Multiple modes of operation of cardiac autonomic control: development of the ideas from Cannon and Brooks to the present

Publication guidelines for human heart rate and heart rate variability studies in psychophysiology-Part 1: Physiological underpinnings and foundations of measurement

This Committee Report provides methodological, interpretive, and reporting guidance for researchers who use measures of heart rate (HR) and heart rate variability (HRV) in psychophysiological research. We provide brief summaries of best practices in measuring HR and HRV via electrocardiographic and photoplethysmographic signals in laboratory, field (ambulatory), and brain-imaging contexts to address research questions incorporating measures of HR and HRV. The Report emphasizes evidence for the strengths and weaknesses of different recording and derivation methods for measures of HR and HRV. Along with this guidance, the Report reviews what is known about the origin of the heartbeat and its neural control, including factors that produce and influence HRV metrics. The Report concludes with checklists to guide authors in study design and analysis considerations, as well as guidance on the reporting of key methodological details and characteristics of the samples under study. It is expected that rigorous and transparent recording and reporting of HR and HRV measures will strengthen inferences across the many applications of these metrics in psychophysiology. The prior Committee Reports on HR and HRV are several decades old. Since their appearance, technologies for human cardiac and vascular monitoring in laboratory and daily life (i.e., ambulatory) contexts have greatly expanded. This Committee Report was prepared for the Society for Psychophysiological Research to provide updated methodological and interpretive guidance, as well as to summarize best practices for reporting HR and HRV studies in humans.

The sympathies of the body: functional organization and neuronal differentiation in the peripheral sympathetic nervous system

During the last 30 years, our understanding of the development and diversification of postganglionic sympathetic neurons has dramatically increased. In parallel, the list of target structures has been critically extended from the cardiovascular system and selected glandular structures to metabolically relevant tissues such as white and brown adipose tissue, lymphoid tissues, bone, and bone marrow. A critical question now emerges for the integration of the diverse sympathetic neuron classes into neural circuits specific for these different target tissues to achieve the homeostatic regulation of the physiological ends affected.

Diverse Autonomic Nervous System Stress Response Patterns in Childhood Sensory Modulation

The specific role of the autonomic nervous system (ANS) in emotional and behavioral regulation—particularly in relation to automatic processes—has gained increased attention in the sensory modulation literature. This mini-review article summarizes current knowledge about the role of the ANS in sensory modulation, with a focus on the integrated functions of the ANS and the hypothalamic-pituitary-adrenal (HPA) axis and their measurement. Research from the past decade illustrates that sympathetic and parasympathetic interactions are more complex than previously assumed. Patterns of ANS activation vary across individuals, with distinct physiological response profiles influencing the reactivity underlying automatic behavioral responses. This review article advances a deeper understanding of stress and the complex stress patterns within the ANS and HPA axis that contribute to allostatic load (AL). We argue that using multiple physiological measurements to capture individual ANS response variation is critical for effectively treating children with sensory modulation disorder (SMD) and sensory differences. We consider the relative contributions of automatic vs. deliberately controlled processes across large-scale neural networks in the development of sensorimotor function and their associated links with arousal patterns and sensory over- and under-responsivity.

Sympathetic tales: subdivisons of the autonomic nervous system and the impact of developmental studies

Remarkable progress in a range of biomedical disciplines has promoted the understanding of the cellular components of the autonomic nervous system and their differentiation during development to a critical level. Characterization of the gene expression fingerprints of individual neurons and identification of the key regulators of autonomic neuron differentiation enables us to comprehend the development of different sets of autonomic neurons. Their individual functional properties emerge as a consequence of differential gene expression initiated by the action of specific developmental regulators. In this review, we delineate the anatomical and physiological observations that led to the subdivision into sympathetic and parasympathetic domains and analyze how the recent molecular insights melt into and challenge the classical description of the autonomic nervous system.

Is heart rate variability affected by distinct motor imagery strategies?

