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Biomedical subjects

S W Porges

Publications and source records attributed to S W Porges.

At least 37 records · Page 2Linked to original sources
PubMed1997

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.

Animals↗
PubMed1997

Vagal regulation during bottle feeding in low-birthweight neonates: support for the gustatory-vagal hypothesis.

The gustatory-vagal hypothesis proposes that gustatory stimulation elicits a coordinated vagal response manifested as an increase in ingestive behaviors (e.g., sucking) and a decrease in nucleus ambiguus vagal tone measured by decreases in the amplitude of respiratory sinus arrhythmia (RSA). The current study tested the gustatory-vagal hypothesis in a bottle feeding paradigm with 29 clinically stable, high-risk, low-birthweight neonates. The amplitude of respiratory sinus arrhythmia (RSA) was collected before, during, and after bottle feeding. Consistent with the gustatory-vagal hypothesis, RSA decreased during bottle feeding. In a longitudinal subsample of subjects, the pattern of RSA changes during the feeding paradigm was stable across two test sessions.

Electrocardiography↗
PubMed1997

Vagal regulation of heart rate in the prediction of developmental outcome for very low birth weight preterm infants.

To investigate heart rate and respiratory sinus arrhythmia (RSA) as markers of developmental outcome, infant ECG and 3 year outcome were assessed in 41 very low birth weight (< 1,500 g) infants. Measures of mean heart rate and RSA, and the maturational shifts in their values from 33 to 35 weeks gestational age, were recorded. RSA measures predicted 3 year outcome beyond the effects of birth weight, medical risk, and socioeconomic status. Higher RSA was associated with better social skills, whereas greater RSA maturation was associated with better mental processing and gross motor skills. Lower heart rate was associated with better behavior regulation and social skills, whereas greater maturational decreases were associated with better gross motor skills. Dividing the sample into groups of infants with birth weights less than 1,000 g and those with birth weights over 1,000 g, RSA maturation emerged a strong predictor of mental processing, knowledge base, and gross motor skills in the former. A measure of joint maturation of RSA and heart rate was associated with better behavior regulation at 3 years, as measured by Child Behavior Checklist and Parenting Stress Index scores, for this group. The findings directly respond to the need for physiological variables in the prediction of outcome in high-risk infants.

Arousal↗
PubMed1996

Infant regulation of the vagal "brake" predicts child behavior problems: a psychobiological model of social behavior.

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.

Brain Stem↗
PubMed1996

Cardiac rhythm effects of .125-Hz paced breathing through a resistive load: implications for paced breathing therapy and the polyvagal theory.

This study examined the psychophysiological effects of slow-paced breathing while subjects breathed through external respiratory resistive loads. Twenty-four normal volunteers completed four 5-min trials of paced breathing (.125 Hz) through an inspiratory resistive wire mesh screen (0 to 25 cm H2O/L/s). Each trial was followed by a 5-min rest trial. There was evidence for hyperventilation and/or fatigue during paced breathing. Also, respiratory sinus arrhythmia (RSA) was elevated in the first minute of paced breathing, and then declined toward baseline. Heart period decreased during paced breathing trials, and fell significantly below baseline during rest periods. These data suggest decreased vagus nerve activity and/or sympathetic activation, following an initial increase in parasympathetic activity during paced breathing. They are not consistent with the use of .125-Hz paced breathing as a relaxation technique, particularly during respiratory resistive stress. Finally, although RSA and average heart period changed synchronously within paced breathing and rest conditions, they diverged in comparisons between pacing and rest. This dissociation suggests that different mechanisms mediate these two cardiac parameters. These data are consistent with Porges' theory that vagal influences on tonic heart rate are mediated by the combined effect of vagal projections from both the nucleus ambiguus and the dorsal motor nucleus, while RSA is mediated only through the nucleus ambiguus alone.

Adolescent↗
PubMed1996

Behavioral sleep states in very low birth weight preterm neonates: relation to neonatal health and vagal maturation.

