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Biomedical subjects

S W Porges

Publications and source records attributed to S W Porges.

At least 19 recordsLinked to original sources
PubMed2001

Vagal modulation of responses to mental challenge in posttraumatic stress disorder.

BACKGROUND: Studies of the autonomic nervous system in posttraumatic stress syndrome (PTSD) have focused on the sympathetic modulation of arousal and have neglected the parasympathetic contribution. This study addresses the parasympathetic control of heart rate in individuals who have survived traumatic events. METHODS: Twenty-nine survivors, 14 with current PTSD and 15 without, participated in the study. The groups were comparable with regard to age, type of trauma, time since the latest traumatic event, and lifetime exposure to traumatic events. Electrocardiograms were recorded during rest and an arithmetic task. Heart period, respiratory sinus arrhythmia (RSA), and the amplitude of the Traube-Hering-Mayer wave were quantified. RESULTS: The groups did not differ on resting measures. During the arithmetic task, the past trauma group showed a significant increase in RSA (p <.007), whereas the PTSD group did not. In the past trauma group only, RSA and heart period were highly correlated (r =.75), thereby suggesting that the response to challenge was under vagal control. CONCLUSIONS: Trauma survivors who develop PTSD differ from those who do not in the extent to which their heart rate response to challenge is controlled by vagal activity. Responses to challenge in PTSD may be mediated by nonvagal, possibly sympathetic mechanisms.

Adult↗
PubMed2001

The polyvagal theory: phylogenetic substrates of a social nervous system.

The evolution of the autonomic nervous system provides an organizing principle to interpret the adaptive significance of physiological responses in promoting social behavior. According to the polyvagal theory, the well-documented phylogenetic shift in neural regulation of the autonomic nervous system passes through three global stages, each with an associated behavioral strategy. The first stage is characterized by a primitive unmyelinated visceral vagus that fosters digestion and responds to threat by depressing metabolic activity. Behaviorally, the first stage is associated with immobilization behaviors. The second stage is characterized by the sympathetic nervous system that is capable of increasing metabolic output and inhibiting the visceral vagus to foster mobilization behaviors necessary for 'fight or flight'. The third stage, unique to mammals, is characterized by a myelinated vagus that can rapidly regulate cardiac output to foster engagement and disengagement with the environment. The mammalian vagus is neuroanatomically linked to the cranial nerves that regulate social engagement via facial expression and vocalization. As the autonomic nervous system changed through the process of evolution, so did the interplay between the autonomic nervous system and the other physiological systems that respond to stress, including the cortex, the hypothalamic-pituitary-adrenal axis, the neuropeptides of oxytocin and vasopressin, and the immune system. From this phylogenetic orientation, the polyvagal theory proposes a biological basis for social behavior and an intervention strategy to enhance positive social behavior.

Animals↗
PubMed2001

Neonatal cardiac vagal tone and school-age developmental outcome in very low birth weight infants.

Twenty very low birth weight (VLBW) children participated in a longitudinal follow-up study designed to explore the relation between neonatal physiological measures and school-age (6-9 years) outcome measures. Neonatal measures of mean heart period and cardiac vagal tone (respiratory sinus arrhythmia, RSA) were derived from weekly recordings at 33, 34, and 35 weeks gestational age. An RSA Maturation measure was calculated across the 3-week period to assess functional changes in vagal regulation of the heart during a period in which there is enhanced myelination of the vagus. In addition, the relation of neonatal risk measures (low birth weight, low socioeconomic status, high medical risk) and preschool measures (behavior, cognitive abilities) to school-age outcome measures was examined. As expected, school-age measures were closely related to preschool measures within the same domain. Neonatal risk measures were not related to school-age outcome measures. Of the neonatal physiological measures, RSA maturation was correlated with a single school-age measure, social competence as measured by the Child Behavior Checklist (Achenbach, 1988). Partial correlation and multiple regression analyses were used to further explore the relationship between neonatal RSA maturation and school-age social competence. Results support the hypothesis that early central nervous system self-regulatory abilities, as assessed by RSA measures, are predictive of later complex behaviors.

Age Factors↗
PubMed2000

Respiratory sinus arrhythmia during feeding: a measure of vagal regulation of metabolism, ingestion, and digestion in preterm infants.

Respiratory sinus arrhythmia (RSA), a non-invasive indicator of vagal regulation of the heart, and heart period (HP) were monitored before, during, and after oral or gastric-tube bolus feedings in 32 preterm infants. Group 1 infants (n=15) were < or =30 weeks gestational age (GA) at birth (mean 28.3 weeks) and group 2 infants (n=17) were > or =31 weeks GA at birth (mean=33.2 weeks). Mean postmenstrual ages at the time of study were 33.5 +/- 2.3 (SD) weeks in group 1 and 33.9 +/- 1.6 (SD) weeks in group 2. RSA and HP decreased in both groups during feeding. However, postfeeding RSA and HP increased toward prefeed levels only for group 2 infants. In addition, RSA and HP changes during feeding were correlated only for group 2 infants. The results suggest that the preterm infant may experience a maturational lag in vagal function and in the influence of vagal activity on metabolic mechanisms (i.e. heart rate) related to ingestive needs. This maturational lag may contribute to continued feeding difficulties and may be a measurable marker of subtle neurodevelopmental problems.

