|Dr. Stephen Porges is a professor of psychiatry at the University of North Carolina. He is professor emeritus of psychiatry at the University of Illinois at Chicago, where he directed the Brain-Body Center, and professor emeritus at the University of Maryland, where served as chair of the Department of Human Development and director of the Institute for Child Study. He was president of the Society for Psychophysiological Research and the Federation of Behavioral, Psychological, and Cognitive Sciences. He is a recipient of a National Institute of Mental Health Research Scientist Development Award. He has published more than 200 peer-reviewed scientific papers across several disciplines. In 1994, he proposed the Polyvagal Theory, a theory that links the evolution of the mammalian autonomic nervous system to social behavior. The theory has stimulated research and treatments that emphasize the importance of physiological state and behavioral regulation in the expression of several psychiatric disorders and provides a theoretical perspective to study and to treat stress and trauma. He is the author of The Polyvagal Theory: Neurophysiological Foundations of Emotions, Attachment, Communication, and Self-Regulation (Norton, 2011) and is currently writing Clinical Applications of the Polyvagal Theory: The Transformative Power of Feeling Safe (Norton, 2014).|
The Polyvagal Theory describes the role physiological state has in facilitating the expression of different classes of behavior. Applying the theory to behavior modification protocols leads to a refinement in the historical S-O-R model in which the state of the organism (O), now indexed by autonomic state, influences the accessibility of classes of behavior to stimulus control. Polyvagal Theory, based on evolutionary biology and comparative neurophysiology, identifies autonomic states that facilitate or impede the expression of specific classes of behavior. The theory identifies three stages of phylogenetic development that are characterized by parallel changes in behavioral repertoire and neural regulation of the autonomic nervous system: 1) an ancient autonomic system (i.e., unmyelinated "vagal" pathways) shared with most vertebrates that conserves metabolic resources (e.g., slows heart rate and breathing, decreases blood pressure) and supports immobilization behaviors (e.g., passive avoidance, fainting); 2) a system that increases metabolic output (i.e., sympathetic nervous system) and supports mobilization of the trunk and limbs (e.g., active avoidance, fight-flight behaviors); and 3) a uniquely mammalian system integrating the regulation of striated muscles of the face and head with the heart (i.e., myelinated "vagal" pathways) to create a functional social engagement system that regulates the phylogenetically older systems, often through social interaction, to promote physiological resilience and optimize health growth and restoration. Functionally, the theory proposes that modification of these "classes" of behaviors (immobilization, mobilization, and social engagement) will be optimized by monitoring autonomic variables and understanding the contextual cues that trigger transitions in autonomic state. Consistent with this model several variables, independent of stimulus manipulations, characterizing experimental conditions, and participants in behavior modification protocols (e.g., context, development, illness, medication, etc.) will influence the accessibility of different classes of behavior to stimulus control.