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Early stressful events negatively affect emotional and physical well-being. Cardiac vagal tone (CVT), which is associated with better emotional and physical well-being, usually gradually increase in early childhood. Nonetheless, children's CVT developmental trajectories are greatly variable, such that CVT can increase or decrease across the years. The present study examines the longitudinal effects of early stressful events and the role of 4 years CVT developmental trajectory on children's emotional and physical well-being. Forty-two 4-year-old children were enrolled. Number of stressful events and resting electrocardiogram (ECG) were collected at T1. ECG was registered again after one (T2), two (T3) and three (T4) years. Children's emotional and physical well-being were assessed at T4 through the Child Health and Illness Profile - Child Edition (CHIP-CE). CVT development was calculated as the angular coefficient, reflecting the developmental trajectory of CVT across the four timepoints. Results yielded that higher experienced stressful events predicted poorer emotional and physical well-being after 4 years. The interaction between the number of stressful events and CVT development emerged on physical well-being. Early stressful events negatively affect long-term children's emotional and physical well-being while a positive CVT development seems to mitigate the negative effects of early stressful events on physical well-being.

Background: The vagus nerve exerts an anti-nociceptive effect on the viscera. Aim: To investigate whether transcutaneous vagal nerve stimulation (t-VNS) prevents the development of and/or reverses established visceral hypersensitivity in a validated model of acid-induced oesophageal pain. Methods: Before and after a 30-minute infusion of 0.15M hydrochloric acid into the distal oesophagus, pain thresholds to electrical stimulation were determined in the proximal non-acid exposed oesophagus. Validated sympathetic (cardiac sympathetic index) and parasympathetic (cardiac vagal tone [CVT]) nervous system measures were recorded. In study 1, 15 healthy participants were randomised in a blinded crossover design to receive either t-VNS or sham for 30 minutes during acid infusion. In study 2, 18 different healthy participants were randomised in a blinded crossover design to receive either t-VNS or sham, for 30 minutes after acid infusion. Results: Study 1: t-VNS increased CVT (31.6% ± 58.7 vs −9.6 ± 20.6, P = 0.02) in comparison to sham with no effect on cardiac sympathetic index. The development of acid-induced oesophageal hypersensitivity was prevented with t-VNS in comparison to sham (15.5 mA per unit time (95% CI 4.9 - 26.2), P = 0.004). Study 2: t-VNS increased CVT (26.3% ± 32.7 vs 3 ± 27.1, P = 0.03) in comparison to sham with no effect on cardiac sympathetic index. t-VNS reversed established acid-induced oesophageal hypersensitivity in comparison to sham (17.3mA/unit time (95% CI 9.8-24.7), P = 0.0001). Conclusions: t-VNS prevents the development of, and reverses established, acid-induced oesophageal hypersensitivity. These results have therapeutic implications for the management of visceral pain hypersensitivity.

Slow, deep breathing is being used as a self-management intervention for various health conditions including pain and hypertension. Stimulation of the arterial baroreceptors and increased vagal modulation are among the proposed mechanisms for the therapeutic effects of slow, deep breathing. We investigated whether adding inspiratory threshold load can enhance the cardiovascular responses to controlled breathing at the frequency of 0.1 Hz, a common form of slow, deep breathing. Healthy volunteers (N = 29) performed controlled breathing at 0.1 Hz (6 breaths/minute) without load and with inspiratory threshold loads of 5 cmH2 O and 10 cmH2 O. Respiratory airflow, heart rate, and blood pressure were continuously recorded. The amplitude of the systolic blood pressure variation during respiratory cycles increased with increasing loads. Respiratory sinus arrhythmia was higher during controlled breathing at 0.1 Hz with the load of 10 cmH2 O compared to without load. Baroreflex sensitivity was not affected by loads. The effect of loads on respiratory sinus arrhythmia was mediated by increasing the amplitude of systolic blood pressure variation during respiratory cycles. These results suggest that applying small inspiratory threshold loads during controlled breathing at 0.1 Hz increases cardiac vagal modulation by this breathing exercise. This effect seems to be mediated by stronger stimulation of the arterial baroreceptors because of larger systolic blood pressure swings along the respiratory cycle. The potential benefit of long-term practice of controlled breathing at 0.1 Hz with inspiratory threshold loads on baroreflex function and cardiac vagal control needs to be investigated, particularly in pain and hypertension patients.

