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Polyvagal theory (PVT) is a collection of proposed evolutionary, neuroscientific, and psychological constructs pertaining to the role of the vagus nerve in emotion regulation, social connection and fear response. The theory was introduced in 1994 by Stephen Porges. There is consensus among experts that the assumptions of the polyvagal theory are untenable. PVT is popular among some clinical practitioners and patients, but it is not endorsed by current social neuroscience.Polyvagal theory takes its name from the vagus, a cranial nerve that forms the primary component of the parasympathetic nervous system. The traditional view of the autonomic nervous system presents a two-part system: the sympathetic nervous system, which is more activating ("fight or flight"), and the parasympathetic nervous system, which supports health, growth, and restoration ("rest and digest"). Polyvagal theory views the parasympathetic nervous system as being split into two distinct branches: a "ventral vagal system" which supports social engagement, and a "dorsal vagal system" which supports immobilisation behaviours, both "rest and digest" and defensive immobilisation or "shutdown". This "social engagement system" is a hybrid state of activation and calming that plays a role in our ability to socially engage. Theory The vagus, or tenth cranial nerve, is a primary component of the autonomic nervous system, which operates the internal organs. It transmits parasympathetic signals to and from the heart, lungs, and digestive tract. The vagal system is claimed to be inhibitory of primal instincts by being part of the parasympathetic nervous system, in opposition to the sympathetic-adrenal system, involved in mobilization behaviors.Polyvagal theory was developed in 1994 by Porges, who at the time was director of the Brain-Body Center at the University of Illinois at Chicago. It focuses on the structure and function of the two efferent branches of the vagus cranial nerve, which originate from the medulla. Each branch is claimed to be associated with a different adaptive behavioral strategy; the ventral branches more restful in nature and the dorsal ones more active in nature. According to the theory, three organizational principles can be distinguished:Hierarchy: The autonomic nervous system reacts in three reaction patterns, which are activated in a specific order. Neuroception: In contrast to perception, it is here a cognition without awareness, triggered by a stimulus such as danger. Co-regulation: The need to feel safe enough to allow oneself to be in relationships, which is difficult for traumatized people.Porges describes the three neural circuits as regulators for reactive behavior. His findings were taken into account by some theorists of childhood trauma, with related techniques used by trauma therapists such as Bessel van der Kolk, Peter A. Levine and Marianne Bentzen. Anatomical hypothesis Polyvagal theory combines ideas from evolutionary biology and neurology, to claim that autonomic reactions have adapted to the phylogenetic development of neural circuits. It claims that the sympathetic nervous system, and two distinct branches of the parasympathetic nervous system, are phylogenetically ordered and activated for responses. The branches of the vagal nerve are claimed to serve different evolutionary stress responses in mammals: the more primitive branch is said to elicit immobilization behaviors (e.g., feigning death), whereas the more evolved branch is said to be linked to social communication and self-soothing behaviors. These functions are claimed to follow a phylogenetic hierarchy, where the most primitive systems are activated only when the more evolved functions fail.According to the theory, these neural pathways regulate autonomic states and the expression of emotional and social behaviour. It claims that in mammals, facial expressions are connected to internal physical reactions, such as cardiac and digestive changes, and in general physiological state dictates the range of behaviour and psychological experience.Claims about the nature of stress, emotion, and social behaviour, are traditionally studied via peripheral indices of arousal such as heart rate, cortisol level and skin conductance. Polyvagal theory champions the measurement of vagal tone as a new index of stress vulnerability and reactivity, including in populations with affective disorders. Proposed dorsal vagal complex (DVC) The dorsal branch of the vagus nerve originates in the dorsal motor nucleus and is postulated by polyvagal theory to be the phylogenetically older branch. This branch is unmyelinated and exists in most vertebrates. Polyvagal theory calls this the "vegetative vagus" because it sees it as being associated with primal survival strategies of primitive vertebrates, reptiles, and amphibians. Under certain conditions, these animals "freeze" when threatened, conserving their metabolic resources. This draws on the simplifying claims of the triune brain theory which are no longer considered accurate due to the many exceptions to this rule (see Triune brain § Status of the model).The DVC provides primary control of subdiaphragmatic visceral organs, such as the digestive tract. Under normal conditions, the DVC maintains regulation of these digestive processes. However, prolonged disinhibition can be lethal for mammals, as it results in apnea and bradycardia. Proposed ventral vagal complex (VVC) With increased neural complexity as seen in mammals (due to phylogenetic development) there is said to have evolved a more sophisticated system to enrich behavioral and affective responses to an increasingly complex environment. The ventral branch of the vagus originates in the nucleus ambiguus and is myelinated to provide more speed in responding. Polyvagal theory calls this the "smart vagus" because it associates it with the regulation of sympathetic "fight or flight" behaviors by way of social affiliative behaviors. These behaviors are said to include social communication and self-soothing and calming. In other words, this branch of the vagus is said to inhibit or disinhibit defensive limbic circuits, depending on the situation. Note: Attributing defensive behaviours purely to the limbic system is an oversimplification, as these are triggered by perceived threats, thus requiring an interplay of brain areas performing sensory integration, memory, and semantic knowledge with the limbic system to be elicited. Similarly, the regulation of emotions requires a complex interplay of higher cognitive areas with limbic ones. The vagus nerve mediates the control of supradiaphragmatic visceral organs, such as the esophagus, bronchi, pharynx, and larynx. It also exerts an important influence on the heart. When vagal tone to the heart’s pacemaker is high, a baseline or resting heart rate is produced. In other words, the vagus acts as a restraint, or brake, limiting heart rate. However, when vagal tone is removed, there is li.... Discover the Paul Grossman popular books. Find the top 100 most popular Paul Grossman books.