Assessed the relation of behavioral codes of quiet versus active sleep state to neonatal health status in 62 very low birth weight preterm neonates. Sleep sessions (12 min) were coded for percentage time in active versus quiet sleep at 33, 34, and 35 weeks conceptional age. ECG was monitored during each sleep session to derive measures of heart rate, heart rate variability, and an index of cardiac vagal tone derived from respiratory sinus arrhythmia. Higher risk neonates spent more sleep session time in active sleep than healthier preterm neonates. Cardiac vagal tone showed a maturational change during the study weeks, whereas percentage of sampled sleep time in active sleep did not. Vagal maturation measured by age-related increases in the amplitude of respiratory sinus arrhythmia was associated with less active sleep overall, although weekly measures of respiratory sinus arrhythmia and sleep state were not related. Follow-up data on 30 of the neonates indicated that heart rate variability and cardiac vagal tone, but not sleep state measures, were related to better outcomes in mental processing, social skills, and motor skills, and to fewer behavior problems. Results are discussed in terms of the lack of coupling between behavioral and physiological components of preterm sleep states at this age as compared with that seen in full-term sleep states.

Female↗
PubMed1996

Role of aerobic capacity and body mass index in the age-associated decline in heart rate variability.

The extent to which age-associated changes in aerobic capacity and body composition modulate the age-associated decline in heart rate variability (HRV) is unknown. We therefore measured HRV, peak O2 consumption (VO2peak) during treadmill testing, and relative weight (body mass index; BMI) in 164 healthy normotensive adults (75 men, age 20-87 yr) from the Baltimore Longitudinal Study on Aging. Two components of HRV, respiratory sinus arrhythmia (RSA; 0.12-0.40 Hz) and 0.10-Hz variability (0.06-0.10 Hz), were extracted from 8-min electrocardiogram recordings in the supine, seated, and standing postures. RSA, 0.10-Hz variability, and VO2peak varied inversely with age; BMI was unrelated to age. Age contributed 15.5-21.1% independent variance to RSA and 13.2-17.3% independent variance to 0.10-Hz HRV. VO2peak did not contribute significantly to RSA or 0.10-Hz HRV beyond the effect of age in any posture. There were no consistent independent contributions of BMI to HRV. Thus, in this population-based sample, age-associated changes in aerobic capacity and relative body weight do not provide the primary explanation for the decline in HRV observed with advancing age.

Adult↗
PubMed1995

Cardiac vagal tone: a physiological index of stress.

Cardiac vagal tone is proposed as a novel index of stress and stress vulnerability in mammals. A model is described that emphasizes the role of the parasympathetic nervous system and particularly the vagus nerve in defining stress. The model details the importance of a branch of the vagus originating in the nucleus ambiguus. In mammals the nucleus ambiguus not only coordinates sucking, swallowing, and breathing, but it also regulates heart rate and vocalizations in response to stressors. In mammals it is possible, by quantifying the amplitude of respiratory sinus arrhythmia, to assess the tonic and phasic regulation of the vagal pathways originating in the nucleus ambiguus. Measurement of this component of vagal tone is proposed as a method to assess, on an individual basis, both stress and the vulnerability to stress.

Animals↗
PubMed1995

Orienting in a defensive world: mammalian modifications of our evolutionary heritage. A Polyvagal Theory.

The vagus, the 10th cranial nerve, contains pathways that contribute to the regulation of the internal viscera, including the heart. Vagal efferent fibers do not originate in a common brainstem structure. The Polyvagal Theory is introduced to explain the different functions of the two primary medullary source nuclei of the vagus: the nucleus ambiguus (NA) and the dorsal motor nucleus (DMNX). Although vagal pathways from both nuclei terminate on the sinoatrial node, it is argued that the fibers originating in NA are uniquely responsible for respiratory sinus arrhythmia (RSA). Divergent shifts in RSA and heart rate are explained by independent actions of DMNX and NA. The theory emphasizes a phylogenetic perspective and speculates that mammalian, but not reptilian, brainstem organization is characterized by a ventral vagal complex (including NA) related to processes associated with attention, motion, emotion, and communication. Various clinical disorders, such as sudden infant death syndrome and asthma, may be related to the competition between DMNX and NA.

Animals↗
PubMed1995

Frontal activation asymmetry and social competence at four years of age.

