Stephen W. Porges

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.

The Polyvagal Theory: phylogenetic contributions to social behavior:

The scientific legacy of Paul MacLean provides important insights into the neural substrate of adaptive social behavior in mammals. Through his research and visionary conceptualizations, current investigators can legitimately study social behavior from a neurobiological perspective. His research and writings provided three important contributions. First, he emphasized the importance of evolution as an organizing principle that shaped both the structure of the nervous system and the adaptive social behavior. Second, by defining the limbic system, he legitimized the biological perspective in the study of emotion. Third, he recognized the important role of the vagal afferents in the regulation of higher brain structures. The paper will focus on the Polyvagal Theory. The Polyvagal Theory is a new conceptualization of the role of vagus and employs several features that MacLean emphasized including the importance of evolution, limbic structures and vagal afferents. The Polyvagal Theory builds on these early findings by MacLean and focuses on the link between phylogenetic changes in the autonomic nervous system and social behavior. By focusing on the phylogenetic changes in the structure of the vagus and the role that the vagus plays in the neural regulation of visceral state, new insights regarding social behavior emerge. Moreover, by articulating the phylogenetically organized hierarchy of neural circuits, insights into benefits of social behavior become evident as do an understanding of the behavioral and physiological features associated with stress and psychiatric disorders.

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.

Emotion Recognition in Children with Autism Spectrum Disorders: Relations to Eye Gaze and Autonomic State.

Respiratory Sinus Arrhythmia (RSA), heart rate, and accuracy and latency of emotion recognition were evaluated in children with autism spectrum disorders (ASD) and typically developing children while viewing videos of faces slowly transitioning from a neutral expression to one of six basic emotions (e.g., anger, disgust, fear, happiness, sadness, and surprise). Children with ASD were slower in emotion recognition and selectively made more errors in detecting anger. ASD children had lower amplitude RSA and faster heart rate. Within the ASD group, children with higher amplitude RSA recognized emotions faster. Less severe ASD symptoms and increased gaze to the eye region in children with ASD were related to more accurate emotion recognition.

Social Engagement and Attachment

Abstract: This article focuses on the importance of social engagement and the behavioral and neurophysiological mechanisms that allow individuals to reduce psychological and physical distance. A model of social engagement derived from the Polyvagal Theory is presented. The model emphasizes phylogeny as an organizing principle and includes the following points: (1) there are well‐defined neural circuits to support social engagement behaviors and the defensive strategies of fight, flight, and freeze; (2) these neural circuits form a phylogenetically organized hierarchy; (3) without being dependent on conscious awareness, the nervous system evaluates risk in the environment and regulates the expression of adaptive behavior to match the neuroception of a safe, dangerous, or life‐threatening environment; (4) social engagement behaviors and the benefits of the physiological states associated with social support require a neuroception of safety; (5) social behaviors associated with nursing, reproduction, and the formation of strong pair bonds require immobilization without fear; and (6) immobilization without fear is mediated by a co‐opting of the neural circuit regulating defensive freezing behaviors through the involvement of oxytocin, a neuropeptide in mammals involved in the formation of social bonds. The model provides a phylogenetic interpretation of the neural mechanisms mediating the behavioral and physiological features associated with stress and several psychiatric disorders.

Oxytocin, vasopressin and sociality

The neurobiology of social behaviour is interwoven with autonomic, endocrine and other homoeostatic processes responsible for the adaptive functions of reproduction and survival. Young mammals are dependent on their mothers for nourishment, and the interaction between the mother and infant may be a physiological and neuroendocrine prototype for mammalian sociality. Although these adaptive functions of the mother-infant social behavioural dyad are obvious, adult social interactions, including social bonds, also are important to health and survival. Two neuropeptides, oxytocin (OXT) and arginine vasopressin (AVP), have been repeatedly implicated in mammalian social behaviours and emotional states that support sociality. Although best known for their roles in reproduction and homoeostasis, these peptides play a central role in the activation and expression of social behaviours and emotional states. Recent studies from our work with the prairie vole (Microtus ochrogaster), reviewed here, reveal a role for both OXT and AVP in behavioural and endocrine changes during social interactions, and also changes that are associated with the absence of social interactions (i.e. social isolation).

