The heart contracts to reward: monetary incentives and preejection period

A Multimodal Approach to Measuring Listening Effort: A Systematic Review on the Effects of Auditory Task Demand on Physiological Measures and Their Relationship

OBJECTIVES

Listening effort involves the mental effort required to perceive an auditory stimulus, for example in noisy environments. Prolonged increased listening effort, for example due to impaired hearing ability, may increase risk of health complications. It is therefore important to identify valid and sensitive measures of listening effort. Physiological measures have been shown to be sensitive to auditory task demand manipulations and are considered to reflect changes in listening effort. Such measures include pupil dilation, alpha power, skin conductance level, and heart rate variability. The aim of the current systematic review was to provide an overview of studies to listening effort that used multiple physiological measures. The two main questions were: (1) what is the effect of changes in auditory task demand on simultaneously acquired physiological measures from various modalities? and (2) what is the relationship between the responses in these physiological measures?

DESIGN

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, relevant articles were sought in PubMed, PsycInfo, and Web of Science and by examining the references of included articles. Search iterations with different combinations of psychophysiological measures were performed in conjunction with listening effort-related search terms. Quality was assessed using the Appraisal Tool for Cross-Sectional Studies.

RESULTS

A total of 297 articles were identified from three databases, of which 27 were included. One additional article was identified from reference lists. Of the total 28 included articles, 16 included an analysis regarding the relationship between the physiological measures. The overall quality of the included studies was reasonable.

CONCLUSIONS

The included studies showed that most of the physiological measures either show no effect to auditory task demand manipulations or a consistent effect in the expected direction. For example, pupil dilation increased, pre-ejection period decreased, and skin conductance level increased with increasing auditory task demand. Most of the relationships between the responses of these physiological measures were nonsignificant or weak. The physiological measures varied in their sensitivity to auditory task demand manipulations. One of the identified knowledge gaps was that the included studies mostly used tasks with high-performance levels, resulting in an underrepresentation of the physiological changes at lower performance levels. This makes it difficult to capture how the physiological responses behave across the full psychometric curve. Our results support the Framework for Understanding Effortful Listening and the need for a multimodal approach to listening effort. We furthermore discuss focus points for future studies.

Analysing experienced and inexperienced cyclists' attentional focus and self-regulatory strategies during varying intensities of fixed perceived effort cycling: A mixed method study

Using a think aloud approach during fixed perceived effort exercise is a unique method to explore the decision-making processes that guide the self-regulation of perceived effort during endurance-based activity. In a two-part study, authors investigated the attentional focus and self-regulatory strategies associated with: Part A - perceived effort corresponding to (RPEGET) and above gas exchange threshold (RPE+15%GET); Part B - between experienced and inexperienced cyclists during fixed perceived effort cycling tasks. Eighteen (15 male, 3 female) healthy, active individuals completed three visits (visit 1 - ramped incremental test and familiarisation, visit 2 and 3-30-min fixed perceived effort cycling). During which, power output, heart rate, lactate, think aloud, and perceptual markers were taken. Random-intercepts linear mixed-effects models assessed the condition, time, and condition × time interactions on all dependent variables. Power output, heart rate, lactate and instances of internal sensory monitoring (t195=2.57,p=.011,β=0.95[0.23,1.68]) and self-regulation (t195=4.14,p=.001,β=1.69[0.89,2.49]) were significantly higher in the RPE+15%GET versus RPEGET trial. No significant differences between inexperienced and experienced cyclists for internal sensory monitoring (t196=-1.78,p=.095,β=-1.73[-3.64,0.18]) or self-regulatory thoughts (t196=-0.39,p=.699,β=-1.06[-6.32,4.21]) were noted but there were significant condition × time interactions for internal monitoring (t196=2.02,p=.045,β=0.44[0.01,0.87]) and self-regulation (t196=3.45,p=.001,β=0.85[0.37,1.33]). Seemingly, experienced athletes associatively attended to internal psychophysiological state and subsequently self-regulate their psychophysiological state at earlier stages of exercise than inexperienced athletes. This is the first study to exhibit the differences in attentional focus and self-regulatory strategies that are activated based on perceived effort intensity and experience level in cyclists.

The effect of incentivization on the conjunction fallacy in judgments: a meta-analysis

The conjunction fallacy is a classical judgment bias that was argued to be a robust cognitive illusion insensitive to the positive effect of incentivization. We conducted a meta-analysis of the literature (n = 3276) and found that although most studies did not report a significant effect of incentivization, the results across studies show a significant positive effect for incentivization, d = 0.19, with an odds ratio of 1.40 for answering correctly when incentivized. There was no moderating effect of payoff size despite the differences in incentive value between studies. Additionally, the effect was relatively smaller when examining absolute differences in the probability of correct judgment instead of odds ratios, suggesting that it may be partly driven by studies with low baseline performance. These findings join those of other judgment-bias studies to suggest a small but nevertheless robust debiasing effect of incentivization.

Can personal task choice shield against fear and anger prime effects on effort? A study on cardiac response

This experiment tested whether personal task choice can shield against implicit affective influences on sympathetically mediated cardiovascular response, reflecting effort. Participants were N = 121 healthy university students who completed a moderately difficult memory task with integrated briefly flashed and masked fear vs. anger primes. Half of the participants believed they could choose between an attention and a memory task, while the other half was automatically assigned to the task. Replicating previous research, we expected an influence of the affect primes on effort when the task was externally assigned. By contrast, when participants were given a task choice, we predicted strong action shielding and thus a weak implicit affect effect on resource mobilization. As expected, participants in the assigned task condition showed stronger cardiac pre-ejection period reactivity when exposed to fear primes than when processing anger primes. Importantly, this affect prime effect disappeared when participants could ostensibly choose the task. These findings add to other recent evidence for action shielding by personal task choice and importantly extend this effect to implicit affective influences on cardiac reactivity during task performance.

The pre-ejection period is a highly stress dependent parameter of paramount importance for pulse-wave-velocity based applications

Purpose

The pulse-wave-velocity, is used for indirect, cuff-less, continuous blood pressure estimation. It is commonly detected by measuring the time delay between a defined point in an ECG and the arrival of the peripheral pulse wave (e.g., oxygen saturation sensor). The period between electrical stimulation of the heart (ECG) and actual blood ejection from the heart is called the pre-ejection period (PEP). This study aims at characterizing the PEP under mental and physical stress with focus on its relations to other cardiovascular parameters such as heart rate and importance for blood pressure (BP) estimation.

