a cooler indoor setting enabling therefore energy saving too.

Fry C.M., Ram N., Gatzke-Kopp L.M.

Autonomic nervous system activity flexibly shifts and modulates behavior at multiple time scales, with some work suggesting that patterns of short-term reactivity contribute to long-term developmental change. However, previous work has largely considered sympathetic and parasympathetic systems independently, even though both systems contribute dynamically to the regulation of physiological arousal. Using physiological data obtained from 313 children in kindergarten, 1st, and 2nd grade we examined whether within-person autonomic coordination during an emotion-inducing film task in kindergarten was associated with developmental change in resting autonomic activity. On average, these kindergarteners exhibited reciprocal coordination during the approach-oriented emotion (angry, happy) condition and a lack of coordination during the avoidance-oriented emotion (fear, sad) condition. Alignment with these patterns was associated with more typical autonomic development, specifically an increase in resting respiratory sinus arrhythmia (RSA) and a decrease in resting skin conductance (SCR) from kindergarten to 2nd grade; while lack of coordination during the approach condition was associated with a relatively delayed increase in resting RSA and a steeper decline in SCR, and reciprocal coordination during the avoidance condition was associated with a lack of RSA increase. Findings highlight the need for additional consideration of how moment-to-moment dynamics of autonomic coordination influence longer-term development, and suggest that early patterns of atypical arousal may portend dysregulation of developing physiological systems.

Plain B., Pielage H., Richter M., Bhuiyan T.A., Lunner T., Kramer S.E., Zekveld A.A.

Certain cardiovascular measures allow for distinction between sympathetic and parasympathetic nervous system activity. Applied during listening, these measures may provide a novel and complementary insight into listening effort. To date, few studies have implemented cardiovascular measures of listening effort and seldom have these included hearing-impaired participants. These studies have generally measured changes in cardiovascular parameters while manipulating environmental factors, such as listening difficulty. Yet, listening effort is also known to be moderated by individual factors, including the importance of performing successfully. In this study, we aimed to manipulate success importance by adding observers to the traditional laboratory set-up. Twenty-nine hearing-impaired participants performed a speech reception task both alone and in the presence of two observers. Auditory stimuli consisted of Danish Hearing in Noise Test (HINT) sentences masked by four-talker babble. Sentences were delivered at two individually adapted signal-to-noise ratios, corresponding to 50 and 80% of sentences correct. We measured change scores, relative to baseline, of pre-ejection period, two indices of heart rate variability, heart rate and blood pressure (systolic, diastolic, and mean arterial pressure). After each condition, participants rated their effort investment, stress, tendency to give up and preference to change the situation to improve audibility. A multivariate analysis revealed that cardiovascular reactivity increased in the presence of the observers, compared to when the task was performed alone. More specifically, systolic, diastolic, and mean arterial blood pressure increased while observed. Interestingly, participants' subjective ratings were sensitive only to intelligibility level, not the observation state. This study was the first to report results from a range of different cardiovascular variables measured from hearing-impaired participants during a speech reception task. Due to the timing of the observers' presence, we were not able to conclusively attribute these physiological changes to being task related. Therefore, instead of representing listening effort, we suggest that the increased cardiovascular response detected during observation reveals increased physiological stress associated with potential evaluation.

Corrigan S.L., Roberts S., Warmington S., Drain J., Main L.C.

Awareness of the cumulative stress placed on first responders and tactical operators is required to manage acute fatigue, which can impair occupational performance, and may precipitate negative chronic health outcomes. The aim of this review was to investigate the utility of heart rate variability (HRV) to monitor stress and allostatic load among these populations. A systematic search of Academic Search Complete, MEDLINE complete, PsycINFO, SPORTDiscus and Scopus databases was conducted. Eligibility criteria: original peer reviewed research articles, written in English, published between 1985 and 2020, using human participants employed as a first responder or tactical operator, free from any psychological disorder. Of the 360 articles screened, 60 met the inclusion criteria and were included for full text assessment. Articles were classified based on single or repeated stressor exposure and the time of HRV assessment (baseline, during stressor, post stressor). Singular stressful events elicited a reduction in HRV from baseline to during the event. Stressors of greater magnitude reduced HRV for extended durations post stressor. Lower resting HRV was associated with lower situational awareness and impaired decision-making performance in marksmanship and navigation tasks. There were insufficient studies to evaluate the utility of HRV to assess allostatic load in repeated stressor contexts. A reduction in HRV occurred in response to acute physical and cognitive occupational stressors. A slower rate of recovery of HRV after the completion of acute occupational stressors appears to occur in response to stressors of greater magnitude. The association between lower HRV and lower decision-making performance poses as a useful tool but further investigations on within subject changes between these factors and their relationship is required. More research is required to investigate the suitability of HRV as a measure of allostatic load in repeated stress exposures for fatigue management in first responder and tactical operators.

