Polyvagal Theory
Overview
Polyvagal theory is an innovative theory that examines adaptive behavioral strategies alongside modern understandings of both neuroanatomy and neurophysiology.[1] Providing a shift from a traditional subjective understanding of trauma experiences and responses within the individual to a more objective science, polyvagal theory attempts to elucidate evolutionary mechanisms for survival. This theory connects the various functions of the autonomic nervous system to the vagus nerve in order to better understand atypical autonomic function and behaviors.[2] Thus, polyvagal theory can account for certain affective experiences, emotional expression, facial gestures, vocal communication, and contingent social behavior often seen in trauma survivors.[3] Polyvagal theory as an emerging study of the neurobiological mechanisms behind trauma and safety has far reaching implications. When integrated into clinical settings and other societal institutions, ranging from healthcare to education, polyvagal theory may play a key role in promoting and enhancing health, sociality, and a greater sense of well-being within individuals.[4]
History/Development
Polyvagal theory was first conceptualized by psychologist Stephen Porges in 1995. Though Porges has since published numerous articles related to expansions and empirical research studies related to this early theory, he attributes the idea of polyvagal theory to figures such as Darwin who made the connection between the pneumo-gastric [vagus] nerve on the heart and the brain in the context of reactivity and communication pathways that are bidirectional.[5] There existed the general idea that the vagus nerve modulated “tone” to several target organs; in other words, the vagus modulated physiological changes in the body, particularly related to markers of stress vulnerability (e.g., respiratory responses, heart rate changes) but these pathways were not well differentiated or understood. Using infant’s heart rate patterns to index vagal activity, Porges et al. (1992) observed an inconsistency in the function of the vagal nerve.[6] Through experimentation, he found that vagal mechanisms mediate both respiratory sinus arrhythmia and bradycardia in human fetuses; however this is contradictory as the former is protective and the latter is potentially lethal. This inconsistency was thus deemed the “vagal paradox” and served as the motivation behind exploring the specific mechanisms of the vagal nerve which is now outlined in a more comprehensive and developed polyvagal theory.[7]
Three Key Principles
Since 1995, Stephen Porges outlined several principles related to the model of Polyvagal Theory. The principles within these model are all encompassed within the idea that the autonomic nervous system is an integrated system that includes pathways conveying information regarding the visceral organs and the brain areas (e.g., medulla, hypothalamus) that interpret this feedback and exert control over the motor output of the organs.[8]
Three of the distinguishing tenets of Polyvagal Theory according to the Polyvagal Institute (PVI) specifically related to human behavior, emotional regulation, and survival mechanisms include:[9]
Hierarchy of the Autonomic Nervous System (ANS): There is a neurophysiological basis for the emotional experiences and affective processes that are major components of social behavior shown by the identification and adaptive function of three phylogenetically-ordered neural circuits (Figure 1).[10]
Neuroception: This Is a process that takes cues from specific features in the environment to elicit specific physiological states that support either fight-flight or social engagement behaviors. Neuroception involves areas of the temporal cortex that interpret biological movement and social interactions. It is dependent upon the individual’s current autonomic state and historical flexibility to move back and forth among states; for example, individuals with a history of severe adversity may find themselves habitually hypervigilant in anticipation of threats.
Co-regulation: The social engagement system allows us to send signals of safety or danger to one another. For example, the ventral vagal complex in the brainstem calms our reaction to threats while simultaneously enabling facial expressions, head movements, and vocal intonations that let others know we are open to friendly communication.
Phylogenetic Stages of Development
Figure 1. Autonomic nervous system components are linked to specific behaviors regarding social communication (e.g., “safety,” connection, active listening), mobilization (e.g., “fight or flight” behaviors), or immobilization (“freeze,” behavioral shutdown). The three circuits outlined above are responsible for adaptive responses to safe, dangerous, or life threatening events and contexts.