Methods

We measured the PEP in 71 young adults at rest, under mental (TSST) and physical stress (ergometer) via impedance-cardiography.

Results

The PEP is highly dependent on mental and physical load. It is strongly correlated with indicators of sympathetic strain (p < 0.001). At rest (mean 104.5 ms), the PEP shows a high interindividual variability but small intraindividual variability. Mental stress decreases the PEP by 16% (mean 90.0 ms) while physical stress halves PEP (mean 53.9 ms). The PEP does correlate differently with heart rate under differing circumstances (rest: R ² 0.06, mental stress: R ² 0.29, physical stress: R ² 0.65). Subsequently, using PEP and heart rate enables the discrimination of rest, mental and physical strain with a positive predictive value of 93%.

Conclusion

The PEP is a cardiovascular parameter with large interindividual variability at rest and subject-depended dynamic under load which is of great importance for ECG-based pulse-wave-velocity (PWV) determination. Considering its variability and large impact on the pulse arrival time, PEP is a crucial factor in PWV based BP estimation.

Mental contrasting and energization transfer to low-expectancy tasks

Mentally contrasting future with reality is a self-regulation strategy that triggers expectancy-dependent energization for tasks instrumental to attaining the desired future. Energization by mental contrasting even transfers to tasks unrelated to the desired future at hand. Would such energization transfer by mental contrasting even energize people to perform unrelated tasks for which they have low success expectations? In Laboratory Experiment 1, mentally contrasting (vs. indulging) about performing well in a creativity task triggered physiological energization and better performance in an unrelated low-expectancy cognitive task that participants received in place of the creativity task. In Field Experiment 2, mentally contrasting an interpersonal wish helped schoolchildren invest more effort and perform better in a low-expectancy academic task—finding typos. Online Experiment 3 replicated Experiment 2 with adults. Mental contrasting participants’ effort and performance in the low-expectancy academic task did not differ from their effort and performance in a high-expectancy task. We discuss implications for designing interventions to foster energization for low-expectancy tasks.

Virtual Reality Adaptation Using Electrodermal Activity to Support the User Experience

Virtual reality is increasingly used for tasks such as work and education. Thus, rendering scenarios that do not interfere with such goals and deplete user experience are becoming progressively more relevant. We present a physiologically adaptive system that optimizes the virtual environment based on physiological arousal, i.e., electrodermal activity. We investigated the usability of the adaptive system in a simulated social virtual reality scenario. Participants completed an n-back task (primary) and a visual detection (secondary) task. Here, we adapted the visual complexity of the secondary task in the form of the number of non-player characters of the secondary task to accomplish the primary task. We show that an adaptive virtual reality can improve users’ comfort by adapting to physiological arousal regarding the task complexity. Our findings suggest that physiologically adaptive virtual reality systems can improve users’ experience in a wide range of scenarios.

Pulse arrival time as a surrogate of blood pressure

Various models have been proposed for the estimation of blood pressure (BP) from pulse transit time (PTT). PTT is defined as the time delay of the pressure wave, produced by left ventricular contraction, measured between a proximal and a distal site along the arterial tree. Most researchers, when they measure the time difference between the peak of the R-wave in the electrocardiogram signal (corresponding to left ventricular depolarisation) and a fiducial point in the photoplethysmogram waveform (as measured by a pulse oximeter attached to the fingertip), describe this erroneously as the PTT. In fact, this is the pulse arrival time (PAT), which includes not only PTT, but also the time delay between the electrical depolarisation of the heart's left ventricle and the opening of the aortic valve, known as pre-ejection period (PEP). PEP has been suggested to present a significant limitation to BP estimation using PAT. This work investigates the impact of PEP on PAT, leading to a discussion on the best models for BP estimation using PAT or PTT. We conducted a clinical study involving 30 healthy volunteers (53.3% female, 30.9 ± 9.35 years old, with a body mass index of 22.7 ± 3.2 kg/m[Formula: see text]). Each session lasted on average 27.9 ± 0.6 min and BP was varied by an infusion of phenylephrine (a medication that causes venous and arterial vasoconstriction). We introduced new processing steps for the analysis of PAT and PEP signals. Various population-based models (Poon, Gesche and Fung) and a posteriori models (inverse linear, inverse squared and logarithm) for estimation of BP from PTT or PAT were evaluated. Across the cohort, PEP was found to increase by 5.5 ms ± 4.5 ms from its baseline value. Variations in PTT were significantly larger in amplitude, - 16.8 ms ± 7.5 ms. We suggest, therefore, that for infusions of phenylephrine, the contribution of PEP on PAT can be neglected. All population-based models produced large BP estimation errors, suggesting that they are insufficient for modelling the complex pathways relating changes in PTT or PAT to changes in BP. Although PAT is inversely correlated with systolic blood pressure (SBP), the gradient of this relationship varies significantly from individual to individual, from - 2946 to - 470.64 mmHg/s in our dataset. For the a posteriori inverse squared model, the root mean squared errors (RMSE) for systolic and diastolic blood pressure (DBP) estimation from PAT were 5.49 mmHg and 3.82 mmHg, respectively. The RMSEs for SBP and DBP estimation by PTT were 4.51 mmHg and 3.53 mmHg, respectively. These models take into account individual calibration curves required for accurate blood pressure estimation. The best performing population-based model (Poon) reported error values around double that of the a posteriori inverse squared model, and so the use of population-based models is not justified.

Explicit achievement motive strength determines effort-related myocardial beta-adrenergic activity if task difficulty is unclear but not if task difficulty is clear

Work on physiological and other behavioral correlates of motives often assumes that motives exert a direct effect on behavior once activated. Motivational intensity theory, however, suggests that this does not always apply. In the context of task engagement, motive strength should exert a direct effect on myocardial beta-adrenergic activity if task difficulty is unclear, but not if task difficulty is known. The presented study tested this prediction for the impact of the explicit achievement motive on myocardial beta-adrenergic activity-assessed as pre-ejection period (PEP) reactivity during task performance. Seventy-eight participants performed one of two versions of a mental arithmetic task. After having completed the achievement motive scale of the Personality Research Form, participants were either informed about the difficulty of the task or not before working on it. Participants' PEP reactivity during task performance provided evidence for the predicted moderating impact of clarity of task difficulty: PEP reactivity increased with increasing achievement motive strength if task difficulty was unclear, but not if it was clear. These findings demonstrate that the explicit achievement motive impact on myocardial beta-adrenergic activity is moderated by clarity of task difficulty and suggest that motive strength does not always translate into direct effects on physiology and behavior.