Gordon I., Horesh D., Milstein N., Tomashin A., Mayo O., Korisky A.

Despite the unfolding impact of the COVID-19 pandemic on psychological well-being, there is a lack of prospective studies that target physiological markers of distress. There is a need to examine physiological predictors from the pre-pandemic period to identify and treat individuals at-risk. In this study, our aim was to use pre-pandemic markers of autonomic nervous system (ANS) parasympathetic and sympathetic regulation to predict individuals' psychological well-being during the crisis. We also assessed the role of mood regulation expectancies as a mediator of the association between pre-pandemic physiological measures and COVID-related well-being. In May to June 2020, 185 Israeli adults completed online questionnaires assessing their mood regulation expectancies since COVID-19 began, and their current well-being. These individuals had participated in lab studies 1.5-3 years prior to this assessment, where their physiological measures were taken, including respiratory sinus arrhythmia (RSA) and skin conductance level (SCL). RSA was positively related to mood regulation expectancies during COVID-19 (b = 3.46, 95% CI [0.84, 6.05]). Mood regulation expectancies, in turn, positively predicted well-being during the crisis (b = 0.021, 95% CI [0.016, 0.027]). The mediation was significant and moderated by SCL (index = -0.09, 95% CI [-0.02, -0.0001]), such that it was strongest for individuals with low SCL. We point to pre-pandemic physiological mechanisms underlying individuals' mental well-being during the COVID-19 pandemic. These findings have theoretical, diagnostic, and clinical implications that may refine our understanding of the physiological basis of resilience to the COVID-19 pandemic and thus may be implemented to identify and assist individuals in these times.

McIntosh R.C., Khambaty T., Llabre M.M., Perreira K.M., Gonzalez H.M., Kansal M.M., Tarraf W., Schneiderman N.

Chronic stress has a deleterious effect on prefrontal lobe functioning. Empirical evidence suggests elevated vagal tone, indexed by elevated heart rate variability (HRV), mitigates the effect of mental stress on frontal lobe function. Here, the mitigating effect of HRV on stress-related decrements in cognitive performance is assessed based on information processing speed (DSST), word fluency and verbal learning task performance. Artifact free electrocardiogram (ECG) data was analyzed from 1420 Hispanic/Latino adults from the Sociocultural Ancillary of the Hispanic Community Health Study/Study of Latinos (HCHS/SOL). A 12-lead ECG was used to collect short-term recordings of the root mean square of successive differences in all normal R-peak to R-peak intervals (RMSSD) and the change between adjacent beats and the standard deviation of those intervals (SDNN) as indices of total HRV. As predicted, an interaction emerged for HRV and stress on the task presumed to require the greatest prefrontal lobe involvement, i.e., the DSST. After accounting for sociodemographic factors, chronic stress was associated with better DSST performance amongst individuals at higher quartile of SDNN, but not RMSSD. The paradoxical effect for greater stress exposure on DSST performance may in part be explained by increased speed of information processing and decision making often reported in high-stress cohorts. The nature of this interaction highlights the importance of examining the relationship between stress and cognition across a spectrum of vagal tone.

Yang Y., Hu L., Zhang R., Zhu X., Wang M.