Although some studies have reported significant changes in autonomic responses according to the perspective-taking during motor imagery [first person perspective (1P) and third person perspective (3P)], investigations on how the strategies adopted to mentally simulate a given movement affect the heart rate variability (HRV) seem so far unexplored. Twenty healthy subjects mentally simulated the movement of middle-finger extension in 1P and 3P, while electrocardiogram was recorded. After each task, the level of easiness was self-reported. Motor imagery ability was also assessed through the revised version of Movement Imagery Questionnaire (MIQ-R) and a mental chronometry index. The traditional measures of HRV in the time- and frequency-domain were compared between 1P and 3P tasks by using Student's t-test for dependent samples. The MIQ-R results showed that subjects had the same facility to imagine movements in 1P or 3P. The mental chronometry index revealed a similar temporal course only between 1P and execution, while the 3P strategy had a shorter duration. Additionally, the subjective report was similar between the experimental tasks. Regarding the HRV measures, the low frequency component, in log-transformed unit, was significantly higher (p=0.017) in 1P than 3P, suggesting a higher activity of the sympathetic system during 1P. This log-transformed HRV parameter seems to be more sensitive than normalized values for the assessment of the motor imagery ability, together with questionnaires, scales and mental chronometry.

A composite autonomic index as unitary metric for heart rate variability: a proof of concept

BACKGROUND

This study addresses whether a unitary cardiac autonomic nervous system index (ANSI), obtained combining multiple metrics from heart rate variability (HRV) into a radar plot could provide an easy appreciation of autonomic performance in a clinical setting.

MATERIALS AND METHODS

Data are standardized using percentile ranking of autonomic proxies from a relatively large reference population (n = 1593, age 39 ± 13 years). Autonomic indices are obtained from autoregressive spectral analysis of (ECG derived) HRV at rest and during standing up. A reduced ANSI (using RR, RR variance and rest-stand difference of LFnu) is then constructed as a radar plot, quantified according to its combined area and tested against different risk subgroups.

RESULTS

With growing risk profile, there is a marked reduction of the rank value of ANSI, quantified individually by the radar plot area. The practical usefulness of the approach was tested in small groups of additional subjects putatively characterized by elevated or poor autonomic performance. Data show that elite endurance athletes are characterized by elevated values of ANSI (80·6 ± 14·9, P < 0·001) while subjects with either Type 1 or Type 2 diabetes show lower values (DM1 = 37·0 ± 18·9 and DM2 = 26·8 ± 23·3, P = 0·002), and patients with coronary artery disease (CAD) represent a nadir (17 ± 20, P < 0·001).

CONCLUSIONS

This observational study shows the feasibility of testing simpler metrics of cardiac autonomic regulation based on a multivariate unitary index in a preventive setting. This simple approach might foster a wider application of HRV in the clinical arena, and permit an easier appreciation of autonomic performance.

Perfectionism and Effort-Related Cardiac Activity: Do Perfectionists Try Harder?

Do perfectionists try harder? Previous research on perfectionism and effort has used self-report items and task performance as indicators of effort. The current study investigated whether individual differences in perfectionism predicted effort-related cardiac activity during a mental effort task. Based on past research that suggests adaptive perfectionism is associated with higher effort, it was hypothesized that self-oriented perfectionism (SOP) would predict increased effort on the task. One hundred and eleven college students completed the Multidimensional Perfectionism Scale (MPS) and a self-paced parity task in which they received a small cash reward (3 cents) for each correct response. Impedance cardiography was used to assess autonomic reactivity, and regression models tested whether SOP and socially prescribed perfectionism (SPP) explained autonomic reactivity. Overall, participants showed both sympathetic (faster pre-ejection period; PEP) and parasympathetic activation (elevated high-frequency heart rate variability; HRV) during the task, reflecting higher effort and engagement. Contrary to predictions, individual differences in perfectionism did not moderate cardiac reactivity. These findings draw attention to the importance of assessing physiological components of effort and motivation directly rather than inferring them from task performance or self-reported effort.

Cardiorespiratory Regulation in Migraine. Results in Children and Adolescents and Review of the Literature

To investigate autonomic regulation in juvenile migraine we studied 70 children and adolescents with migraine during the headache-free period and 81 healthy controls by cardiorespiratory function tests. Heart rate variability was analysed with time and frequency domain indices during spontaneous breathing at rest and during metronomic breathing. Changes of heart rate and blood pressure were studied during tilt-table test, active standing, Valsalva manoeuvre and sustained handgrip. We found significant differences in metronomic breathing, tilt-table test and Valsalva manoeuvre. We interpret our findings and results reported in the literature as pointing to a restricted ability of the system to rest, which supports therapies intending to further this ability. In autonomic tests, hyperreactivity in juvenile migraineurs changes to hyporeactivity and passive coping in adults. This might be explained by disturbances of raphe nuclei and the periaqueductal grey. It corresponds to psychological findings in juvenile migraineurs reporting hypersensitivity and repressed aggression and claiming learned helplessness.