Sympathetic involvement in time-constrained sequential foraging

Appraising sequential offers relative to an unknown future opportunity and a time cost requires an optimization policy that draws on a learned estimate of an environment’s richness. Converging evidence points to a learning asymmetry, whereby estimates of this richness update with a bias toward integrating positive information. We replicate this bias in a sequential foraging (prey selection) task and probe associated activation within the sympathetic branch of the autonomic system, using trial-by-trial measures of simultaneously recorded cardiac autonomic physiology. We reveal a unique adaptive role for the sympathetic branch in learning. It was specifically associated with adaptation to a deteriorating environment: it correlated with both the rate of negative information integration in belief estimates and downward changes in moment-to-moment environmental richness, and was predictive of optimal performance on the task. The findings are consistent with a framework whereby autonomic function supports the learning demands of prey selection.

Social observation increases the cardiovascular response of hearing-impaired listeners during a speech reception task

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.

Effects of Transcranial Direct Current Stimulation on effort during a working-memory task

Transcranial Direct Current Stimulation (tDCS) has shown that stimulation of Dorsolateral Prefrontal Cortex (DLPFC) facilitates task performance in working-memory tasks. However, little is known about its potential effects on effort. This study examined whether tDCS affects effort during a working-memory task. Participants received anodal, cathodal and sham stimulation over DLPFC across three sessions before carrying out a 2-back task. During the task, effort-related cardiovascular measures were recorded-especially the Initial Systolic Time Interval (ISTI). Results showed that anodal stimulation produced a shorter ISTI, indicating a greater effort compared to cathodal and sham conditions, where effort was lower. These findings demonstrate that anodal stimulation helps participants to maintain engagement in a highly demanding task (by increasing task mastery), without which they would otherwise disengage. This study is the first to show that tDCS impacts the extent of effort engaged by individuals during a difficult task.

The Intensity Side of Volition

Abstract. Attaining sports or health goals requires not only high motivation but also the willpower to translate sport-behavior intentions into successful action. This volitional regulation calls for the mobilization of effort to overcome obstacles in the pursuit of goals. The present article provides a theoretical and empirical overview of motivation intensity theory ( Brehm & Self, 1989 ) – a conceptual framework that makes clear and testable predictions about effort mobilization in various contexts. First, we present the guiding principles of this theory and its operationalizations by measures of effort-related cardiovascular reactivity and physical handgrip force. Second, we review a selection of empirical tests of the basic assumptions of this theory and the impact of psychological moderator variables such as affect, fatigue, pain, and personality on effort mobilization. Finally, we discuss important implications of these findings for the sports and health domains and make suggestions for future research.

Onset of substance use: Deviant peer, sex, and sympathetic nervous system predictors

We evaluated whether the association between deviant peer affiliation and onset of substance use is conditional upon sex and sympathetic nervous system (SNS) reactivity as measured by pre-ejection period (PEP). Community-sampled adolescents (N = 251; M = 15.78 years; 53% female; 66% White, 34% Black) participated in three waves. PEP reactivity was collected during a mirror star-tracer stress task. Alcohol, marijuana, tobacco, or any substance use, as well as binge drinking and sexual activity involving substance use were outcomes predicted by affiliation with deviant peers and two- and three-way interactions with sex and PEP reactivity. Probability of substance use increased over time, but this was amplified for adolescents with greater deviant peer affiliation in conjunction with blunted PEP reactivity. The same pattern of results was also found for prediction of binge drinking and sexual activity involving substance use. Findings are discussed in the context of biosocial models of adolescent substance use and health risk behaviors.

RZ Interval as an Impedance Cardiography Indicator of Effort-Related Cardiac Sympathetic Activity

Research on effort and motivation commonly assesses how the sympathetic branch of the autonomic nervous system affects the cardiovascular system. The cardiac pre-ejection period (PEP), assessed via impedance cardiography, is a common outcome, but assessing PEP requires identifying subtle points on cardiac waveforms. The present research examined the psychometric value of the RZ interval (RZ), which has recently been proposed as an indicator of sympathetic activity, for effort research. Also known as the initial systolic time interval (ISTI), RZ is the time (in ms) between the ECG R peak and the dZ/dt Z peak. Unlike PEP, RZ involves salient waveform points that are easily and reliably identified. Data from two experiments evaluated the suitability of RZ for effort paradigms and compared it to a popular automated PEP method. In Studies 1 (n = 89) and 2 (n = 71), participants completed a standard appetitive task in which each correct response earned a small amount of cash. As expected, incentives significantly affected PEP and RZ in both experiments. PEP and RZ were highly correlated (all rs ≥ 0.89), and RZ consistently yielded a larger effect size than PEP. In Study 3, a quantitative synthesis of the experiments indicated that the effect size of RZ's response to incentives (Hedges's g = 0.432 [0.310, 0.554]) was roughly 15% larger than PEP's effect size (g = 0.376 [0.256, 0.496]). RZ thus appears promising for future research on sympathetic aspects of effort-related cardiac activity.

Ventromedial Prefrontal Cortex Activity and Sympathetic Allostasis During Value-Based Ambivalence

Anxiety is characterized by low confidence in daily decisions, coupled with high levels of phenomenological stress. Ventromedial prefrontal cortex (vmPFC) plays an integral role in maladaptive anxious behaviors via decreased sensitivity to threatening vs. non-threatening stimuli (fear generalization). vmPFC is also a key node in approach-avoidance decision making requiring two-dimensional integration of rewards and costs. More recently, vmPFC has been implicated as a key cortical input to the sympathetic branch of the autonomic nervous system. However, little is known about the role of this brain region in mediating rapid stress responses elicited by changes in confidence during decision making. We used an approach-avoidance task to examine the relationship between sympathetically mediated cardiac stress responses, vmPFC activity and choice behavior over long and short time-scales. To do this, we collected concurrent fMRI, EKG and impedance cardiography recordings of sympathetic drive while participants made approach-avoidance decisions about monetary rewards paired with painful electric shock stimuli. We observe first that increased sympathetic drive (shorter pre-ejection period) in states lasting minutes are associated with choices involving reduced decision ambivalence. Thus, on this slow time scale, sympathetic drive serves as a proxy for "mobilization" whereby participants are more likely to show consistent value-action mapping. In parallel, imaging analyses reveal that on shorter time scales (estimated with a trial-to-trial GLM), increased vmPFC activity, particularly during low-ambivalence decisions, is associated with decreased sympathetic state. Our findings support a role of sympathetic drive in resolving decision ambivalence across long time horizons and suggest a potential role of vmPFC in modulating this response on a moment-to-moment basis.