An increase in temperature and change of correlated color temperature (CCT) would affect cognitive performance and human physiology. Moreover, the effect of CCT on thermal sensation at different temperatures is controversial and needs to be further explored. In order to study the effects of CCT variations on students' short-term memory performance and thermal sensation, 20 subjects were exposed to a “neutral temperature” (26 °C) and two “slightly warm temperature” (28 °C, 30 °C) in different periods. In each period, short-term memory tests were assessed under different CCT (3000 K, 4500 K, and 6000 K), and subsequently completed the questionnaire about their thermal sensation. Subjects’ short-term memory performance was assessed using the N-back memory tool, the thermal sensation was evaluated using a seven-point scale while undergoing electrocardiogram (ECG) continuous recording by PowerLab. Spectral analysis of ECG provided indices of heart rate variability (HRV). The results indicate the short-term memory performance was not significantly affected by temperature and CCT. In addition, the results indicate the short-term memory performance was not significantly affected by temperature and CCT. The effect of CCT over thermal sensation was weaker compared with the temperature effect. There was a significant negative correlation between CCT and thermal sensation at 26 °C and 28 °C. When the temperature difference is 2 °C, CCT would change the dominance of temperature on thermal sensation. When the temperature remained the same and the CCT difference reached 3000 K, there was a significant difference in thermal sensation. Moreover, the effect of CCT over thermal sensation was consistent with “Hue-heat” hypothesis. HRV could be used to evaluate short-term memory performance and thermal sensation. • The short-term memory is not affected by temperature and CCT within acceptable range. • A significant negative correlation exists between CCT and thermal sensation. • CCT could dominate the thermal sensation within comfort range (26 °C–28 °C). • HRV could be used to evaluate short-term memory performance and thermal sensation. • The thermal environment is accepted when the HRV value is close to 1.

Salisbury M.R., Stienwandt S., Giuliano R., Penner-Goeke L., Fisher P.A., Roos L.E.

This study examined children's stress system reactivity via the autonomic nervous system (ANS) and hypothalamic pituitary adrenal axis (HPAA) during an acute stressor as moderators of predicted relations between cumulative risk (CR) and mental health symptoms in a sociodemographically diverse sample of young children (n = 58). We employed a reliable stressor paradigm to allow assessment of individual differences in respiratory sinus arrhythmia (RSA) and pre-ejection period (PEP), indexing ANS reactivity, and salivary cortisol, indexing HPAA reactivity. Children's behaviours were assessed using the Child Behaviour Checklist (CBCL). Cumulative risk was indexed by eight parent-reported sociodemographic and psychosocial risk factors. There was a significant main effect of CR on externalizing but not internalizing behaviours. Significant moderations emerged showing that among children with high CR, less RSA withdrawal during the acute stressor and less cortisol recovery following the stressor were associated with to greater externalizing behaviours. Among children with low CR, RSA and cortisol recovery were unrelated to internalizing or externalizing symptoms. Cortisol and PEP reactivity were not significant moderators. Results highlight the relevance of stress system function for understanding differential susceptibility to the early emergence of externalizing symptoms, linked to cumulative risk exposure.

Roddick C.M., Chen F.S.

Abstract Background Loneliness, the subjective experience of social isolation, represents one of the largest risk factors for physical illness and early death in humans. However, the mechanisms by which loneliness leads to adverse health outcomes are not well understood. Purpose In this study, we examined altered parasympathetic nervous system function as a potential pathway by which chronic loneliness and state loneliness may “get under the skin” to impact cardiovascular physiology. Methods In a controlled laboratory setting, vagally mediated resting heart rate variability (HRV), HRV reactivity to an induction of state loneliness, and HRV reactivity to a cognitive challenge task were assessed in a sample of 316 healthy women (18–28 years). Results Greater chronic loneliness in women predicted lower resting HRV, an independent risk factor for cardiovascular disease and all-cause mortality, after controlling for demographic, psychosocial, and health behavior covariates. Furthermore, women higher in chronic loneliness experienced significantly larger increases in HRV to state loneliness and reported significantly higher levels of negative affect immediately following state loneliness, compared with their less chronically lonely counterparts. Chronic loneliness also predicted blunted HRV reactivity—a maladaptive physiological response—to cognitive challenge. Conclusions The current findings provide evidence that chronic loneliness is associated with altered parasympathetic function (both resting HRV and HRV reactivity) in women, and that the immediate experience of state loneliness is linked to a proximate increase in HRV among chronically lonely women. Results are discussed in terms of implications for cardiovascular health and the evolutionary functions of loneliness.