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.

Vagally mediated heart rate variability (vmHRV) is a measure of cardiac vagal tone, and is widely viewed as a physiological index of the capacity to regulate emotions. However, studies have not directly tested whether vmHRV is associated with the ability to facially express emotions. In extending prior work, the current report tested links between resting vmHRV and the objectively assessed ability to facially express emotions, hypothesizing that higher vmHRV would predict greater expressive skill. Eighty healthy women completed self-reported measures, before attending a laboratory session in which vmHRV and the ability to express six emotions in the face were assessed. A repeated measures analysis of variance revealed a marginal main effect for vmHRV on skill overall; individuals with higher resting vmHRV were only better able to deliberately facially express anger and interest. Findings suggest that differences in resting vmHRV are associated with the objectively assessed ability to facially express some, but not all, emotions, with potential implications for health and well-being.

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.

We examined whether cardiac vagal tone (indexed by heart rate variability, HRV) was associated with the functioning of selective attention under load. Participants were instructed to detect a target letter among letter strings superimposed on either fearful or neutral distractor faces. Under low load, when letter strings consisted of six target letters, there was no difference between people with high and low HRV on task performance. Under high load, when letter strings consisted of one target letter and five nontarget letters, people with high HRV were faster in trials with neutral distractors, but not with fearful distractors. However, people with low HRV were slower in trials with both fearful and neutral distractors. The current research suggests cardiac vagal tone is associated with successful control of selective attention critical for goal-directed behavior, and its impact is greater when fewer cognitive resources are available.

The study investigated interactions between autonomic cardiovascular regulation and cortical activity. In 54 healthy subjects, baroreflex sensitivity (BRS) and respiratory sinus arrhythmia (RSA) were assessed at resting conditions. As an EEG indicator of cortical excitability, the contingent negative variation (CNV) was induced using a constant foreperiod reaction time task. At bivariate level, only RSA showed a moderate positive correlation with the CNV recorded at frontal electrodes. However, when common variance of BRS and RSA was controlled for in multiple regression analysis, an inverse association between BRS and the frontal CNV also arose. The inverse association between BRS and the CNV is discussed as reflecting bottom-up modulation of cortical excitability by baroreceptor afferents. The positive correlation between RSA and the CNV may relate to the interplay between prefrontal processing and cardiac vagal tone.

We conducted a theoretical study of the physiological significance of respiratory sinus arrhythmia (RSA), a phenomenon used as an index of cardiac vagal tone and wellbeing, whereby the heart rate (HR) increases during inspiration and decreases during expiration. We first tested the hypothesis that RSA improves gas exchange efficiency but found that although gas exchange efficiency improved with slow and deep breathing and with increased mean heart rate, this was unrelated to RSA. We then formulated and tested a new hypothesis: that RSA minimizes the work done by the heart while maintaining physiological levels of arterial carbon dioxide. We tested the new hypothesis using two methods. First, the HR for which the work is minimized was calculated using techniques from optimal control theory. This calculation was done on simplified models that we derived from a previously published model of gas exchange in mammals. We found that the calculated HR was remarkably similar to RSA and that this became more profound under slow and deep breathing. Second, the HR was prescribed and the work done by the heart was calculated by conducting a series of numerical experiments on the previously published gas exchange model. We found that cardiac work was minimized for RSA-like HR functions, most profoundly under slow and deep breathing. These findings provide novel insights into potential reasons for and benefits of RSA under physiological conditions.