Maturation of the Cardiac Autonomic Nervous System Activity in Children and Adolescents

Background

Despite the increasing interest in cardiac autonomic nervous activity, the normal development is not fully understood. The main aim was to determine the maturation of different cardiac sympathetic‐(SNS) and parasympathetic nervous system (PNS) activity parameters in healthy patients aged 0.5 to 20 years. A second aim was to determine potential sex differences.

Methods and Results

Five studies covering the 0.5‐ to 20‐year age range provided impedance‐ and electrocardiography recordings from which heart rate, different PNS‐parameters (eg, respiratory sinus arrhythmia) and an SNS‐parameter (pre‐ejection period) were collected. Age trends were computed in the mean values across 12 age‐bins and in the age‐specific variances. Age was associated with changes in mean and variance of all parameters. PNS‐activity followed a cubic trend, with an exponential increase from infancy, a plateau phase during middle childhood, followed by a decrease to adolescence. SNS‐activity showed a more linear trend, with a gradual decrease from infancy to adolescence. Boys had higher SNS‐activity at ages 11 to 15 years, while PNS‐activity was higher at 5 and 11 to 12 years with the plateau level reached earlier in girls. Interindividual variation was high at all ages. Variance was reasonably stable for SNS‐ and the log‐transformed PNS‐parameters.

Conclusions

Cardiac PNS‐ and SNS‐activity in childhood follows different maturational trajectories. Whereas PNS‐activity shows a cubic trend with a plateau phase during middle childhood, SNS‐activity shows a linear decrease from 0.5 to 20 years. Despite the large samples used, clinical use of the sex‐specific centile and percentile normative values is modest in view of the large individual differences, even within narrow age bands.

Perceptual and Physiological Responses to Carbohydrate and Menthol Mouth-Swilling Solutions: A Repeated Measures Cross-Over Preliminary Trial

Carbohydrate and menthol mouth-swilling have been used to enhance exercise performance in the heat. However, these strategies differ in mechanism and subjective experience. Participants (n = 12) sat for 60 min in hot conditions (35 °C; 15 ± 2%) following a 15 min control period, during which the participants undertook three 15 min testing blocks. A randomised swill (carbohydrate; menthol; water) was administered per testing block (one swill every three minutes within each block). Heart rate, tympanic temperature, thermal comfort, thermal sensation and thirst were recorded every three minutes. Data were analysed by ANOVA, with carbohydrate intake controlled for via ANCOVA. Small elevations in heart rate were observed after carbohydrate (ES: 0.22 ± 90% CI: −0.09–0.52) and water swilling (0.26; −0.04–0.54). Menthol showed small improvements in thermal comfort relative to carbohydrate (−0.33; −0.63–0.03) and water (−0.40; from −0.70 to −0.10), and induced moderate reductions in thermal sensation (−0.71; from −1.01 to −0.40 and −0.66; from −0.97 to −0.35, respectively). Menthol reduced thirst by a small to moderate extent. These effects persisted when controlling for dietary carbohydrate intake. Carbohydrate and water may elevate heart rate, whereas menthol elicits small improvements in thermal comfort, moderately improves thermal sensation and may mitigate thirst; these effects persist when dietary carbohydrate intake is controlled for.

Investigating the Influences of Task Demand and Reward on Cardiac Pre-Ejection Period Reactivity During a Speech-in-Noise Task

OBJECTIVES

Effort investment during listening varies as a function of task demand and motivation. Several studies have manipulated both these factors to elicit and measure changes in effort associated with listening. The cardiac pre-ejection period (PEP) is a relatively novel measure in the field of cognitive hearing science. This measure, which reflects sympathetic nervous system activity on the heart, has previously been implemented during a tone discrimination task but not during a speech-in-noise task. Therefore, the primary goal of this study was to explore the influences of signal to noise ratio (SNR) and monetary reward level on PEP reactivity during a speech-in-noise task.

DESIGN

Thirty-two participants with normal hearing (mean age = 22.22 years, SD = 3.03) were recruited at VU University Medical Center. Participants completed a Dutch speech-in-noise test with a single-interfering-talker masking noise. Six fixed SNRs, selected to span the entire psychometric performance curve, were presented in a block-wise fashion. Participants could earn a low (€0.20) or high (€5.00) reward by obtaining a score of ≥70% of words correct in each block. The authors analyzed PEP reactivity: the change in PEP measured during the task, relative to the baseline during rest. Two separate methods of PEP analysis were used, one including data from the whole task block and the other including data obtained during presentation of the target sentences only. After each block, participants rated their effort investment, performance, tendency to give up, and the perceived difficulty of the task. They also completed the need for recovery questionnaire and the reading span test, which are indices of additional factors (fatigue and working memory capacity, respectively) that are known to influence listening effort.

RESULTS

Average sentence perception scores ranged from 2.73 to 91.62%, revealing a significant effect of SNR. In addition, an improvement in performance was elicited by the high, compared to the low reward level. A linear relationship between SNR and PEP reactivity was demonstrated: at the lower SNRs PEP reactivity was the most negative, indicating greater effort investment compared to the higher SNRs. The target stimuli method of PEP analysis was more sensitive to this effect than the block-wise method. Contrary to expectations, no significant impact of reward on PEP reactivity was found in the present dataset. Also, there was no physiological evidence that participants were disengaged, even when performance was poor. A significant correlation between need for recovery scores and average PEP reactivity was demonstrated, indicating that a lower need for recovery was associated with less effort investment.

CONCLUSIONS

This study successfully implemented the measurement of PEP during a standard speech-in-noise test and included two distinct methods of PEP analysis. The results revealed for the first time that PEP reactivity varies linearly with task demand during a speech-in-noise task, although the effect size was small. No effect of reward on PEP was demonstrated. Finally, participants with a higher need for recovery score invested more effort, as shown by average PEP reactivity, than those with a lower need for recovery score.

