The Vagus Nerve – its many roles and functions

Human Brain
vagus_nerve_overview

The Vagus Nerve interacts with all of the organs that it touches – bringing healing acetylcholine.

Over the next 3 posts, Rebecca and I will be introducing you to the Vagus Nerve, what it is, what its functions are, and how you can use that knowledge for optimal brain-body health. Why is this nerve important? Why should we care?

Research has found that the neurotransmitter acetylcholine acts as a brake on inflammation in the body[4]. Stimulating your vagus nerve sends acetylcholine throughout your body, not only making you feel relaxed, but also putting out the fires of inflammation – something that happens in response to stress[1]. Further to this, acetylcholine is also responsible for learning and memory.  You can’t learn or heal though, if you stay in stress mode.

The vagus nerve is the 10th cranial nerve in your body. It is a very long nerve running from the hypothalamus area of your brain, chest, diaphragm, and to your intestines.  It wraps around your heart and core area (Hara point and solar plexus centre) – areas traditionally considered to be the seat of intuition and compassion.

The vagus nerve activates the parasympathetic nervous system (PNS), which manages your relaxation response, and in turn, helps you to control the health of your immune cells, organs and tissues, and even your stem cells. Twenty percent of the fibres of the vagus nerve control the organs which ‘maintain’ your body (the heart, digestion, breathing, glands). The other 80 percent of its fibres send information from your gut to your brain. (We will be writing more about the gut-brain relationship in another blog article).

One of the key roles that the vagus nerve plays, is acting as the “reset” button after your internal alarm system has been set off – i.e., in response to some type of perceived threat (a stress response). This nerve then communicates with the rest of your body to tell you that the threat is gone and that all of your bodily functions can now return to normal, healing mode.

Research has linked the vagus nerve to improved neurogenesis (creation of new brain or neuronal cells), and increased brain-derived neurotrophic factor (BDNF) factor.  BDNF is like a fabulous super-food for your brain cells.  It helps with repair of brain tissue, actual regeneration throughout the whole body.

These [5] and other researchers have found that stem cell growth is directly connected to vagus nerve activity.  Activating the vagus nerve can stimulate stem cells to produce new cells and even repair and rebuild your organs.

In the third installment of this blog, we will discuss further how the sympathetic and parasympathetic nervous systems work. For now, it is important to know that if you are living in stress mode, your body is unable to heal itself. The hormones that are triggered by stress actively block the healing and resting response of the body. Stress can create a number of negative effects including: depression, anxiety, insomnia, anger, difficulty with decision making, violence, difficulty with thinking and attention.

Fortunately, there are many ways to activate the vagus nerve and turn your relaxation response back on. An easy, inexpensive way to do this is to just breathe.  When you take a deep inhalation through the mouth, relax and expand your diaphragm, your vagus system kicks in, and your parasympathetic nervous system is activated. Then exhale via the nose and feel the stress leaving your body. The result? Your cortisol levels are reduced, and your brain heals.

Next:  Activating the Vagus Nerve.

Reference(s)

  1. Sloan, R. P., et al. 2007. RR interval variability is inversely related to inflammatory markers: The CARDIA study. Mol Med 13 (3-4):178-84.
  2. “Ultra-Longevity” by Mark Liponis, MD
  3. “Prime-Time Health” by William Sears, M.D. with Martha Sears, RN
  4. Pavlov, V.A., and K.J. Tracey. 2005. The cholinergic anti-inflammatory pathway. Brain Behav Immun 19 (6):493-99.
  5. Theise, N.D., and R. Harris. 2006. Postmodern biology: (adult) (stem) cells are plastic, stochastic, complex, and uncertain. Handb Exp Pharmacol (174):389-408.
  6. Your Brain on Food by Gary L. Wenk.
  7. The vagus nerve is located within the brain stem. It enters the nucleus tractus solitarius and then travels through the parabrachial nucleus. It then splits upward into a path which stimulates the thalamus (this path affects the central cortex), and a lower path into the limbic system (“your primitive brain where security is important). The limbic system oversees a number of anatomical/functional regions. The hypothalamus is responsible for ‘fight or flight’ responses, feeding/survival, and mating. The amygdala is where you feel joy, humour, anger, etc. In mammals, it appears that it is where all of the species-specific programmed actions come from; thus, it is crucial for survival. In Post-Traumatic Stess Disorder (PTSD), the activity of the amygdala is altered. The limbic system also contains the four brain reward systems.