Cardiac vagal tone, as indexed by abnormalities in the level and/or reactivity of respiratory sinus arrhythmia (RSA), has been related to psychiatric impairment, including risk for depression. Longitudinal studies of depression have focused on RSA levels and have found mixed support for the hypothesis that low RSA levels predict a more pernicious course of depression. The current investigation focuses on the relation between RSA reactivity and the course of depression. We measured depressed persons' RSA reactivity to sadness-, fear-, and amusement-inducing emotion films and reassessed participants' diagnostic status 6 months later. Depressed persons who exhibited a higher degree of vagal withdrawal to the sad film were more likely to recover from depression. Implications for the study of RSA in depression are discussed.

In dogs with spontaneous heart disease, an electronically generated measurement of cardiac vagal tone, the cardiac index of parasympathetic activity, was a sensitive, simple and inexpensive measure of the severity of heart failure. Dogs with cardiac disease and an index score less than 3 were at 15.8 (95 per cent confidence interval 2.9 to 87.2) times the risk of dying within a year than those with a score of 3 and over. The measurement of the index provided an objective and reliable beat-by-beat measurement of cardiac vagal tone, which was prognostically useful in dogs with heart disease.

This study is an investigation of linkages between marital quality (conflict and harmony)and infants' emotional and physiological regulation. It was hypothesized that infants exposed to greater levels of marital conflict would demonstrate lower levels of emotional and physiological regulation. Fifty-six low-risk infants and their mothers attended a laboratory session when infants were 6 months of age. A baseline EKG was gathered to assess infants' cardiac vagal tone and the Bayley Scales of Infant Development and Behavior Rating Scales were administered. Mothers also completed Braiker and Kelley's (1979) marital quality questionnaire. Consistent with past research with preschoolers, marital conflict was found to be linked to lower levels of emotion regulation in infants. However, unlike past research (Gottman & Katz, 1989), results indicated that marital conflict was associated with lower levels of cardiac vagal tone in infants as opposed to higher levels of vagal tone among preschoolers. These findings a...

Objective: We studied the effect of weight reduction on cardiac parasympathetic activity (PSA) in obese women. We also studied the relationship between the changes of PSA, resting energy expenditure (REE), and major cardiovascular risk factors. Research Methods and Procedures: Changes of cardiac vagal tone, an index of PSA, REE, and major cardiovascular risk factors, were measured in 52 healthy obese women after a 6-month weight reduction. Ten of the women were remeasured at 12 and 24 months. Cardiac vagal tone was assessed by a vagal tone monitor and REE by indirect calorimeter. Results: Cardiac vagal tone increased significantly (p = 0.046), averaging a 9.5% weight loss in 6 months. The vagal tone increased further with weight loss during the following 6 months, and thereafter, it declined with weight regain. The increase of cardiac vagal tone correlated significantly with decreases of body weight, fat mass, waist circumference, serum insulin, and heart rate. REE adjusted for fat-free mass and age did not change with weight loss and was not related to cardiac vagal tone at any time-point. Discussion: Cardiac PSA activity increases with weight loss in obese women. This increase may not be maintained long-term if body weight is regained. The rise of cardiac PSA is correlated with decreases of body fat mass, abdominal fat, serum insulin, and heart rate. Cardiac PSA is not related to REE.

The goal of the present study was to test a recent hypothesis that the ability to suppress cardiac vagal tone during a cognitive challenge was related to social behavior. One hundred thirty-six infants participated with their parents in laboratory visits when infants were 12 (mother visit) and 13 months (father visit) of age. To measure the infants’ regulation of cardiac vagal tone, heart rate responses were recorded during the administration of a test of mental development (father visit). Responses to a stranger interaction were measured during the 12 month visit. In addition, experimenters evaluated the infants’ behavior across the laboratory sessions using an adaptation of the Infant Behavior Record. Results revealed that infants who were able to suppress vagal tone during the cognitive challenge were rated by the experimenters as more socially approaching at the two laboratory visits. Vagal regulation was unrelated to behavior during the stranger-infant interaction. These findings partially support the hypothesis that infants who are able to regulate their vagal tone have a greater capacity for social engagement.

