Vagus Nerve
The vagus nerve is the longest and most complex cranial nerve; it is also known as the 10th (of 12) cranial nerve. It runs from the brain stem down to a part of the colon. The term “vagus” originates from Latin meaning “wandering” because the nerve wanders and carries information bi-directionally from the brain into organs in the neck, chest, and abdomen (Sampson, 2017). The Vagus nerve has sensory functions as well as motor functions. The sensory functions include; delivering somatic sensation information for the ear and particular parts of the throat, providing visceral sensation information for the larynx, esophagus, lungs, trachea, heart and the majority of the digestive tract, and it plays a role in the experience of taste (Hammond, 2018).
The motor functions include; stimulating muscles in the pharynx, larynx, and the soft palate, stimulating muscles in the heart and stimulating involuntary contractions in the digestive tract, including the esophagus, stomach, and most of the intestines (Hammond, 2018).
The Polyvagal Theory
The Polyvagal Theory was first introduced in 1994 by Dr. Stephen Porges. Dr. Porges started his exploration into the topic nearly four decades ago with an initial interest in the possibility of utilizing physiological measures to understand psychological states (Porges, 2011). The Polyvagal theory explains the autonomic nervous system as having three hierarchical subdivisions related to interpersonal connection and social behaviors (Porges, 2011). The oldest subdivision is the “Dorsal Vagal” and is the part of the parasympathetic nervous system that enables the “freeze” response in fight, flight, freeze. The next subdivision is our sympathetic nervous system that allows the fight/flight response. The third and most complex is the ventral vagus, our mammalian parasympathetic social engagement system. This sophisticated system of myelinated neural fibers that originate in the brainstem commands our heart rate, breathing, facial muscles, hearing, and vocalizing. Neuroception is a term coined by Dr. Porges, and it refers to how neural circuits determine if people, places, or situations are safe. Neuroception happens in the primitive parts of the brain and is not accessible to active cognition (Porges, 2011). Even though we may think we are safe if neuroception has determined a person is unsafe, our heart rate may increase, other defensive strategies may be employed, and typical social engagement may be difficult.
The polyvagal theory operates from a hierarchical perspective in that all three of our subdivisions follow a natural order. This order is dependent on the neuroception of danger or safety that has been determined. For example, if the situation is deemed safe, we are free to employ the ventral vagal social engagement system which means we feel free to express our feelings, be ourselves, use facial expressions easily and regulate voice pattern. Conversely, if neuroception determines a situation is unsafe often unbeknownst to us, our sympathetic nervous system will take over, and if that system fails to achieve safety dorsal vagal mode, or shutting down “freeze” response will be engaged (Porges, 2011). This is an automatic process and can happen without a cognitively available trigger.
Trauma therapists and trauma survivors are consistently working with fight, flight, or freeze reactions (Van der Kolk, 2011). Individuals living with complex PTSD often experience emotions that are difficult to regulate, and small frustrations can quickly escalate to a crisis, minor clashes in miscommunication can easily turn into dramatic interpersonal conflicts.
When PTSD was first conceptualized only single, dramatic incidents were the focus. Eventually, we have come to understand that the most intense and disruptive dysregulation happens with individuals who have lacked, safe, consistent, and attuned caregivers. Loss of caregivers, emotional abuse, neglect, chronic misattunement, and inconsistency have presented as the primary contributors to a wide variety of psychiatric disorders (Van der Kolk, 2011).
With the advancements in neurobiology, researchers have been able to demonstrate the neurophysiological and physiological underpinnings of arousal. The relationship between the sympathetic nervous system and the hypothalamic-pituitary-adrenal (HPA) axis have been the focus of this research (Porges, 2011). The understood connection between the sympathetic nervous system and the HPA axis has led to the involvement of mind-body approaches in the treatment of trauma-related disorders.
One of the most crucial discoveries in psychology has been that the inability to establish safe and secure early attachment bonds leads to a weakened capacity to regulate undesirable emotions later on (Van der Kolk, 2011). Over 50 years of attachment and neurobiological research have demonstrated that the internal self-regulatory process of an individual is dependent upon the level of attunement provided by their external (usually parental) sources of regulation early in their development (Van der Kolk, 2011). In short, a history of chronic misattunement with one’s primary caregivers predisposes people to have a hard time managing their negative emotions as adults.
Mind-body approaches and the Vagus nerve
The polyvagal approach involves working with the social engagement system (Ventral Vagus) and helping our neuroception to accurately detect safety or danger so we can feel more in charge of our responses to our environments.
Integrative healing approaches combine ancient wisdom with modern science. Many integrative practitioners, myself included, believe that the mind-body wants to heal it’s just that sometimes we do not have the tools to tap into our natural self-healing capabilities. Research has demonstrated that high vagal tone ( a vagus nerve that is toned and exhibits working vagus nerve activity) aids in digestion and regulating blood glucose levels helping to reduce the chances of cardiovascular disease, stroke, and diabetes. On the other hand, low vagal tone has been connected with chronic inflammation. Current research is demonstrating that strengthening vagal tone can help relieve anxiety, depression, brain fog, fatigue, and digestive struggles (Aylward, 2019).
Breathwork can be an accessible and effective way to increase vagal tone. By slowing down our breath and extending the exhale, we can activate what is termed the vagal brake and elicit the relaxation response. Research has demonstrated that mindful, slow diaphragmatic breath increase vagal tone. There are also yoga postures that can help stimulate the vagus nerve, such as heart openers, cat-cow movement, and spine twists. Yoga Nidra or restorative yoga can also be a beautiful practice to help the body learn to engage the relaxation response. Though be mindful of your physical capacities and where you are in your healing journey. In the beginning, too much stillness can be unbearable for a nervous system that does not yet know how to calm down. Utilizing mind-body approaches for healing is about learning to hear what your system needs from a compassionate, non-judgmental space and working to meet that need to the best of your ability.
References:
Aylward, H. (2019). Thirve naturally by activating your vagus nerve. Retrieved from https://www.yogatoday.com/blog/thrive-naturally-by-activating-your-vagus-nerve
Hammond, N. (2018, July 31). Vagus Nerve Overview. Retrieved from https://www.healthline.com/human-body-maps/vagus-nerve
Porges, SW. (2011) The polyvagal theory neurophysiological foundations of emotions attachment communication self-regulation. New York, NY: W.W. Norton & Company Inc.
Sampson, S. (2017, June 28). Everything you need to know about the vagus nerve. Retrieved from https://www.medicalnewstoday.com/articles/318128.php
Van der Kolk, B. (2011)Foreword in the polyvagal theory neurophysiological foundations of emotions attachment communication self-regulation. New York, NY: W.W. Norton & Company Inc.