Influence of common lighting conditions and time-of-day on the effort-related cardiac response

Melanopic stimuli trigger diverse non-image-forming effects. However, evidence of a melanopic contribution to acute effects on alertness and performance is inconclusive, especially under common lighting situations. Effects on cognitive performance are likely mediated by effort-related physiological changes. We assessed the acute effects of lighting in three scenarios, at two times of day, on effort-related changes to cardiac contraction as indexed by the cardiac pre-ejection period (PEP). In a within-subject design, twenty-seven participants performed a cognitive task thrice during a morning and a late-afternoon session. We set the lighting at 500 lux in all three lighting scenarios, measured horizontally at the desk level, but with 54 lux, 128 lux, or 241 lux melanopic equivalent daylight illuminance at the eye level. Impedance cardiography and electrocardiography measurements were used to calculate PEP, for the baseline and task period. A shorter PEP during the task represents a sympathetic heart activation and therefore increased effort. Data were analysed with linear mixed-effect models. PEP changes depended on both the light scene and time of day (p = 0.01 and p = 0.002, respectively). The highest change (sympathetic activation) occurred for the medium one of the three stimuli (128 lux) during the late-afternoon session. However, effect sizes for the singular effects were small, and only for the combined effect of light and time of day middle-sized. Performance scores or self-reported scores on alertness and task demand did not change with the light scene. In conclusion, participants reached the same performance most efficiently at both the highest and lowest melanopic setting, and during the morning session. The resulting U-shaped relation between melanopic stimulus intensity and PEP is likely not dependent solely on intrinsic ipRGC stimuli, and might be moderated by extrinsic cone input. Since lighting situations were modelled according to current integrative lighting strategies and real-life indoor light intensities, the result has implications for artificial lighting in a work environment.

Sympathetic arousal during the processing of dysphoric affect by youths at high and low familial risk for depression

Youths at high risk for depression have been shown to have problems in repairing their own sad mood. Given that sympathetic arousal has been implicated both in the experience and regulation of affect, an atypical pattern of arousal may be one of the factors that contribute to mood repair problems. In the current study, we measured sympathetic arousal of never-depressed youths at high (n = 56) and low (n = 67) familial risk for depression during sad mood induction and instructed mood repair. Sympathetic arousal was indexed by skin conductance level (SCL) and cardiac pre-ejection period (PEP); mood repair outcome was indexed by self-rated affect. High-risk youths demonstrated increased SCL during sadness induction, which persisted during mood repair; low-risk youths evidenced increased SCL only during mood repair. Shortened PEP was evident only among high-risk youths and only during mood repair. Furthermore, shortened PEP during mood induction predicted less successful mood repair in the low-risk but not in the high-risk group. The findings suggest that: (a) depression-prone youths differ from control peers in patterns of sympathetic responses to emotional stimuli, which may impair their ability to relieve sadness, and (b) activation patterns differ across subsystems (SCL vs. PEP) of sympathetic activity, in conjunction with depression risk status.

Response Inhibition, Response Execution, and Emotion Regulation among Children with Attention-Deficit/Hyperactivity Disorder

Attention-deficit/hyperactivity disorder (ADHD) is associated with deficits in response inhibition, response execution, and emotion regulation. However, the nature of the associations among these deficits remains unclear. Thus, this study examines these associations using a multi-method design. One hundred sixty-six children (aged 5-13 years; 66.3% male; 75 with ADHD) completed two conditions (i.e., neutral and fear) of an emotional go/no-go task. Parasympathetic-based regulation was indexed via respiratory sinus arrhythmia (RSA), and sympathetic-based reactivity was indexed via cardiac pre-ejection period (PEP). Overall, children exhibited more difficulty with response execution (i.e., more omission errors, fewer correct go responses) and less difficulty with response inhibition (i.e., fewer commission errors, more correct no-go responses) during the fear condition than the neutral condition. Children with ADHD displayed more difficulty with response execution during the fear condition compared to typically developing youth. Additionally, children with ADHD displayed parasympathetic-based dysregulation (i.e., RSA increase from baseline) and reduced sympathetic-based reactivity (i.e., PEP lengthening) compared to typically developing youth across task conditions. In sum, children with ADHD demonstrate greater difficulty with response execution during emotionally salient contexts, as well as parasympathetic-based emotion dysregulation. Future work should examine these associations longitudinally with the aim of predicting impairment and treatment response in youth with ADHD.

Mortality salience, effort, and cardiovascular response to a bar-press challenge: Remarkably nuanced effects of a death prime on heart performance

We presented participants with a bar-pressing challenge relevant to their identity after having exposed them to a prime that made their mortality more or less salient. For some participants, difficulty was low; for others, it was high; for the rest, it was unfixed. As expected, heart pre-ejection period responses-reflecting heart contraction force-were (a) stronger under high-salience conditions when difficulty was high and unfixed, but (b) low regardless of salience when difficulty was low. Findings bear out conceptually and extend results from a previous experiment. In doing so, they add substantively to a new line of support for terror management theory and document the predictive utility of a proposed blended analysis of associated effort processes. The blended analysis speaks to the way in which motives to manage existential terror should convert into active goal striving and to the impact that existential threat might have on aspects of autonomic arousal.

Cross system autonomic balance and regulation: Associations with depression and anxiety symptoms

The autonomic nervous system (ANS) has demonstrated utility for identifying alterations in emotion processing associated with common psychopathology, including depression and anxiety. To date though the majority of this ANS research has several limitations. Most studies have examined parasympathetic and sympathetic branches separately, requiring activity in the other branch be inferred. This is problematic as each branch may function independently. Composite indices such as cardiac autonomic balance (CAB) and cardiac autonomic regulation (CAR) which examine the relative input between respiratory sinus arrhythmia (RSA) and pre-ejection period (PEP) should provide more comprehensive measures of autonomic functioning and thus stronger predictors of psychopathology. However, the sympathetic branch is driven by multiple neurotransmitter systems, thus PEP does not necessarily reflect overall SNS arousal. We propose two new metrics for assessing ANS functioning associated with psychopathology: parasympathetic effects on cardiac control (RSA) relative to sympathetic effects on the eccrine system (electrodermal activity, EDA), which we term cross-system autonomic balance (CSAB) and regulation (CSAR). Eighty-five women (18-37) completed a baseline physiological assessment with parasympathetic (RSA) and sympathetic indices (PEP, EDA), along with self-reported depressive and anxiety symptoms. Lower CSAB, indicating sympathetic dominance driven by cholinergic neurotransmission, was associated with higher depressive and anxiety symptoms. Lower CAB indicating sympathetic dominance driven by beta-adrenergic neurotransmission was associated specifically with depressive symptoms. CSAB was a more robust index than RSA. Results support the utility of assessing multiple composite ANS indices for identifying physiological substrates of alterations in emotion regulation associated with internalizing disorders.