Analysis of Variance↗
PubMed2000

Therapeutic effects of imipramine are counteracted by its metabolite, desipramine, in patients with generalized anxiety disorder.

Imipramine has been shown to reduce anxiety in patients with generalized anxiety disorder (GAD). However, some properties of imipramine may diminish or counteract its anxiolytic effects. The authors previously found that the greater the reduction in cardiac vagal control after 6 weeks of imipramine treatment, the smaller the improvement in anxiety-related symptoms. The purpose of this study was to determine whether the authors' previous findings were replicable and to gather information on the plasma levels of imipramine, desipramine (the major metabolite of imipramine), and anticholinergic levels. Fourteen patients with GAD were administered imipramine for 6 weeks. Their scores from self-administered and investigator-administered rating scales were obtained before and after the treatment, and the changes in these scores were contrasted with the changes in cardiac vagal tone, along with the absolute plasma levels of imipramine, desipramine, and anticholinergic activity at the end of week 6. The authors observed a greater improvement in symptoms of anxiety in those who showed the smallest decreases in cardiac vagal tone and in those who showed the smallest increases in desipramine and anticholinergic plasma levels. Moreover, strong relationships were observed between desipramine and anticholinergic levels. These results demonstrate that imipramine not only has therapeutic effects, but it may also have properties that result in physiologic states that counteract its therapeutic effects. Future research should investigate the direct anticholinergic effects of desipramine and determine whether there is a parallel between the anticholinergic effects and the clinical outcome of other pharmacologic treatments, including antidepressants with predominantly norepinephrine or serotonin reuptake inhibitory properties.

Adrenergic Uptake Inhibitors↗
PubMed2000

Vagal and cardiac reactivity to psychological stressors in trained and untrained men.

PURPOSE: The aim of this study was to determine whether higher aerobic fitness is associated with enhanced vagal influences on the myocardium, resulting in moderation of chronotropic cardiac activity during psychological stress and recovery. METHOD: Heart period (HP) and respiratory sinus arrhythmia (RSA) were obtained from 10 aerobically trained (AT) and 10 untrained (UT) college-aged men at rest and during three contiguous psychological challenges and 3 min of recovery. Ratings of perceived stress were obtained at the end of the rest period, at the midpoint of each stressor, and at 30 s into recovery. Time series methods were used to quantify RSA from the beat-to-beat HP series. Responsivity was assessed both in terms of absolute levels of activity and phasic changes in activity (task or recovery minus baseline). RESULTS: Both groups reported similar levels of subjective stress throughout the experiment. The AT exhibited longer HP at rest and during psychological stress and recovery than did the UT. However, the groups did not differ on RSA at rest or during psychological stress and recovery, nor did they differ on phasic changes in RSA or HP during stress or recovery. Additionally, aerobic capacity was not correlated with absolute levels or phasic changes in RSA during psychological challenge for either group and, except in Min 2 for the UT, similar results were obtained for recovery. CONCLUSIONS: The results supported the hypothesis that, among young men, higher aerobic fitness is associated with longer HP at rest and during psychological stress and recovery. However, the lower cardiac chronotropic activation observed among the AT relative to the UT was not paralleled by a group difference in the amplitude of RSA. These results suggest that the group difference in HP was not mediated directly by the vagal mechanisms manifested in the amplitude of RSA.

Adult↗
PubMed2000

Evaluating group distributional characteristics: why psychophysiologists should be interested in qualitative departures from the normal distribution.

Real data often do not approximate the normal distribution. Under nonnormal conditions, psycho-physiologists who use parametric statistics may be testing with inadequate power and/or testing a measure of location (i.e., the mean) that does not represent the desired portion of the distribution for statistical comparison. The purpose of this paper is: first, to provide psycho-physiologists with a method to investigate group distributional characteristics; second, to evaluate the distributional characteristics of heart period and respiratory sinus arrhythmia in human adults and newborns; third, to demonstrate the increased statistical power that can accompany the selection of an alternative statistical analysis for nonnormal data. Suggestions are provided on how to analyze nonnormal data.

Adult↗
PubMed1999

Sleep state and vagal regulation of heart period patterns in the human newborn: an extension of the polyvagal theory.