Gritty people try harder: grit and effort-related cardiac autonomic activity during an active coping challenge

Grit, a recently proposed personality trait associated with persistence for long-range goals, predicts achievement in a wide range of important life outcomes. Using motivational intensity theory, the present research examined the physiological underpinnings of grit during an active coping task. Forty young adults completed the Short Grit Scale and worked on a self-paced mental effort task. Effort-related autonomic nervous system (ANS) activity was assessed using impedance cardiography, which yielded measures of sympathetic activity (pre-ejection period; PEP) and parasympathetic activity (respiratory sinus arrhythmia; RSA). Multilevel models revealed that people high on the Perseverance of Effort subscale showed autonomic coactivation: both PEP and RSA became stronger during the task, reflecting higher activity of both ANS divisions. The Consistency of Interest subscale, in contrast, predicted only weaker sympathetic activity (slower PEP). Taken together, the findings illuminate autonomic processes associated with how "gritty" people pursue goals, and they suggest that more attention should be paid to the facets' distinct effects.

Mechanisms of neurohormonal activation in chronic congestive heart failure: pathophysiology and therapeutic implications

Patients with chronic congestive heart failure have a sequential and incessant activation of those neurohormonal systems, which control body fluids, cardiac output and systemic blood pressure. Neurohormonal activation is initially selective and regional. Generalized activation is a late event in the natural history of congestive heart failure. Although the ultimate stimulus responsible for the activation of these neurohormonal systems is unknown, a decreased cardiac output and diminished effective blood volume have been proposed as the responsible mechanisms. However, extensive clinical and experimental research suggest that cardiac remodeling and loading of low-pressure cardiac receptors with sympathetic afferents could be the triggering events followed by unloading of high-pressure carotid receptors by decreased cardiac output and diminished effective blood volume.

Autonomic response patterns observed during the performance of an attention-demanding task in two groups of children with autistic-type difficulties in social adjustment

Two groups of children with autistic-type behavior problems were compared to a group of normal children with respect to their autonomic response patterns observed during the performance of an attention-demanding task. Heart rate, blood pressure, and respiratory activity were measured during periods of rest and of task performance. Applying a quantitative model of the baroreflex, we were able to demonstrate qualitative differences among the groups with respect to their vagally controlled response patterns, whereas sympathetic responsiveness did not differ. In terms of our model, the groups with autistic-type behavior showed a decrease in central vagal tone during task performance, while vagal gain appeared to be unaffected or even increased. In contrast, the children in the control group showed the expected pattern of a decrease in vagal gain while vagal tone appeared to be increased. Implications of our findings are discussed in the light of Damasio's somatic marking hypothesis.

Differences in autonomic physiological responses between good and poor inductive reasoners

We investigated individual- and task-related differences in autonomic physiological responses induced by time limited figural and verbal inductive reasoning tasks. In a group of 52 participants, the percentage of correctly responded task items was evaluated together with nine different autonomic physiological response measures and respiration rate (RR). Weighted multidimensional scaling analyses of the physiological responses revealed three underlying dimensions, primarily characterized by RR, parasympathetic, and sympathetic activity. RR and sympathetic activity appeared to be relatively more important response dimensions for poor reasoners, whereas parasympathetic responsivity was relatively more important for good reasoners. These results suggest that poor reasoners showed higher levels of cognitive processing intensity than good reasoners. Furthermore, for the good reasoners, the dimension of sympathetic activity was relatively more important during the figural than during the verbal reasoning task, which was explained in terms of hemispheric lateralization in autonomic function.