Clinical Applications for Trauma
Polyvagal theory can be applied to clinical practice as both the therapist and client can begin to rationalize and understand key insights into the workings of biological reactions and affective states within traumatized individuals. With the three phylogenetically ordered states (ventral, sympathetic, dorsal), it is essential for therapists to help clients establish safety by guiding them back to their ventral vagal state. For trauma survivors, the nervous system often becomes fixed in the sympathetic or dorsal states (i.e, fight/flight or freeze mode) without returning to the ventral state (i.e., safety mode). Being stuck in these two states may perpetuate feelings of loneliness, fear, anxiety, depression and dysregulation which can significantly impact one’s daily life.[11] Additionally, physiological changes may take place in the body including high blood pressure, elevated levels of stress hormones, a weakened immune system, digestive issues, malfunctioning organs, insomnia, muscle tension, and pain.[12]
Therapists may utilize reflective listening techniques in order to cultivate feelings of safety as well as find out if there are specific triggers, such as loud noises, physical touch, or other sensory cues, that cause their patient to feel unsafe. Many therapists also choose specific bodily awareness therapies like cognitive behavioral therapy (CBT) and dialectical behavioral therapy (DBT) to help clients feel more embodied in moments of tension so they may effectively re-evaluate safety situations and shift away from automatic shutdown responses.[13] One recent systematic review by Poli et al. (2021) which incorporates polyvagal theory into embodied contemplative practices found mindfulness-related interventions promoted parasympathetic activity, an increased vagal tone and improvements in individuals with PTSD and OCD symptoms. Furthermore, researchers stated that polyvagal theory supports the utilization of mindfulness-related and compassion-related meditations that could be used to expand the capacity of the ventral vagal complex to regulate the present state and to promote resilience.[14]
Other Therapies to Incorporate Polyvagal Theory
Polyvagal Theory argues against the usage of exposure therapies for trauma survivors as these may instead trigger defense systems and result in heightened sensitivity. Thus, Porges argues that it is more effective to down-regulate defense systems through top-down influences—such as therapies involving listening, music, play, and the body.[15]
Music Therapy: This therapy encourages the use of extended breath in regulation of the vagus nerve. Music therapy emphasizes the use of increased exhales that may elicit a calmed physiological state, forces the usage of middle ear muscles in active listening, and uses a social engagement system which may all help stimulate and eventually regulate the vagus nerve.
Listening Therapy: This type of therapy is specifically in reference to the Listening Project Protocol (LPP) designed by Porges. The aim of listening therapy is to use vocalizations in order to exercise the neural regulation of the middle ear muscles which send feedback to the nervous system letting it know that the environment is safe. This can reduce defensive behaviors and has been shown to foster better communication, sociality, and learning, especially within children.
Body-Centered Therapy: Some low-intensity movement based therapies such as yoga and tai-chi emphasize long exhales and diaphragmatic breathing which naturally relaxes the nervous system. Yoga and other mindfulness-based therapies have been shown to reduce stress and anxiety which in turn contributes to the regulation of the vagus nerve.
Polyvagal Theory has a plethora of clinical applications especially when used in the context of helping therapists’ approach their practice with a more trauma-informed, comprehensive understanding of the affective experiences, emotions, and behaviors of their clients. Therapists may integrate the framework of polyvagal theory into their own therapy practice in order to better promote well-being and a sense of safety and connection in trauma patients and/or those who have had a history of adversity.
Contributed by: Kaylin Ong
Editor: Jennifer (Ghahari) Smith, Ph.D.
References
1 Porges, S. W. (2009). The polyvagal theory: New insights into adaptive reactions of the autonomic nervous system. Cleveland Clinic Journal of Medicine, 76(Suppl_2), S86–S90. https://doi.org/10.3949/ccjm.76.s2.17
2 Wellness. (n.d.). Polyvagal Institute. https://www.polyvagalinstitute.org/
3 Porges (2009)
4 Porges, S. W. (2022). Polyvagal Theory: A Science of Safety. Frontiers in Integrative Neuroscience, 16(871227). https://doi.org/10.3389/fnint.2022.871227
5 Porges (2009)
6 Porges, S. W. (1992). Vagal tone: a physiologic marker of stress vulnerability. Pediatrics, 90(3 Pt 2), 498–504. https://pubmed.ncbi.nlm.nih.gov/1513615/
7 Ibid.
8 Porges, S. W. (1995). Orienting in a defensive world: Mammalian modifications of our evolutionary heritage. A Polyvagal Theory. Psychophysiology, 32(4), 301–318. https://doi.org/10.1111/j.1469-8986.1995.tb01213.x
9 What is Polyvagal Theory. (n.d.). Polyvagal Institute. https://www.polyvagalinstitute.org/whatispolyvagaltheory
10 Porges (1995)
11 Polyvagal Theory: An Approach to Understanding Trauma | Psychology Today. (n.d.). Www.psychologytoday.com. https://www.psychologytoday.com/us/blog/talking-about-trauma/202206/polyvagal-theory-approach-understanding-trauma
12 Warren, S. (2022, February 21). Using Polyvagal Theory in Clinical Settings. Somatic Movement Center. https://somaticmovementcenter.com/polyvagal-theory-therapy/
13 Wagner, D. (2016, June 27). Polyvagal theory in practice - Counseling Today. Counseling Today. https://ct.counseling.org/2016/06/polyvagal-theory-practice/
14 Poli, A., Gemignani, A., Soldani, F., & Miccoli, M. (2021). A Systematic Review of a Polyvagal Perspective on Embodied Contemplative Practices as Promoters of Cardiorespiratory Coupling and Traumatic Stress Recovery for PTSD and OCD: Research Methodologies and State of the Art. International Journal of Environmental Research and Public Health, 18(22), 11778. https://doi.org/10.3390/ijerph182211778
15 Warren (2022)