The influence of sleep state (i.e., active and quiet) on heart period, heart period variability, respiratory sinus arrhythmia (RSA), and the coupling between RSA and heart period was evaluated in 24 healthy full-term newborns. Electrocardiogram (ECG) data were collected, and sleep state was coded 1 hr after feeding until at least 10 min of data were collected in states of active and quiet sleep. ECG data were analyzed for the first five continuous minutes of each sleep state. Relative to active sleep, quiet sleep was associated with significantly higher amplitude RSA, lower heart period variability, and longer heart periods. Because RSA amplitude reflects the functional output of vagal pathways originating in the nucleus ambiguus, it was hypothesized that sleep state would influence how these vagal pathways regulate instantaneous changes in heart period. A new method, evaluating the instantaneous coupling of RSA and heart period, demonstrated that coupling was significantly greater during active sleep. The neurophysiological explanation extends the polyvagal theory to include potential cortical-brain stem connections.

Arrhythmia, Sinus↗
PubMed1999

Effect of alcohol on vagal regulation of cardiovascular function: contributions of the polyvagal theory to the psychophysiology of alcohol.

Research was conducted to evaluate the influence of acute alcohol consumption on vagal regulation of heart rate. Nine men with histories of polydrug use participated in this residential study. On 5 separate days, they drank liquids consisting of cold water (on 2 days), a moderate dose of alcohol (0.64 g/kg), a high dose of alcohol (1.12 g/kg), and a placebo. Continuous recordings of heart period were quantified to produce 3 measures of heart rate variability, reflecting the amplitude of 3 neurophysiologically mediated rhythms. Heart period, respiratory rhythm (i.e., respiratory sinus arrhythmia [RSA]), and the 0.064-0.10-Hz vasomotor rhythm were significantly lower during the high alcohol dose condition, relative to the placebo and water conditions. Because the neural regulation of the heart by the vagus contributes to these variables, these findings suggest that alcohol reduces cardiac vagal tone. In support of this explanation, alcohol also decreased the coupling between changes in heart period and changes in RSA. This study demonstrated that alcohol produces a dysregulated state in which heart rate is relatively uncoupled from vagal activity.

Adult↗
PubMed1999

A neural explanation of fetal heart rate patterns: A test of the polyvagal theory.

The current study applies a neurophysiological model based on the Polyvagal Theory (Porges, 1995) to interpret fetal heart rate patterns. Beat-to-beat heart rate data from 7 fetuses monitored during the first and second stages of labor were analyzed. Transitory heart rate accelerations and reduced beat-to-beat variability reliably preceded heart rate decelerations. The data are interpreted within the context of the Polyvagal Theory, which provides a plausible explanation of the neurophysiological mechanisms that mediate fetal heart rate decelerations. Specifically, it is proposed that both the transitory heart rate accelerations and the depression of the respiratory rhythm in the beat-to-beat heart rate pattern reflect a withdrawal of the vagal tone determined by myelinated vagal pathways originating in the nucleus ambiguus. Functionally, withdrawal of vagal tone originating in the nucleus ambiguus results in the cardiac pacemaker becoming vulnerable to sympathetic influences and to the more-primitive unmyelinated vagal pathways originating in the dorsal motor nucleus of the vagus, which may contribute to clinically relevant bradycardia.

Arrhythmia, Sinus↗
PubMed1998

Love: an emergent property of the mammalian autonomic nervous system.

The evolution of the autonomic nervous system provides an organizing principle to interpret the adaptive significance of mammalian affective processes including courting, sexual arousal, copulation, and the establishment of enduring social bonds. According to the Polyvagal Theory (Porges, 1995, 1996, 1997), the well-documented phylogenetic shift in the neural regulation of the autonomic nervous system passes through three stages, each with an associated behavioral strategy. The first stage is characterized by a primitive unmyelinated visceral vagus that fosters digestion and responds to threat by depressing metabolic activity. Behaviorally, the first stage is associated with immobilization behaviors. The second stage is characterized by the sympathetic nervous system that is capable of increasing metabolic output and inhibiting the visceral vagus to foster mobilization behaviors necessary for 'fight or flight'. The third stage, unique to mammals, is characterized by a myelinated vagus that can rapidly regulate cardiac output to foster engagement and disengagement with the environment. The mammalian vagus is neuroanatomically linked to the cranial nerves that regulate social engagement via facial expression and vocalization. The Polyvagal Theory provides neurobiological explanations for two dimensions of intimacy: courting and the establishment of enduring pair-bonds. Courting is dependent upon the social engagement strategies associated with the mammalian vagus. The establishment of enduring pair-bonds is dependent upon a co-opting of the visceral vagus from an immobilization system associated with fear and avoidance to an immobilization system associated with safety and trust. The theory proposes that the phylogenetic development of the mammalian vagus is paralleled by a specialized communication, via oxytocin and vasopressin, between the hypothalamus and the medullary source nuclei of the viscera vagus, which facilitates sexual arousal, copulation, and the development of enduring pair-bonds.

