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Posts Tagged ‘Vagus nerve’

The ocean is an example of a natural resource.
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For most of us, the concept of “breath control” is silly.  I mean, like, I’ve been doing it naturally since I was, like zero years old … now you’re telling me I should work to control my breath?  Yep. 

Here’s an amazing physiological feat that your breath performs:

Respiratory sinus arrhythmia.

Respiratory sinus arrhythmia (RSA) is a naturally occurring variation in heart rate that occurs during a breathing cycle. Heart rate increases during inhalation and decreases during exhalation.

Heart rate is normally controlled by centers in the medulla oblongata. One of these centers, the nucleus ambiguus, increases parasympathetic nervous system input to the heart via the vagus nerve. The vagus nerve decreases heart rate by decreasing the rate of SA node firing. Upon expiration the cells in the nucleus ambiguus are activated and heart rate is slowed down. In contrast, inspiration triggers inhibitory signals to the nucleus ambiguus and consequently the vagus nerve remains unstimulated.

Adults in excellent cardiovascular health, such as endurance runners, swimmers, and bicyclists, are also likely to have a pronounced RSA. Meditation and relaxed breathing techniques can temporarily induce RSA. RSA becomes less prominent with age, diabetes and cardiovascular disease.

This is just obscure science-talk for the notion that slowing down and extending the breath is a good thing – good because increasing the length of one’s exhalation stimulates the vagus nerve which has wonderful effects on a person’s heart rate (slowing it), immune system, and sense of well-being (e.g., in 2005, the Food and Drug Adminsitration approved vagus nerve stimulation for the treatment of depression).

Yoga practitioners use something called ujjayi breathing wherein they constrict the back of the throat, which allows the breath to flow more slowly and evenly. This tends to increase Respiratory Sinus Arrhythmia and its concomitant health benefits. 

As Richard Freeman so eloquently describes in the video below, breath control is the heart, soul and root of yoga practice.

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Have you ever seen the list “100 Benefits of Meditation“?  Of course, many of these benefits are psychological. You know, things like: helps control own thoughts (#39) and helps with focus & concentration (#40).  But many of the 100 benefits are rather physical, bodily, physiological, immunological and even biochemical benefits (such as #16- reduction of free radicals, less tissue damage).

These are awesome claims, and I’ve certainly found that mediation helps me feel more emotionally balanced and physically relaxed,  but I’m wondering – from a hard science point of view – how legit some of these claims might be.  For example, “#12 Enhances the immune system – REALLY?  How might yoga and mediation enhance my immune system?

In a previous post on the amazing vagus nerve – the only nerve in your body that, like the ancient Kundalini serpent, rises from the root of your gut to the brain – AND – a nerve that is a key to the cure of treatment resistant depression – it was suggested that much of the alleviation of suffering that comes from yoga comes from the stimulation of this amazing nerve during postures and breathing.

Somehow, the ancient yogis really got it right when they came up with the notion of Kundalini serpent – so strange, but so cool!

I happened to stumble on a paper that explored the possibility that the vagus nerve might also play a role in mediating communication of the immune system and the brain – and thus provide a mechanism for “#12- Enhances the immune system” Here’s a quote from the article entitled, “Neural concomitants of immunity—Focus on the vagus nerve” [doi:10.1016/j.neuroimage.2009.05.058] by Drs. Julian F. Thayer and Esther M. Sternberg (Ohio State University and National Institute of Mental Health).

By the nature of its “wandering” route through the body the vagus nerve may be uniquely structured to provide an effective early warning system for the detection of pathogens as well as a source of negative feedback to the immune system after the pathogens have been cleared. … Taken together these parasympathetic pathways form what has been termed “the cholinergic anti-inflammatory pathway

The scientists then investigate the evidence and possible mechanisms by which the vagus nerve sends immunological signals from the body to the brain and also back out to the immune system.  Its not a topic that is well understood, but the article describes several lines of evidence implicating the vagus nerve in immunological health.

So bend, twist, inhale and exhale deeply.  Stimulate your vagus nerve and, as cold and flu season arrives, awaken the serpent within!

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What if you had magic fingers and could touch a place on a person’s body and make all their pain and anguish disappear?  This would be the stuff of legends, myths and miracles! Here’s a research review by Kerry J Ressler  and Helen S Mayberg on the modern ability to electrically “touch” the Vagus Nerve.

The article,  Targeting abnormal neural circuits in mood and anxiety disorders: from the laboratory to the clinic discusses a number of “nerve stimulation therapies” wherein specific nerve fibers are electrically stimulated to relieve mental anguish associated with (drug) treatment-resistant depression.

Vagus nerve stimulation therapy (VNS) is approved by the FDA for treatment of medication-resistant depression and was approved earlier for the treatment of epilepsy20.  …  The initial reasoning behind the use of VNS followed from its apparent effects of elevating mood in patients with epilepsy20, combined with evidence that VNS affects limbic activity in neuroimaging studies21. Furthermore, VNS alters concentrations of serotonin, norepinephrine, GABA and glutamate within the brain2224, suggesting that VNS may help correct dysfunctional neurotransmitter modulatory circuits in patients with depression.

This stuff is miraculous in every sense of the word – to be able to reach in and “touch” the body and bring relief – if not bliss – to individuals who suffer with immense emotional pain.  So who is this Vagus nerve anyway?  Why does stimulating it impart so many emotional benefits?  How can I touch my own Vagus nerve?

The wikipedia page is a great place to explore – suggesting that this nerve fiber is central to the “rest and digest” functions of the parasympathetic nervous system.  As evidenced by the relief its stimulation brings from emotional pain, the Vagus nerve is central to mind-body connections and mental peace.

YOGA is a practice that also brings mental peace.  YOGA,  in so many ways (I hope to elaborate on in future posts),  aims to engage the parasympathetic nervous system (slowing down and resting responses) and disengage the sympathetic nervous system (fight or flight responses).  Since we all can’t have our very own (ahem) lululemon (ahem) vagal nerve stimulation device, we must rely on other ways to stimulate the Vagus nerve fiber.  Luckily, many such ways are actually known – so-called “Vagal maneuvers” – such as  holding your breath and bearing down (Valsalva maneuver), immersing your face in ice-cold water (diving reflex), putting pressure on your eyelids, & massage of the carotid sinus area – that have been shown to facilitate parasympathetic (relaxation & slowing down) responses.

But these “Vagal maneuvers” are not incorporated into yoga.  How might yoga engage and stimulate the Vagal nerve bundle? Check out these great resources on breathing and Vagal tone (here, here, here).  I’m not an expert by any means but I think the take home message is that when we breathe deep and exhale, Vagal tone increases.  So, any technique that allows us to increase the duration of our exhalation will increase Vagal tone. Now THAT sounds like yoga!

Even more yogic is the way the Vagus nerve is the only nerve in the parasympathetic system that reaches all the way from the colon to the brain.  The fiber is composed mainly of upward (to the brain) pulsing neurons – which sounds a lot like the mystical Kundalini Serpent that arises upwards from within (starting at the root – colon) and ending in the brain.  The picture above – of the Vagus nerve (bright green fiber) – might be what the ancient yogis had in mind?

some updates:

here’s a great post on the importance of, and teaching of exhalation

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