The pattern of frontal activation as measured by the ongoing electroencephalogram (EEG) may be a marker for individual differences in infant and adult disposition to respond with either positive or negative affect. We studied 48 4-year-old children who were first observed in same-sex quartets during free-play sessions, while making speeches, and during a ticket-sorting task. Social and interactive behaviors were coded from these sessions. Each child was subsequently seen 2 weeks later when EEG was recorded while the child attended to a visual stimulus. The pattern of EEG activation computed from the session was significantly related to the child's behavior in the quartet session. Children who displayed social competence (high degree of social initiations and positive affect) exhibited greater relative left frontal activation, while children who displayed social withdrawal (isolated, onlooking, and unoccupied behavior) during the play session exhibited greater relative right frontal activation. Differences among children in frontal asymmetry were a function of power in the left frontal region. These EEG/behavior findings suggest that resting frontal asymmetry may be a marker for certain temperamental dispositions.

Affect↗
PubMed1994

Cardiac vagal tone: stability and relation to difficultness in infants and 3-year-olds.

Psychophysiological studies of infants have found a relation between behavioral reactivity and indices of autonomic state. The relation between behavioral reactivity, assessed via maternal report, and autonomic state, assessed via cardiac vagal tone in 9-month-old infants was examined. Cardiac vagal tone was quantified by measuring the amplitude of respiratory sinus arrhythmia. High cardiac vagal tone was associated with greater behavioral reactivity, resulting in maternal reports of more difficult temperament. Stability of the two measures, cardiac vagal tone and difficult temperament, from 9 months to 3 years of age was demonstrated. In addition, 9-month cardiac vagal tone, independent of 9-month temperament, was related to 3-year difficultness with higher 9-month cardiac vagal tone being related to less-difficult 3-year behavior.

Arousal↗
PubMed1994

Cardiac vagal tone and sustained attention in school-age children.

Three hypotheses tested relationships between cardiac responses mediated via the vagus and sustained attention in a population of normal school-age children. These hypotheses addressed the theoretical relationships among resting cardiac vagal tone (using the Porges estimate of respiratory sinus arrhythmia, V), performance measures of sustained attention, and cardiac reactivity during sustained attention. Thirty-two fourth and fifth grade children performed a continuous performance task while their electrocardiograms were monitored. Children with higher resting levels of V performed better on the first 3-min block of the continuous performance task. Additionally, levels of V were significantly reduced across the blocks of the 9-min task for all children. No relationships were found between resting levels of V and change in either V or heart period during task performance. These findings support two of the three hypotheses proposed by Porges regarding individual differences in cardiac vagal tone and sustained attention.

Aging↗
PubMed1994

Vagal tone and the physiological regulation of emotion.

On the basis of current knowledge of neuroanatomy and our previous research with cardiac vagal tone, we have proposed the vagal circuit of emotion regulation. The vagal circuit of emotion regulation incorporates lateral brain function with the regulation of the peripheral autonomic nervous system in the expression of emotion. The vagus and the vagal circuit do not function independently of other neurophysiological and neuroendocrine systems. Research on brain activity (see Dawson, in this volume; Fox, in this volume) and research on adrenocortical activity (see Stansbury & Gunnar, in this volume) demonstrate that EEG and cortisol are related to emotion states and to individual differences similar to those that we have investigated. The vagal circuit emphasizes not only the vagus but also the lateralization of specific brain structures in emotion regulation. The emphasis of the vagal circuit on right-brain-stem structures stimulates several testable hypotheses regarding the function of specific structures in the right brain in emotion regulation. These speculations are consistent with other reports (see Dawson, in this volume; Fox, in this volume) describing asymmetrical EEG activity during expressed emotions. Moreover, the vagal circuit does not exist independently of the brain structures and peptide systems regulating cortisol (see Stansbury & Gunnar, in this volume). Areas in the brain stem regulating vagal activity are also sensitive to the peptides that regulate cortisol (e.g., vasopressin and corticotropin-releasing hormone). In this essay, we have provided information regarding the relation between vagal tone and emotion regulation. A review of research indicates that baseline levels of cardiac vagal tone and vagal tone reactivity abilities are associated with behavioral measures of reactivity, the expression of emotion, and self-regulation skills. Thus, we propose that cardiac vagal tone can serve as an index of emotion regulation. Historically, the vagus and other components of the parasympathetic nervous system have not been incorporated in theories of emotion. Recent developments in methodology have enabled us to define and accurately quantify cardiac vagal tone. Theories relating the parasympathetic nervous system to the expression and regulation of emotion are now being tested in several laboratories.