Carotid and aortic baroreflexes of the rat: I. Open-loop steady-state properties and blood pressure variability

To characterize the baroreflex in central nervous system-intact neuromuscular-blocked rats, we measured the vascular and cardiac responses and compared direct stimulation of the aortic depressor nerve (ADN) with a capacitance electrode (differentially activating either A or A + C fibers) to carotid sinus pressure with a micro-balloon (SINUS). One-thousand-two-hundred-ninety-seven open-loop measurements of systolic blood pressure (SBP), heart rate, venous pressure (VBP), and mesenteric (msBF), femoral (fmBF), and skin (skBF) blood flow were completed; the linear range of the effects was determined for each response and stimulus mode. The rats were sinoaortic denervated (SAD). The open-loop stimulation effect was very stable; e.g., the mean effect of 790 ADN stimulations during >7 days was -9.8 mmHg, with an average drift of +0.001 mmHg/h. In contrast, there was large variability of the SBP baseline (e.g., SD = +/-10.9), which was due to SAD (+/-6.3 to +/-16.3 mmHg, t = -13. 9, df = 4, P < 0.0002) and was reversed by ganglionic block (+/-10.8 to +/- 2.9 mmHg, t = -12.9, df = 3, P < 0.001). The ADN stimuli produced larger depressor responses than sinus stimuli (-66 vs. -45 mmHg); all component responses paralleled the magnitude of the SBP effect, except interbeat interval (IBI), for which the ADN DeltaIBI was approximately 10 times that of SINUS. For all stimuli, fmBF increased and msBF did not. Mesenteric and femoral vascular conductance both increased, whereas VBP decreased and skBF followed SBP. We found that for all baroreflex response components, with the exception of SINUS-elicited DeltaIBI, there was an orderly, substantially linear, relationship between stimulus strength and response magnitude.

Autonomic function in the early stage of panic disorder: power spectral analysis of heart rate variability

Previous studies of autonomic nervous system (ANS) function in panic disorder (PD) patients have yielded conflicting results. We speculate that these differences might result from the variety of clinical stages of PD. In order to investigate this, we compared ANS activity in untreated patients in the early stage of PD with control subjects using power spectral analysis of electrocardiogram R-R intervals (PSR-R) in supine rest and during head-up tilt, which was performed according to the maximum entropy method (MEM). It recognizes two main components: high-frequency power (HF), which mainly reflects cardiac parasympathetic activity, and low-frequency power (LF), which reflects both cardiac sympathetic and parasympathetic activity. The patients with PD had significantly higher values for all components of PSR-R only in tilt position total power (TP), LF, and HF than did the control subjects (P<0.01, <0.01, <0.02, respectively). However, the LF/HF ratio which indicated sympathovagal balance did not differ significantly between the two groups in tilt position. Our findings suggest that patients with PD in the early stage of illness have co-activation of sympathetic and parasympathetic nervous systems, which might act to maintain a balance between the two autonomic systems.

Effects of non-invasive stimulation of acupoints on the cardiovascular system

OBJECTIVE

To study the effect of two non-invasive methods to stimulate acupoints on the cardiovascular system.

DESIGN

Blind randomized-controlled trial.

SETTING

An experimental setting in a university-affiliated hospital.

INTERVENTIONS

The subjects (24 healthy male volunteers) were randomized to receive either an active stimulation consisting of pressure on acupoints (P), an active stimulation consisting of stroking along the meridians (S) or a control stimulation (C).

MAIN OUTCOME MEASURES

Data on skin blood flow, arterial pressure, heart rate and EKG were recorded continuously from 20 min before stimulation to 30 min after.

RESULTS

In P group there was a decrease in systolic arterial pressure, diastolic arterial pressure, mean arterial pressure, heart rate and skin blood flow. These changes were significantly different from those in C group and, as regards diastolic pressure and mean pressure, also from those in S group. There were no significant differences between S and C groups.

CONCLUSIONS

Pressure on acupoints can significantly influence the cardiovascular system.