Harsh parenting and youth systemic inflammation: Modulation by the autonomic nervous system

OBJECTIVE

The present study aimed to test the role of the autonomic nervous system (ANS) in modulating the impact of family stress induced by harsh parenting on youths' inflammation. First, we examined the direct effect of severity of adverse parenting behaviors on two serum biomarkers of systemic inflammation (C-reactive protein and interleukin-6) among youth. Second, we tested the moderating role of ANS reactivity in response to laboratory-induced stress in the association between harsh parenting and inflammation among these youth.

METHOD

The sample included 101 low-income children (75.2% African American) between 9 and 12 years of age (M_age = 10.9; SD_age = 1.2) who participated in a conflict task with their primary caregiver in a laboratory setting. Heart rate variability reactivity (HRV-R), skin conductance level reactivity (SCL-R), and preejection period reactivity (PEPr-R) were used to index parasympathetic and sympathetic nervous system reactivity. Markers of low-grade inflammation (C-reactive protein and interleukin-6) were obtained from serum.

RESULTS

After adjusting for confounding variables, ANS activity moderated the associations between family stress and systemic inflammation. Specifically, elevated HRV-R buffered the effect of family stress on youths' inflammation, whereas elevated PEPr-R and SCL-R exacerbated the effect.

CONCLUSION

These findings show that self-regulatory capacity and threat sensitivity, as indicated by ANS function, may have an impact on the associations between family stress and systemic inflammation. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Investigating Flow State and Cardiac Pre-ejection Period During Electronic Gaming Machine Use

Flow activities (e.g. sports and gaming) have been associated with positive affect and prolonged engagement. In the gambling field, modern electronic gaming machines (EGMs, including modern slot machines) have drawn concern as a potentially flow-inducing activity that may be associated with gambling-related harms. Current research has heavily relied on self-reported flow, and further insights may be afforded by physiological methods. We present data from three separate experiments in which self-reported gambling flow and cardiac pre-ejection period (PEP; a measure of sympathetic nervous system arousal) were examined. Male undergraduate participants gambled on a genuine EGM in a laboratory setting for a period of at least 15 min, and completed the Flow subscale of the game experience questionnaire (GEQ). Aggregated data were analyzed using multilevel regression. Although EGM gambling was not associated with significant changes in PEP across participants, we found that self-reported flow states were associated with significant decreases in PEP during the first five minutes of EGM use. Thus, participants who experienced flow showed a greater sympathetic nervous system response to the onset of gambling. Though these effects were consistent in experiments 1 and 2, in experiment 3 the effect was inverted during the same time window. We conclude that flow during EGM gambling appears to be associated with early changes in sympathetic nervous system activity, but stress that more research is needed to characterize boundary conditions and moderating factors.

Child Maltreatment, Autonomic Nervous System Responsivity, and Psychopathology: Current State of the Literature and Future Directions

Child maltreatment may affect autonomic nervous system (ANS) responsivity, and ANS responsivity may influence the impact of child maltreatment on later outcomes including long-term mental/physical health. This review systematically evaluated the evidence regarding effects of maltreatment on ANS responsivity in children and examined how ANS responsivity may influence the association between maltreatment and psychopathology, with attention to relevant developmental issues. We searched the literature for relevant studies using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched five electronic databases, performed key word searches in relevant journals, hand searched reference sections of relevant articles, and contacted experts in the field. Articles were extracted according to inclusion criteria and their quality assessed. The search produced 1,388 articles; 22 met inclusion criteria. Most of the studies suggested blunted cardiovascular responsivity generally and sympathetic activation specifically in response to stress in maltreated children compared to nonmaltreated children. Findings around vagal responsivity and skin conductance were mixed. Limited evidence was found for ANS responsivity as a moderator or mediator of psychopathology risk among maltreated children. Maltreatment may be associated with blunted sympathetic activation in stressful situations. Differences in ANS responsivity may influence psychopathology risk among maltreated children. Further research is needed to confirm the nature and magnitude of such effects.

Listening effort: Are we measuring cognition or affect, or both?

Listening effort is increasingly recognized as a factor in communication, particularly for and with nonnative speakers, for the elderly, for individuals with hearing impairment and/or for those working in noise. However, as highlighted by McGarrigle et al., International Journal of Audiology, 2014, 53, 433-445, the term "listening effort" encompasses a wide variety of concepts, including the engagement and control of multiple possibly distinct neural systems for information processing, and the affective response to the expenditure of those resources in a given context. Thus, experimental or clinical methods intended to objectively quantify listening effort may ultimately reflect a complex interaction between the operations of one or more of those information processing systems, and/or the affective and motivational response to the demand on those systems. Here we examine theoretical, behavioral, and psychophysiological factors related to resolving the question of what we are measuring, and why, when we measure "listening effort." This article is categorized under: Linguistics > Language in Mind and Brain Psychology > Theory and Methods Psychology > Attention Psychology > Emotion and Motivation.

Affect and cognitive control: Insights from research on effort mobilization

We present theory and research on effort mobilization that is relevant for understanding the role of affect in cognitive control. We posit that cognitive control and effort are closely related and introduce motivational intensity theory and supporting empirical evidence mainly based on cardiovascular measures of effort. Most important, we discuss the role of affect in the context of effort mobilization and cognitive control from different perspectives. We first present theories predicting affective influences on effort, namely the mood-behavior-model and the implicit-affect-primes-effort model, and supporting empirical evidence. Second, we discuss further implications of the resource conservation principle highlighting the aversive aspect of effort and review evidence for the impact of value and its affective component on effort and cognitive control. Finally, we present a recent integration of the neural mechanisms underlying both effort and cognitive control. We conclude that affective processes are necessary and instrumental for both effort mobilization and cognitive control.

Sleep deprivation, effort allocation and performance

Sleep deprivation causes physiological alterations (e.g., decreased arousal, intrusion of micro-sleeps), that negatively affect performance on a wide range of cognitive domains. These effects indicate that cognitive performance relies on a capacity-limited system that may be more challenged in the absence of sleep. Additionally, sleep loss can result in a lower willingness to exert effort in the pursuit of performance goals. Such deficits in motivation may interact with the effects of capacity limitations to further stifle cognitive performance. When sleep-deprived, cognitive performance is experienced as more effortful, and intrinsic motivation to perform dwindles. On the other hand, increasing motivation extrinsically (e.g., by monetary incentives) can inspire individuals to allocate more task-related effort, and can partially counter performance deficits associated with sleep deprivation. In this chapter, we review current research on the interplay between sleep deprivation, effort and performance. We integrate these findings into an effort-based decision-making framework in which sleep-related performance impairments may result from a voluntary decision to withdraw effort. We conclude with practical implications of this framework for performance in healthy populations (e.g., work productivity) and clinical conditions.

