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

PainSci » bibliography » Porges 1995
Tags: mind, classics, random

PainSci notes on Porges 1995:

This is a simple translation of the abstract: no editorializing here, just putting it into relatively plain English.

The vagus nerve regulates the guts, including and especially the heart. Its emerges from two distinct areas of the brain, the nucleus ambiguus and dorsal motor nucleus. These regions are both connected to the heart via the vagus nerve, but (hypothesis) the NA fibres are responsible for coordinating heart rate with respiration (respiratory sinus arrhythmia). “Divergent shifts in RSA and heart rate are explained by the independent actions” of these areas. Polyvagal theory emphasizes the evolution of this system and proposes that mammals (as opposed to reptiles) have an area of the brain stem (including NA) devoted to attention, motion, emotion, and communication, which can sometimes be at odds with signalling from the dorsal motor nucleus, and this could explain clinical disorders like sudden infant death syndrome and asthma. So polyvagal theory is basically the idea that the viscera are regulated (via the vagus nerve) by two different parts of the brain stem that don’t always play well together.

original abstract Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

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.

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