Extrinsic inputs to intrinsic neurons in the porcine heart in vitro

Convergence of inputs from extrinsic cardiac nerves [vagus and cardiopulmonary (CPN)] on intrinsic cardiac neurons was investigated in the pig (Sus scrofa). A segment of the right atrial wall containing epicardial neurons along with attached stumps of the right vagus nerve and CPN was maintained in vitro; intracellular recordings were made from 57 neurons. Three types of neuron were identified by their responses to long intracellular depolarizing current pulses: phasic [discharged 1 action potential (AP); 40%]; accommodating (discharged multiple APs decrementing in frequency during pulse; 33%); and tonic (discharged multiple APs at a high frequency; 27%). Sixty-six percent of the neurons responded with excitatory postsynaptic potentials (EPSP) to vagal nerve stimulation; two-thirds of these cells fired APs when EPSP amplitude exceeded threshold level. Postsynaptic responses to vagal nerve stimulation were mediated by nicotinic ion channels; responses were eliminated by hexamethonium. CPN stimulation produced EPSPs but no APs in 17% of the neurons. All neurons responding with postsynaptic depolarizations to CPN stimulation also received vagal inputs. Combined stimulation of the vagus nerve and CPN produced APs in all but one of these neurons. Timolol eliminated postsynaptic responses from CPN stimulation, indicating that these responses involved beta-adrenergic receptors and likely resulted from activation of sympathetic postganglionic terminals. These results show that some intrinsic cardiac neurons receive convergent inputs from the CPN and vagus nerve. It is suggested that such neurons represent intraganglionic sites for sympathetic-parasympathetic interactions in neural control of the heart.

Anxiety and cardiovascular reactivity: the basal forebrain cholinergic link

The relations between anxiety states and autonomic functions are considered from the vantage of a model of the neural systems underlying anxiety and autonomic control. An important component of this model is the involvement of the basal forebrain cortical cholinergic system that is seen to play a crucial role in the cognitive aspects of anxiety, and the links between anxiety and autonomic regulation. An additional aspect of the model is the detailing of the routes by which autonomic reactivity and associated visceral afference can modulate more rostral components of the system. The proposed model offers a more comprehensive framework for research on the neurobiology of anxiety and autonomic control.

Heart rate variability: origins, methods, and interpretive caveats

Components of heart rate variability have attracted considerable attention in psychology and medicine and have become important dependent measures in psychophysiology and behavioral medicine. Quantification and interpretation of heart rate variability, however, remain complex issues and are fraught with pitfalls. The present report (a) examines the physiological origins and mechanisms of heart rate variability, (b) considers quantitative approaches to measurement, and (c) highlights important caveats in the interpretation of heart rate variability. Summary guidelines for research in this area are outlined, and suggestions and prospects for future developments are considered.

Illusions, arithmetic, and the bidirectional modulation of vagal control of the heart

Behavioral contexts can evoke a variety of autonomic modes of response, characterized by reciprocal, coactive, or independent changes in the autonomic divisions. The present study investigated the modes of autonomic response to visual illusion and mental arithmetic tasks, by the use of noninvasive measures of sympathetic (pre-ejection period; PEP) and parasympathetic (respiratory sinus arrhythmia; RSA) cardiac control. As previously demonstrated, mental arithmetic was associated with a reciprocal pattern of sympathetic activation and vagal withdrawal. The illusion task, however, yielded a distinct mode of vagal activation in the absence of sympathetic change. Responses within tasks were reliable. In contrast to the general intertask consistency reported for stress tasks that yield similar autonomic modes of response, however, neither PEP nor RSA responses were correlated across the illusion and arithmetic tasks. This may be attributable to the dissimilar modes of autonomic control evoked by these tasks. The distinct modes of autonomic response to arithmetic and illusions emphasize the importance of a bivariate model of autonomic control, and may offer important experimental tools for psychophysiological studies of autonomic control.

Differential autonomic mechanisms underlying early morning and daytime transient myocardial ischaemia in patients with stable coronary artery disease

OBJECTIVES

To see whether autonomic regulatory mechanisms play a part in transient myocardial ischaemia in patients treated with beta blockers.

DESIGN

Prospective study.

SETTING

Outpatients' clinic.

PATIENTS

51 consecutive patients with angiographically documented coronary artery disease, stable angina, and transient myocardial ischaemia despite beta blockade.

INTERVENTIONS

24 hour ambulatory electrocardiographic monitoring for analysis of variability in ST depression and heart rate.

MAIN OUTCOME MEASURES

Numbers of episodes of ischaemia, with an ST depression of > or = 0.1 mV 80 ms after the J point that lasted > or = 60 s at an interval of > or = 60 s from a previous ischaemic episode. Heart rate at onset of ischaemia. Normalised spectral analysis of heart rate variability; ratio of low to high frequency power to assess the sympathovagal balance.