Major depression impairs incentive processing: evidence from the heart and the face

BACKGROUND

The present study tested the hypothesis of a differential pattern of reward and punishment responsiveness in depression measuring effort mobilization during anticipation and facial expressions during consumption.

METHODS

Twenty patients with major depressive disorder (MDD) and 20 control participants worked on a memory task under neutral, reward, and punishment instructions. Effort mobilization was operationalized as cardiovascular reactivity, while facial expressions were measured by facial electromyographic reactivity. Self-report measures for each phase complemented this multi-method approach.

RESULTS

During anticipation, MDD patients showed weaker cardiac pre-ejection period (PEP) reactivity to reward and blunted self-reported wanting, but weaker PEP reactivity to punishment and unchanged self-reported avoidance motivation. During consumption, MDD patients showed reduced zygomaticus major muscle reactivity to reward and blunted self-reported liking, but unchanged corrugator supercilii muscle reactivity to punishment and unchanged self-reported disliking.

CONCLUSIONS

These findings demonstrate reduced effort mobilization during reward and punishment anticipation in depression. Moreover, they show reduced facial expressions during reward consumption and unchanged facial expressions during punishment consumption in depression.

Parent Emotion Expression and Autonomic-Linked Emotion Dysregulation in Childhood ADHD

Despite evidence that ADHD is associated with disruptions in emotion regulation, few studies have examined the biological correlates of emotion dysregulation among children with this disorder. Prior work has pointed to roles of the parasympathetic and sympathetic nervous system, as indexed via respiratory sinus arrhythmia (RSA) and cardiac pre-ejection period (PEP), respectively. Work in typically developing populations suggests that parenting behavior and parental emotion expression may shape the development of these systems. To date, a single study has examined the independent and interactive roles of autonomic nervous system functioning and parent emotion expression in youth with ADHD. This study seeks to extend that work. 86 children (42 with ADHD), aged 8-12 years, and a parent completed a parent-child interaction task, while electrocardiography and impedance cardiography data were recorded to derive RSA and PEP. Parent and child emotion word use (positive and negative valence) were coded from recordings of the task. Parents of youth with ADHD used fewer positive emotion words throughout the task. Additionally, throughout the task, children with ADHD engaged in excessive RSA withdrawal from baseline. Further, the association between RSA reactivity and ADHD diagnosis was moderated by parent positive emotion word use. Specifically, those with RSA augmentation and parents displaying high positive affect across the task conditions were least likely to have an ADHD diagnosis. If replicated and extended, these results support the use of interventions specifically designed to increase parental modeling of positive emotions, while simultaneously focusing on building emotion regulation skills in youth with ADHD.

Conscientiousness and Effort-Related Cardiac Activity in Response to Piece-Rate Cash Incentives

Although conscientiousness predicts many aspects of motivation, from delay of gratification to higher achievement, its relationship to responses to monetary incentives is surprisingly inconsistent. Several studies have found null or relationships between conscientiousness and behavioral performance in piece-rate, pay-for-performance tasks, in which people earn money for each unit of work completed. In the present study, we examined the role of conscientiousness in effort-related cardiac activity and behavioral performance during a pay-for-performance task. People worked on a self-paced, piece-rate cognitive task in which they earned 1 cent or 5 cents, manipulated within-person, for each correct response. Conscientiousness predicted greater physiological effort (i.e., shorter pre-ejection period [PEP] reactivity) as incentives increased but had no effect on behavioral performance. The findings suggest that conscientiousness is significantly related to effort for piece-rate tasks, and they reinforce a core idea in motivational intensity theory: effort, performance, and persistence are distinct outcomes that often diverge, so drawing conclusions about effort from performance can be complex.

The Emotion Process: Event Appraisal and Component Differentiation

Much emotion research has focused on the end result of the emotion process, categorical emotions, as reported by the protagonist or diagnosed by the researcher, with the aim of differentiating these discrete states. In contrast, this review concentrates on the emotion process itself by examining how ( a) elicitation, or the appraisal of events, leads to ( b) differentiation, in particular, action tendencies accompanied by physiological responses and manifested in facial, vocal, and gestural expressions, before ( c) conscious representation or experience of these changes (feeling) and ( d) categorizing and labeling these changes according to the semantic profiles of emotion words. The review focuses on empirical, particularly experimental, studies from emotion research and neighboring domains that contribute to a better understanding of the unfolding emotion process and the underlying mechanisms, including the interactions among emotion components.

Specificity of Reward Sensitivity and Parasympathetic-Based Regulation among Children with Attention-Deficit/Hyperactivity and Disruptive Behavior Disorders

Attention-deficit/hyperactivity disorder (ADHD) is associated with disruptionsin reward sensitivity and regulatory processes. However, it is unclear whether thesedisruptions are better explained by comorbid disruptive behavior disorder (DBD)symptomology. This study sought to examine this question using multiple levels ofanalysis (i.e., behavior, autonomic reactivity). One hundred seventeen children (aged 6 to 12 years; 72.6% male; 69 with ADHD) completed theBalloon-Analogue Risk Task (BART) to assess external reward sensitivity behaviorally.Sympathetic-based internal reward sensitivity and parasympathetic-based regulationwere indexed via cardiac pre-ejection period (PEP) and respiratory sinus arrhythmia(RSA), respectively. Children with ADHD exhibited reduced internal reward sensitivity (i.e.,lengthened PEP; F(1,112)=4.01, p=0.047) compared to healthy controls and werecharacterized by greater parasympathetic-based dysregulation (i.e., reduced RSAaugmentation F(1,112)=10.12, p=0.002). However, follow-up analyses indicated theADHD effect was better accounted for by comorbid DBD diagnoses; that is, childrenwith ADHD and comorbid ODD were characterized by reduced internal rewardsensitivity (i.e., lengthened PEP; t=2.47, p=0.046) and by parasympathetic-baseddysregulation (i.e., reduced RSA augmentation; t=3.51, p=0.002) in response to rewardwhen compared to typically developing youth. Furthermore, children with ADHD and comorbid CD exhibited greater behaviorally-based external reward sensitivity (i.e.,more total pops; F(3,110)= 5.96, p=0.001) compared to children with ADHD only (t=3.87, p=0.001) and children with ADHD and ODD (t=3.56, p=0.003). Results suggest that disruptions in sensitivity to reward may be betteraccounted for, in part, by comorbid DBD.Key Words: attention-deficit/hyperactivity disorder, autonomic nervous system,disruptive behavior disorders, reward sensitivityPowered.