Knight E.L., Giuliano R.J., Shank S.W., Clarke M.M., Almeida D.M.

The two branches of the autonomic nervous system (ANS) have been individually linked to changes in cognitive functioning: The parasympathetic nervous system (PNS) has been associated with healthy cognitive aging, whereas excessive sympathetic nervous system (SNS) activity has been linked to heightened cognitive decline. Despite these separate findings and despite the integrative nature of the ANS, little work has examined the two branches simultaneously to better understand their interactive effects on changes in cognitive functioning in midlife adults. We examined cognitive change in two waves of the Midlife in the United States (MIDUS) study cognitive project and indexed PNS and SNS activity from heart rate variability and epinephrine levels, respectively, from the MIDUS biomarker project (minimum n = 843, 57.9% female, mean age at first wave = 53.8 years). Our findings indicate that greater PNS responsivity (i.e., greater withdrawal and greater recovery) in response to cognitive challenge is associated with attenuated cognitive decline, but only among individuals with low SNS levels; at higher SNS levels, the effects of the PNS on cognitive decline are attenuated. These results suggest that future research targeting the ANS and cognitive aging should consider both ANS branch's effects simultaneously.

Chen P., Whitehurst L.N., Naji M., Mednick S.C.

Abstract Recent investigations have implicated the parasympathetic branch of the autonomic nervous system in higher-order executive functions. These actions are purported to occur through autonomic nervous system's modulation of the pFC, with parasympathetic activity during wake associated with working memory (WM) ability. Compared with wake, sleep is a period with substantially greater parasympathetic tone. Recent work has reported that sleep may also contribute to improvement in WM. Here, we examined the role of cardiac parasympathetic activity during sleep on WM improvement in healthy young adults. Participants were tested in an operation span task in the morning and evening, and during the intertest period, participants experienced either a nap or wake. We measured high-frequency heart rate variability as an index of cardiac, parasympathetic activity during both wake and sleep. Participants showed the expected boost in parasympathetic activity during nap, compared with wake. Furthermore, parasympathetic activity during sleep, but not wake, was significantly correlated with WM improvement. Together, these results indicate that the natural boost in parasympathetic activity during sleep may benefit gains in prefrontal executive function in young adults. We present a conceptual model illustrating the interaction between sleep, autonomic activity, and prefrontal brain function and highlight open research questions that will facilitate understanding of the factors that contribute to executive abilities in young adults as well as in cognitive aging.

Gatzke‐Kopp L.M., Benson L., Ryan P.J., Ram N.

Although anatomical research clearly demonstrates the ability of the sympathetic and parasympathetic branches of the autonomic nervous system to independently influence cardiac function, little research has examined whether coordinated activation is typical or whether the extent of autonomic coordination is situationally dependent. This study examines the extent of coordination between sympathetic (cardiac pre-ejection period: PEP) and parasympathetic (respiratory sinus arrhythmia: RSA) influences on the cardiac function to determine whether coordination is a trait-like between-person characteristic or a state-varying within-person phenomenon, and if so, whether variability in autonomic coordination is modulated by cognitive (P3b amplitude) or affective state. Kindergarten-aged children (n = 257) completed a go/no-go task administered in blocks designed to induce affective states through the delivery of reward (Blocks 1 and 3) and frustration (Block 2). Results from multilevel models that allowed for the simultaneous examination of between-person and within-person associations in the repeated measures data suggested that (a) children with higher overall RSA also tended to have higher overall PEP; (b) at within-person level, RSA and PEP tended to be reciprocally coordinated; but that (c) when frustration invokes cognitive disengagement, coordination between parasympathetic and sympathetic systems demonstrate compensatory coordination. These findings highlight the extent to which the coordination of autonomic systems is a dynamic state-like phenomenon rather than a trait-like individual differences characteristic.