The present study examined the relation between early emotion regulation and later compliance. When infants were 5, 10, and 18 months of age, they participated in a frustration task. The degree to which they reacted negatively to the stimuli and the behaviors they used to regulate that response were coded. Baseline heart rate also was recorded and a measure of cardiac vagal tone (VNA) was derived. Several tasks (electrode placement, toy clean-up, and test situation) were administered to elicit compliance/noncompliance when the participants were 30 months of age. Results revealed that infants who demonstrated low levels of regulatory behavior were more likely to be noncompliant as toddlers. Several interaction effects suggested that the prediction to later noncompliance was also dependent upon the infants' level of reactivity. Cardiac vagal tone also was related to compliance but in a contradictory fashion. High VNA was related to noncompliance to toy clean-up, whereas low VNA was related to noncompliance to electrode placement. The data provide support for a developmental model of compliance that includes the ability to regulate emotional arousal.

Sixty 12-week-old infants participated in a laboratory study to explore the relations between temperament and cardiac vagal tone. Temperament was evaluated via laboratory observations and maternal ratings. Cardiac vagal tone, measured as the amplitude of respiratory sinus arrhythmia, was quantified from beat-to-beat heart period data collected during a resting baseline period and during the laboratory assessment of temperament. Specific hypotheses were investigated relating temperament to both basal cardiac vagal tone and changes in cardiac vagal tone during social/attention challenges. Infants with higher baseline cardiac vagal tone were rated in the laboratory as showing fewer negative behaviors and were less disrupted by the experimental procedure. Infants who decreased cardiac vagal tone during the laboratory assessment were rated on maternal report temperament scales as having longer attention spans, and being more easily soothed.

The relation between two dimensions of vagal tone (Vna), indexed by a baseline measure of Vna and suppression of Vna and temperamental reactivity and behavioral regulation was investigated. Forty-one children were observed during a series of episodes designed to elicit temperamental reactivity and behavioral regulation. Heart rate was recorded during these baseline, positive, negative, and delay episodes, from which measures of vagal tone were computed. Across the entire sample, vagal tone decreased from the baseline episode to the three affect tasks. Baseline measures of vagal tone were related to the tendency to show a decrease in vagal tone: Children who consistently suppressed vagal tone (showed a decrease to all the affect tasks) had higher baseline vagal tone. Baseline vagal tone was related to temperamental reactivity for the positive and negative tasks, but not the delay tasks. Vagal suppression (vagal difference score) was related to several of the behavioral regulation strategies used by the children in the affect-eliciting situations. These findings are discussed in terms of the adaptive value of physiological regulation in the development of regulatory behaviors that may be critical to social development.

Cardiac vagal tone is a construct that describes the functional relationship between the brainstem and the heart. Cardiac vagal tone is measured by quantifying the amplitude of respiratory sinus arrhythmia, a component of heart rate variability reflecting the functional output of vagal pathways on the heart. Although there is an extensive literature evaluating baseline vagal tone and its relation to behavior, the relation between individual differences in the ability to regulate cardiac vagal tone and behavior has been theoretically vague. This article introduces a theoretical model to explain the relation between vagal tone during steady states and vagal reactivity (i.e., the vagal brake) in response to environmental challenges. Based upon the proposed model, it was hypothesized that infants who had difficulties in regulating the vagal brake (i.e., decreasing cardiac vagal tone) during social/attention tasks would have difficulties developing appropriate social interactions requiring reciprocal engagement and disengagement strategies. Data from 24 infants are presented. The findings support the model and demonstrate that infants with difficulties in decreasing vagal tone during a social/attention task at 9 months of age had significantly more behavioral problems at 3 years of age.