Affect↗
PubMed1993

Hypnotic susceptibility, mood state, and cardiovascular reactivity.

In this study we explored the relationship between hypnotic susceptibility measured with the Harvard Group Scale of Hypnotic Susceptibility (HGSHS) and cardiovascular parameters. After assessing their degree of hypnotic susceptibility, we induced 21 female students into happy mood states and into sad mood states. During the mood state induction we monitored blood pressure, heart rate, and cardiac vagal tone continuously. The study demonstrated a strong relationship between hypnotic susceptibility and both cardiac vagal tone and heart rate reactivity. Subjects with lower heart rate and greater vagal tone during baseline and greater heart rate increases during mood induction were more susceptible to hypnosis. Multiple regression analyses indicated that approximately 40% of the individual difference variance of hypnotic susceptibility was accounted for by baseline cardiac vagal tone and heart rate reactivity during mood state. The data demonstrate that autonomic tone, assessed by cardiac vagal tone and heart rate reactivity, are related to hypnotic susceptibility as measured by the HGSHS.

Adult↗
PubMed1993

Data-dependent filter characteristics of peak-valley respiratory sinus arrhythmia estimation: a cautionary note.

Filter characteristics of the peak-valley respiratory sinus arrhythmia estimation method are described. To identify filter characteristics of this method, models were generated that combined signals of different frequencies with trends of varying slopes. These models simulate the influence of trend and changing respiratory frequency on the accuracy of peak-valley estimates. The transfer function of the peak-valley method, unlike that of other time domain filters, is not solely dependent upon signal frequency. Two factors interact to determine the relative accuracy of the peak-valley method: (a) slope of the signal component and (b) slope of the underlying trend. Combinations of these factors may result in significant distortion to the input signal. The direction of error is a function of the direction of the trend (i.e., overestimation with deceleration and underestimation with acceleration). In many situations when respiratory sinus arrhythmia amplitude is low in special populations (e.g., cardiovascular disorders, high-risk infants, or human fetuses) or under conditions that greatly reduce respiratory sinus arrhythmia amplitude (e.g., exercise, drugs, pharmacological manipulations), use of the peak-valley method may result in significant measurement error. The use of this method to evaluate respiratory sinus arrhythmia over short epochs (i.e., less than 2 min) or to quantify changes in respiratory sinus arrhythmia due to discrete stimulation (e.g., breath by breath) may result in inconsistent measurement error. Recommendations are made for detrending heart rate data prior to application of the peak-valley method.

Arrhythmia, Sinus↗
PubMed1992

Effects of alprazolam and imipramine on parasympathetic cardiac control in patients with generalized anxiety disorder.

A noninvasive measure was used to assess the effects of alprazolam, imipramine and placebo on parasympathetic (vagal) cardiac control following 6-weeks of medication in patients with generalized anxiety disorder. Flexible dosage at therapeutic levels resulted in increased heart rate and blood pressure and in decreased cardiac vagal control in patients receiving imipramine but not alprazolam or placebo. About 50% of the variance in heart rate changes and changes in mean arterial blood pressure following treatment with imipramine could be accounted for by changes in cardiac vagal control. Decreased cardiac vagal control can now be added to the list of cardiovascular changes seen following several weeks of treatment with imipramine.

Adult↗
PubMed1992

Research methods for measurement of heart rate and respiration.

Strategies for heart rate and respiration quantification are dependent upon a knowledge of physiology and statistics. To develop appropriate and sensitive psychophysiological measures, it is necessary to understand the neural control of the autonomic nervous system and the statistical characteristics of physiological data. Moreover, it is proposed that inferences derived from physiological measures are dependent upon a statistical interaction between the characteristics of the physiological data and the measurement techniques. The steps required to analyze heart rate and respiration data are presented, ranging from data acquisition and editing to data analysis and physiological inference. A variety of techniques are described and contrasted with recommendations for future research.

Arousal↗