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Posts Tagged ‘parasympathetic nervous system’

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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Was checking out the new Body Browser by Google.  Yogis seem to be very knowledgeable about anatomy and physiology, so perhaps this might be a useful instructional tool.  My favorite item to view is the vagus nerve, which – as I’ve blogged about here, here and here – is nothing short of a real live Kundalini serpent inside your body (well, perhaps a little short, insofar as the nerve does not extend all the way to the sacrum and muladhara, but rather just to the swadhisthana chakra).  Seriously though, clinical studies have shown that stimulation of this nerve, brings a relief from anguish, and many a yogi knows how to activate this nerve via breathing and other bodily maneuvers.  Here’s a screenshot from the body browser.

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Gita Chapter 11:32
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This post was graciously hosted @ Yoga Gypsy several weeks ago.

In Chapter 8 of B. K. S. Iyengar‘s Light on Pranayama, he quotes the Bhagavad Gita (VI 17) saying, “Yoga destroys all pain and sorrow”.   Nice! and this is just one of dozens of poetic and inspiring sentiments that are woven into the otherwise detailed and rigorous methods described by Iyengar for the training of the lungs, diaphragm and intercostal muscles.  Although I know the training is extensive and will surely take many years to master,  I can’t help wonder how much pain and sorrow,  realistically,  might be alleviated by the mastery of something as basic as – you know – breathing?

How might this work?  I mean, pain is something that happens in your body and in your mind.  How might mastery of deep and controlled breathing alleviate pain?

It turns out that there is a scientific research journal – Pain – that is dedicated to these types of questions.  A recent article, “The effects of slow breathing on affective responses to pain stimuli: An experimental study”  [doi:10.1016/j.pain.2009.10.001]  by Alex Zautra and colleagues investigates the role of breathing in relief from chronic pain.  The authors base their research on a specific neuroanatomical model of emotion and pain regulation:

The homeostatic neuroanatomical model of emotion proposes that the left forebrain is associated predominantly with parasympathetic activity, and thus with nourishment, safety, positive affect, approach (appetitive) behavior, and group-oriented (affiliative) emotions, while the right forebrain is associated predominantly with sympathetic activity, and thus with arousal, danger, negative affect, withdrawal (aversive) behavior, and individual-oriented (survival) emotions. …  The homeostatic neuroanatomical model of emotion suggests that central sensitization of pain in FM patients results in part from a relative deficit of activity in the parasympathetic branch of the ANS required for down-regulation of negative emotion and pain experience.

In basic terms, the researchers suggest that if one can increase activity of the parasympathetic nervous system, then one will experience relief from pain.  So they want to evaluate whether deep breathing increases activity of the parasympathetic nervous system?  In Chapter 4 of Light on Pranayama (Pranayama and the Respiratory System), Iyengar provides many detailed anatomical drawings of the musculature, skeletal and neural machinery related to breathing, but unfortunately no details on the role of parasympathetic vs. sympathetic nervous systems per se.  The authors however, point to a previous study that showed slow breathing increases activation of bronchiopulmonary vagal afferents and produces enhanced heart rate variability, which reflects increased parasympathetic tone – so the scientific evidence points in the right direction.

To test the notion themselves, the investigators asked a group of healthy adult females to wear a small thermal device on the thumb that could be heated and cooled to produce varying levels of moderate discomfort (pain).  By asking the volunteers to experience the thermal discomfort when breathing normally vs. breathing in a slower, deeper manner, the investigators could begin to assess whether the experience of pain (a self-reported value between 1 and 11) was different between the two breathing conditions.

The results showed that the volunteers self-reported less pain (given the same amount of thermal stimulation) when performing deep, slow breathing.

Very neat.  Perhaps not a surprise to yogis 3,000 years ago nor experienced yogis today, but very exciting to see how the practice of Pranayama can engage a neuroanatomical system for the relief of suffering.  In a previous post on the neural stimulation of this system – and its relation to Kundalini – it has become even more clear how potent this system can be!

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Hatha Yoga Video - Revolving Lunge Pose
Image by myyogaonline via Flickr

Does yoga feel good?  Do you feel good during the practice – moving your body through the bending, twisting, inverting etc.?  Be honest. I mean, since you’re probably sore as hell the next morning … if you don’t feel good during the practice, why would you bother at all?

Now that I have a tad of strength in my arms and shoulders, I think I can say that, “yes” I do feel good and enjoy the practice … but usually just for the first 20 minutes or so before I start playing the frantic “just keep up with the instructor and hope for a break” game.

Some say that their good feelings come from the relaxed meditative state that yoga puts them in.  Some folks just like to move their bodies and are attracted to the strange and exotic beauty of the postures.  I always enjoy the music.

But where do these good feelings come from?   Aren’t they just in my head?  Do I really need to move my body to feel good?  Why not just sit and breathe?