The stability of infant temperament and autonomic patterning (heart period and cardiac vagal tone) was examined longitudinally when infants were 5, 10, and 18 months of age. Behavioral measures of reactivity and regulation to frustration tasks, and maternal perceptions of infant temperament were obtained at each age along with baseline measures of cardiac activity. No stability was found from 5 to 10 months while some stability of behavior and autonomic patterning was identified from 10 to 18 months, with the exception of negative reactivity. High levels of cardiac vagal tone (V) were associated with negative reactivity at 18 months. When examining groups based on degrees of reactivity and regulation, we found infants who responded negatively to frustration but who also displayed more regulatory behavior to have higher V.

Mothers classified as ‘depressed’, ‘non-depressed’ or ‘low scoring’ on the Beck Depression Inventory and their 3-month-old infants were videotaped during 3-minute face-to-face play interactions. Infants' facial expressions were coded using the AFFEX facial expression coding system and their EKG was recorded during the interactions to assess the relationship between cardiac measures and facial expressivity. Infants of both ‘depressed’ and ‘low scoring’ mothers showed significantly more sad and anger expressions and fewer interest expressions than infants of nondepressed mothers. Cardiac vagal tone, (quantified from the amplitude of respiratory sinus arrhythmia) was correlated with infants' joy and interest expressions and with self-comfort behaviours in the non-depressed and low scoring groups, but not in the depressed group. The results suggest that matermal depression affects infants' affective state and appearance as well as their biobehavioural emotional regulation systems.

In a recent Classical Perspectives article in The Journal of Physiology (Joyner, 2005), Mike Joyner summarizes his perspective of the contribution of a paper by McCloskey & Mitchell (1972). This does an excellent job of highlighting an area of research that continues to be important to this day and often throws up surprises. Unfortunately the account contains some inaccuracies and also overlooks key contributions from British scientists. An almost similar paper to the one above was published in 1971 in The Journal of Physiology (Coote et al. 1971). Our paper was the first to report the use of ventral root stimulation to evoke contraction of muscles and we did this in anaesthetized as well as in decerebrate cats (see also Coote et al. 1969). One particular difference in the paper by McCloskey and Mitchell was that they very elegantly showed that it was muscle afferent fibre Goup III and IV that were responsible but this was hardly surprising since with Perez-Gonzalez in 1970 I had published our studies on the effects on blood pressure and renal sympathetic nerve activity of stimulating muscle afferents of different sizes showing that only these small fibres were involved (Coote & Perez-Gonzalez, 1970). So I think Mike Joyner was going a little too far in implying that we didn't know these facts before the McCloskey and Mitchell paper. In tracing the history of what has subsequently occurred I think attention should have been drawn to an important study by Mike White and Richard Bull, which showed that similar blood pressure and heart rate effects can be evoked to voluntary contraction by electrically induced contraction of muscle (Bull et al. 1989). A significant finding in the latter paper was that in a post-contraction occlusion of the muscle circulation the blood pressure remained increased whilst the heart rate returned to base line, a phenomena that we have recently concluded can be explained by the differing actions of muscle Group III mechanoreceptors mainly affecting cardiac vagal tone whilst Group IV metaboreceptors mainly affect sympathetic tone (Gladwell & Coote, 2002; Gladwell et al. 2005). As to the way the afferent information converges Joyner does not draw attention to the beautiful studies of Peter McWilliams' group in Leeds, which in 1991–92, was already clearly demonstrating that the heart rate increase to muscle contraction was greater when cardiac vagal tone was increased by raising baroreceptor input. Furthermore, they showed that electrical stimulation of muscle nerves activated GABA neurones in the NTS and blocked baroreceptor excited units (McWilliam & Yang, 1991; McMahon & McWilliam, 1992; McMahon et al. 1992).We still do not know whether this is the primary site for interaction between muscle afferents and the baroreceptor reflex but the differential effect on heart rate and blood pressure of the muscle afferents might point to an influence in addition closer to the cardiac vagal neurones. I hope this sets the record straight although I accept that mine, like Mike Joyner's, is a biased viewpoint.