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.

Emotion: an evolutionary by-product of the neural regulation of the autonomic nervous system.

A new theory, the polyvagal theory of emotion, is presented which links the evolution of the autonomic nervous system to affective experience, emotional expression, vocal communication, and contingent social behavior. The polyvagal theory is derived from the well-documented phylogenetic shift in the neural regulation of the autonomic nervous system that expands the capacity of the organism to control metabolic output. The theory emphasizes the phylogenetic dependence of the structure and function of the vagus, the primary nerve of the parasympathetic nervous system. Three phylogenetic stages of neural development are described. The first stage is characterized by a primitive unmyelinated vegetative vagal system that fosters digestion and responds to novelty or threat by reducing cardiac output to protect metabolic resources. Behaviorally, this first stage is associated with immobilization behaviors. The second stage is characterized by a spinal sympathetic nervous system that can increase metabolic output and inhibit the primitive vagal system’s influence on the gut to foster mobilization behaviors necessary for “fight or flight.” The third stage, which is unique to mammals, is characterized by a myelinated vagal system that can rapidly regulate cardiac output to foster engagement and disengagement with the environment. The myelinated vagus originates in a brainstem area that evolved from the primitive gill arches and in mammals controls facial expression, sucking, swallowing, breathing, and vocalization. It is hypothesized that the mammalian vagal system fosters early mother-infant interactions and serves as the substrate for the development of complex social behaviors. In addition, the mammalian vagal system has an inhibitory effect on sympathetic pathways to the heart and thus promotes calm behavior and prosocial behavior. The polyvagal theory of emotion proposes that the evolution of the autonomic nervous system provides the organizing principle to interpret the adaptive significance of affective processes. The theory proposes that the evolution of the mammalian autonomic nervous system, and specifically the brainstem regulatory centers of the vagus and other related cranial nerves, provides substrates for emotional experiences and affective processes that are necessary for social behavior in mammals. In this context, the evolution of the nervous system limits or expands the ability to express

The polyvagal theory: new insights into adaptive reactions of the autonomic nervous system.

The polyvagal theory describes an autonomic nervous system that is influenced by the central nervous system, sensitive to afferent influences, characterized by an adaptive reactivity dependent on the phylogeny of the neural circuits, and interactive with source nuclei in the brainstem regulating the striated muscles of the face and head. The theory is dependent on accumulated knowledge describing the phylogenetic transitions in the vertebrate autonomic nervous system. Its specific focus is on the phylogenetic shift between reptiles and mammals that resulted in specific changes to the vagal pathways regulating the heart. As the source nuclei of the primary vagal efferent pathways regulating the heart shifted from the dorsal motor nucleus of the vagus in reptiles to the nucleus ambiguus in mammals, a face–heart connection evolved with emergent properties of a social engagement system that would enable social interactions to regulate visceral state.

Vagal tone: An autonomic mediator of affect

The autonomic nervous system and theories of emotion Overview Descriptions of emotion frequently include both a physiological and a facial expressive component. The physiological component has been described as changes in the peripheral autonomic nervous system often characterized by increased sweating, throbbing of the heart, pupillary dilation, facial flush, and gastric motility. These physiological responses have been hypothesized as either a necessary mediating mechanism or a peripheral correlate of the emotional experience (Cannon, 1927; James, 1884). Moreover, there is renewed speculation that some physiological signatures are associated with specific emotional states (e.g., Ekman, Levenson, & Friesen, 1983). In contrast with the research that has eloquently described detailed facial patterns and the social contexts associated with specific emotions, the role of physiology in the development of expressivity and the regulation of affect has not been adequately investigated. Although in the temperament literature a physiological substrate is commonly assumed to be related to the regulation of affect (e.g., Bates, Freeland, & Lounsbury, 1979; Rothbart & Derryberry, 1981), physiological measures are seldom quantified. Moreover, physiological constructs rarely motivate this area of research or provide insight into individual variations in the regulation and expression of affect.