Prime visibility moderates implicit anger and sadness effects on effort-related cardiac response

Based on the Implicit-Affect-Primes-Effort (IAPE) model (Gendolla, 2012, 2015), an experiment investigated the effect of affect primes' visibility on effort mobilization during cognitive processing. Participants worked on a short-term memory task with integrated sadness vs. anger primes that were presented suboptimally (briefly and masked) vs. optimally (long and visible). Effort was assessed as cardiovascular response, especially cardiac pre-ejection period (PEP). To monitor performance, we assessed response accuracy and reaction times. In accordance with the IAPE model, PEP reactivity was stronger in the sadness-prime condition than in the anger-prime condition-but only when the primes were suboptimally presented. Effects on response accuracy revealed a corresponding pattern. The results suggest that prime visibility is a boundary condition of anger and sadness primes' effect on effort mobilization.

Viewing sexual images is associated with reduced physiological arousal response to gambling loss

Erotic imagery is one highly salient emotional signal that exists everywhere in daily life. The impact of sexual stimuli on human decision-making, however, has rarely been investigated. This study examines the impact of sexual stimuli on financial decision-making under risk. In each trial, either a sexual or neutral image was presented in a picture categorization task before a gambling task. Thirty-four men made gambling decisions while their physiological arousal, measured by skin conductance responses (SCRs), was recorded. Behaviorally, the proportion of gambling decisions did not differ between the sexual and neutral image trials. Physiologically, participants had smaller arousal differences, measured in micro-siemen per dollar, between losses and gains in the sexual rather than in the neutral image trials. Moreover, participants’ SCRs to losses relative to gains predicted the proportion of gambling decisions in the neutral image trials but not in the sexual image trials. The results were consistent with the hypothesis that the presence of emotionally salient sexual images reduces attentional and arousal-related responses to gambling losses. Our results are consistent with the theory of loss attention involving increased cognitive investment in losses compared to gains. The findings also have potential practical implications for our understanding of the specific roles of sexual images in human financial decision making in everyday life, such as gambling behaviors in the casino.

Influence of lighting color temperature on effort-related cardiac response

Higher color temperature refers to a higher proportion of blue spectral components of light, that are known to be associated with higher alertness state in humans. Based on motivational intensity theory (Brehm & Self, 1989), here we predicted that this lighting-induced alertness state should inform about the readiness to perform and this way influence subjective task demand and thus mental effort. To test this, study participants spent 15min under one of four lighting color temperature conditions and then performed a cognitive task. As predicted, effort-related cardiac response, indexed by a shortened cardiac pre-ejection period, decreased with increasing color temperature of light, as indicated by a significant single planned linear contrast. These results demonstrate that spectral properties of light can influence mental effort mobilization.

Preejection Period as a Sympathetic Activity Index: a Role of Confounding Factors

In previous studies, one of the systolic time intervals – preejection period (PEP) – was used as an index of sympathetic activity reflecting the cardiac contractility. However, PEP could be also influenced by several other cardiovascular variables including preload, afterload and diastolic blood pressure (DBP). The aim of this study was to assess the behavior of the PEP together with other potentially confounding cardiovascular system characteristics in healthy humans during mental and orthostatic stress (head-up tilt test – HUT). Forty-nine healthy volunteers (28 females, 21 males, mean age 18.6 years (SD=1.8 years)) participated in the study. We recorded finger arterial blood pressure by volume-clamp method (Finometer Pro, FMS, Netherlands), PEP, thoracic fluid content (TFC) – a measure of preload, and cardiac output (CO) by impedance cardiography (CardioScreen® 2000, Medis, Germany). Systemic vascular resistance (SVR) – a measure of afterload – was calculated as a ratio of mean arterial pressure and CO. We observed that during HUT, an expected decrease in TFC was accompanied by an increase of PEP, an increase of SVR and no significant change in DBP. During mental stress, we observed a decrease of PEP and an increase of TFC, SVR and DBP. Correlating a change in assessed measures (delta values) between mental stress and previous supine rest, we found that ΔPEP correlated negatively with ΔCO and positively with ΔSVR. In orthostasis, no significant correlation between ΔPEP and ΔDBP, ΔTFC, ΔCO, ΔMBP or ΔSVR was found. We conclude that despite an expected increase of sympathetic activity during both challenges, PEP behaved differently indicating an effect of other confounding factors. To interpret PEP values properly, we recommend simultaneously to measure other variables influencing this cardiovascular measure.

Impedance cardiography in healthy children and children with congenital heart disease: Improving stroke volume assessment

INTRODUCTION

Stroke volume (SV) and cardiac output are important measures in the clinical evaluation of cardiac patients and are also frequently used in research applications. This study was aimed to improve SV scoring derived from spot-electrode based impedance cardiography (ICG) in a pediatric population of healthy volunteers and patients with a corrected congenital heart defect.

METHODS

128 healthy volunteers and 66 patients participated. First, scoring methods for ambiguous ICG signals were optimized to improve agreement of B- and X-points with aortic valve opening/closure in simultaneously recorded transthoracic echocardiography (TTE). Building on the improved scoring of B- and X-points, the Kubicek equation for SV estimation was optimized by testing the agreement with the simultaneously recorded SV by TTE. Both steps were initially done in a subset of the sample of healthy children and then validated in the remaining subset of healthy children and in a sample of patients.

RESULTS

SV assessment by ICG in healthy children strongly improved (intra class correlation increased from 0.26 to 0.72) after replacing baseline thorax impedance (Z₀) in the Kubicek equation by an equation (7.337-6.208∗dZ/dt_max), where dZ/dt_max is the amplitude of the ICG signal at the C-point. Reliable SV assessment remained more difficult in patients compared to healthy controls.

CONCLUSIONS

After proper adjustment of the Kubicek equation, SV assessed by the use of spot-electrode based ICG is comparable to that obtained from TTE. This approach is highly feasible in a pediatric population and can be used in an ambulatory setting.