RESULTS

Despite treatment, 258 episodes of transient ischaemia were recorded. At heart rates at onset of ischaemia of < 70 beats per minute a high ratio of low to high frequency power accompanied the ischaemic events and was paralleled by a remarkably reduced high frequency power. The high ratio--that is, enhanced sympathetic tone during ischaemia--was mainly found in the early morning. By contrast, ischaemic episodes with heart rates at onset of > or = 70 beats per minute were not associated with significant changes in the parameters of autonomic function.

CONCLUSIONS

During beta blockade the residual transient ischaemia is associated with decreased variability in heart rate. In particular, in ischaemic episodes with a low heart rate at onset the neural regulation of the heart plays a part. Apparently, variability in heart rate is not sufficiently modified by beta blockers to prevent all ischaemia. The ischaemia related change in the autonomic nervous system during the early morning is in agreement with previous studies, showing increased cardiovascular risk at this time of the day.

Autonomic cardiac control. III. Psychological stress and cardiac response in autonomic space as revealed by pharmacological blockades

Behavioral contexts can evoke a variety of autonomic modes of response, characterized by reciprocal, coactive, or independent changes in the autonomic divisions. In the present study, we investigated the reactive autonomic control of the heart in response to psychological stressors, using quantitative methods for analyzing single and double autonomic blockades, and through the use of noninvasive indices based on heart period variability and systolic time intervals. Analysis of the effects of pharmacological blockades revealed an overall pattern of increased sympathetic and decreased parasympathetic control of the heart during speech stress, mental arithmetic, and a reaction-time task. Unlike the classical reciprocal sympathetic-parasympathetic response to orthostatic challenge, however, the responses of the autonomic branches to stress were uncorrelated. This reflected notable individual differences in the mode of autonomic response to stress, which had considerable stability across stress tasks. The putative noninvasive indices of sympathetic (preejection period) and parasympathetic (respiratory sinus arrhythmia) control changed in accord with the results of pharmacological blockades. Together, these results emphasize the substantial individual differences in the mode of autonomic response to stress, the advantages of a quantitative approach to analyzing blockade data, and the importance of validity estimates of blockade data.

Role of the central and arterial chemoreceptors in the response of gastric tone and motility to hypoxia, hypercapnia and hypocapnia in rats

The contribution of autonomic nerve activity to stomach tone and motility during central and arterial chemoreceptor excitation or inhibition was analyzed in urethane anesthetized, artificially ventilated rats. Systemic severe hypoxia at end-tidal O2 concentration (FETO2) 6% and systemic hypercapnia at end-tidal CO2 concentration (FETCO2) 6%, 8% and 10% applied for 1 min produced a significant depression in gastric tone and motility. Hypocapnia at 3% FETCO2 increased gastric tone and motility. Hypoxia co-activated both the sympathetic and the vagal efferent gastric nerve branches. Hypercapnia augmented only sympathetic gastric efferent nerve activity but not vagal efferent nerve activity. Hypocapnia slightly increased vagal nerve activity to the stomach. Bilateral denervation of the arterial chemoreceptors significantly attenuated the inhibitory gastric response to hypoxia. Similar attenuation of hypoxia-induced depression of gastric tone and motility was produced by bilateral gastric sympathectomy but not by vagotomy. In contrast, the inhibitory effect of severe hypercapnia and the facilitatory effect of hypocapnia upon gastric tone and motility were unaffected by arterial chemoreceptor denervation, by severance of gastric sympathetic branches or by gastric vagal denervation. Hyperoxia at 90% FETO2 had no effect on the gastric nerve activities, gastric tone or motility. It is concluded that in the rat hypoxia co-activates sympathetic and vagal efferent nerve activities to the stomach via an arterial chemoreceptor reflex, and that hypercapnia activates sympathetic gastric nerve activity via central chemoreceptors. Hypocapnia activates efferent vagal gastric nerve activity. All chemical stimuli except that of hyperoxia have a significant local effect on the gastric tone and motility.(ABSTRACT TRUNCATED AT 250 WORDS)