It turns out that there is a scientific theory on this topic.  The so-called Somatic markers hypothesis that suggests that afferent feedback from the body to the brain is necessary for generating our feelings.  For example, stimulation of the vagus nerve (aka Kundalini serpent) makes us feel good, while individuals with spinal cord damage who lack afferent input from the body reportedly have blunted emotions.

In his research review article, Human feelings: why are some more aware than others? [doi:10.1016/j.tics.2004.04.004] Dr. Bud Craig from the Barrow Neurological Institute reviews the science of this topic and lays out the neural circuitry that goes from body to brain and is necessary for us to FEEL.

These feelings represent ‘the material me’, and so this broader concept of interoception converges with the so-called somatic-marker hypothesis of consciousness proposed by Damasio. In this proposal, the afferent sensory representation of the homeostatic condition of the body is the basis for the mental representation of the sentient self.  Recursive meta-representations of homeostatic feelings allow the brain to distinguish the inner world from the outer world. Most strikingly, degrees of conscious awareness are related to successive upgrades in the cortex (a target of visceral afferent activity), supplementary motor cortex (involved in manual responses), and bilateral insular cortices. This pattern supports the general view that a network of inter-related forebrain regions is involved in interoceptive attention and emotional feelings.

Amazingly, it seems that humans have evolved several unique adaptations that make us able to convert bodily sensation into self-awareness.

For instance, a novel cell type, the so-called spindle cell, is exclusively located in these regions of the human brain. Recent evidence indicates a trenchant phylogenetic correlation, in that spindle cells are most numerous in aged humans, but progressively less numerous in children, gorillas, bonobos and chimpanzees, and nonexistent in macaque monkeys. Notably, this phylogenetic progression also parallels the results of the mirror test for self-awareness.

The rapid development of right Anterior Insula within a brief evolutionary timescale suggests that nested interoceptive re-representations could be directly related to the advantages of advanced social interaction.

So it seems that we human beings rely on bodily awareness to attain emotional awareness.  This sounds very yogic and something the yoga practice helps to develop.  Feel your body –> feel your emotions!

 

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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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Oregon Health & Sciences University
Image by drburtoni via Flickr

A recent scientific study of yoga and fibromyalgia has been buzzing around the web (here, here, here, here).  The study is entitled, “A pilot randomized controlled trial of the Yoga of Awareness program in the management of fibromyalgia” [doi: 10.1016/j.pain.2010.08.020] and is one of the most scholarly articles on the science of yoga that I have ever read (more posts to come on this research article). In a nutshell:

53 women who have suffered with fibromyalgia for 1-10+ years were randomly separated into a test group (25 women) who participated in an 8-week Yoga of Awareness course vs. a control group (28 women) who participated in so-called routine care for fibromyalgia.  After the 8-week course, the test (yoga) group showed greater improvements in a number of fibromyalgia symptoms than the control group.

The results are big news – not only for people who suffer from fibromyalgia – but for many others who suffer with chronic pain.  The results suggest that yoga works!  and may be worth a try!

One of the things I found so great about the article, is the way the authors delved into the question of WHY yoga works and why it may be a rather ideal adjunct to traditional medical therapy.  Here’s a passage from the article:

The intention of the yoga program we employed was to fulfill the need for both exercise and coping skills training as effective counterparts to pharmacotherapy for FM. Recent reviews of exercise trials concur that aerobic exercise and also strength training usually improves some FM symptoms and physical functioning, but rarely shows effects on pain or mood. In contrast, reviews of FM coping skills trials have concluded that such treatments usually show mild to moderate post-treatment effects on pain, mood, and disability. However, several reviews have emphasized that the best results have been produced by multi-modal interventions that combine both exercise and coping skills training.

What made a this yoga intervention so innovative – from a purely medical or clinical perspective – is the way it aimed to treat BOTH body and mind.  Note how the medical world has a way of divvying up treatments into those that are specific to the body and those that are specific to the mind.   Perhaps, it is starting to dawn on modern medical practice that this separation does not work well for certain ailments – particularly for the treatment of chronic pain.

Credit two unassuming yoga instructors for this!

It turns out that the lead authors for the research are James W. Carson and Kimberly M. Carson from the Department of Anesthesiology and Peri-operative Medicine and School of Nursing, Oregon Health & Science University in Portland, Oregon.  They are strangers to neither science nor the practice of yoga.  From their website – Jim is a former yogic monk with more than 25 years of teaching experience while Kimberly is an instructor of Kripalu Yoga – in addition to numerous other academic and yogic accomplishments.

Yogis doing science?

Of course!  This should not come as a surprise.  Ancient yogis were dabbling in psychology, chemistry and medicine LONG before our modern era of science came along.   Just like modern medical practitioners – they wanted to help people cope with suffering 🙂

Today, there is much to be gained in scientific research on the mind-body interface.  A recent article in Nature Medicine reviews the neuroscience of this most mysterious interface.  “Getting the pain you expect: mechanisms of placebo, nocebo and reappraisal effects in humans” [doi:10.1038/nm.2229].  Will try and explore some of these brain-body connections and the way yoga practice engages them in future posts (related post here).

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