Animals↗
PubMed1998

A psychophysiological investigation of the effects of driving longer-combination vehicles.

Fatigue contributes to driving-related accidents and fatalities. Cardiovascular measures such as heart rate and heart rate variability may serve as early indicators of fatigue. In the current investigation, 24 professional truck drivers drove three truck configurations: single trailer, triple trailer A-dolly, and triple trailer C-dolly on a standard route that lasted between 8 and 10 h. During the driving session, continuous measures of heart rate were quantified on-line. In addition to heart rate, two measures of heart rate variability (i.e. respiratory sinus arrhythmia and the Traube-Hering-Mayer wave or 0.1 Hz oscillation) were derived from the beat-to-beat heart rate. Independent of configuration, heart rate increased and the measures of heart rate variability decreased during the driving route. Only heart rate statistically differed among the configurations. Since heart rate is physiologically linked to metabolic output, the results suggest that the observed effect may be due to the physical demands required to drive each truck configuration. In support of this conclusion, the heart rate effect was consistent with the subjective report of task demand. The slowest heart rates were observed while driving the least demanding configuration (i.e. single trailer). The fastest heart rates were observed while driving the most demanding configuration (i.e. triple trailer A-dolly).

Adult↗
PubMed1998

Respiratory sinus arrhythmia during exercise in aerobically trained and untrained men.

Respiratory sinus arrhythmia (RSA) was examined in aerobically trained (AT) and untrained (NT) college-aged males during 12 periods consisting of a 3-min sitting baseline, six common 3-min absolute exercise stages, and five 3-min recovery stages that followed voluntary exhaustion to determine the relationship of work and training status to parasympathetic influence upon the heart. RSA systematically decreased during absolute exercise, was observed at heart rates (HR) above 100 beats x min(-1), and progressively increased during recovery. Additionally, independent of work stages, comparative regression analyses were conducted for both the exercise and recovery phases, separately, in which HR was regressed on RSA, as well as RSA on % VO2max, to contrast the obtained relationships for the AT and NT. No differences were revealed as a function of endurance training status as the slopes and intercepts obtained for the two groups from each of these analyses were similar. The within-subject correlations between RSA and % VO2max, calculated for each of the individuals across all 12 periods, were consistently negative. Between-subjects correlations of RSA with RR and tidal volume were predominantly nonsignificant, indicating that RSA, as measured here, is independent of individual differences in ventilatory activity and, as such, can be compared between groups during exercise. The findings demonstrate that RSA is detectable during both exercise and recovery, even at HR beyond 100 beats x min(-1), and reveals a similar relationship to HR and metabolic state in both aerobically trained and untrained populations.

Adult↗
PubMed1998

Infant temperament and cardiac vagal tone: assessments at twelve weeks of age.

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.

Arousal↗
PubMed1997

Motivation, sustained attention, and autonomic regulation in school-age boys exposed in utero to opiates and alcohol.

The effects of incentive on sustained attention and autonomic regulation among boys exposed in utero to opiates were studied. Respiratory sinus arrhythmia (RSA), an indicator of autonomic regulation, was quantified during sustained attention in 3 groups of 7- to 12-year-old boys. RSA is a component of heart rate variability controlled by cortical influences and affected by changes in demand for attention. The Gordon Diagnostic System-Distractibility Task was performed with and without monetary reward. A cartoon task and a video game were used as measures of interest. Although opiate-exposed boys did not differ in performance as a function of incentive or interest, they had a tendency to perform more poorly overall across tasks. Alcohol exposure rather than opiate exposure covaried with autonomic regulation, with greater RSA decreases being associated with more alcohol exposure. Post hoc analyses revealed that the alcohol- and opiate-exposed boys responded with these hyperreactive RSA changes along with poorer performance.

Adult↗
PubMed1997

Inferential and descriptive influences on measures of respiratory sinus arrhythmia: sampling rate, R-wave trigger accuracy, and variance estimates.

The use of respiratory sinus arrhythmia (RSA) is dependent on several quantification factors. The statistical consequences of sampling rate, R-wave trigger accuracy, and the data structure of RSA estimates were evaluated via simulations and simulated modifications. Simulations demonstrated that sampling rate determined the amplitude of the smallest oscillation that could be accurately described. When the amplitude of the oscillation was smaller in milliseconds than the sampling interval, all smaller oscillations, regardless of amplitude, were indiscriminately assigned a default value defined as 50% of the sampling interval. Also, reduced R-wave peak detection accuracy was demonstrated to influence statistical analyses. The distributional characteristics of several common methods of structuring RSA estimates were investigated, and results indicated that several methods results in asymmetrical distributions. We recommend using rapid sampling rates (i.e., 1 kHz), accurate R-wave peak detectors, and avoiding statistical trouble.

Adolescent↗