Yoga, Balance and the Brain – Researched and written by Tamaryn Burton-Moore
“It would seem that dancing came into being at the beginning of all things…” (The Dance of Shiva)
“The most primitive part of the vestibular system… is estimated to be more than 500 million years old… These sensory organs evolved… before any other sensory system had developed” (Smith & Darlington 2013)
A great authority on yoga practice, Patanjali, uses the word sthitau (stability or steadiness) to describe the aim of practice. This ‘stilling’, and ‘steadying’, can also be thought of as a kind of balancing. In this ancient practice of yoga, involving focusing attention and calming the mind, it is said that (hopefully) “the senses are stilled… the intellect wavers not… [the yogi 1
has] steady control of the senses” . It is quite clear that modern postural yoga involves balance in quite an extensive way: from the classic postures like vrksasana (‘tree posture’, balancing on one leg with the foot to the inner thigh) or garudasana (eagle posture, balancing with the legs and arms bound) – to the seemingly infinite variations of hand-balance postures which have become such a popular expression of yoga these days.
Balance, like yoga, is also ‘ancient’ in the anatomical sense, being the first of our ‘senses’ to evolve – and it has a similar relationship to mind: “When we talk of ‘feeling settled’ or ‘unsettled’, ‘balanced’ or ‘unbalanced’, ‘rooted’ or ‘rootless’, ‘grounded’ or ‘ungrounded’, we 2
are speaking a vestibular language”, as well as a yogic one. What is the origin of this common rhetoric? How are yoga and balance connected and what are the benefits (if any) of doing balance postures besides the fairly obvious strength benefit?
Physiology and Neurology of Balance
The centre for balance in the brain is the vestibular apparatus, also called the ‘bony labyrinth’, a mechanism of the inner ear. It consists of three semicircular canals and two organs called otolith organs, which sit in the area where the three canals meet. Each of these assist in the different kinds of spatial orientation required for us to assume a position 3
or movement without losing balance. They do this by detecting different kinds of head movement, acceleration in each movement plane, and sensitivity to gravity.
This system uses reflexes related to the eyes (vestibulo-ocular reflex) and the musculo-skeletal system (vestibulo-spinal reflex) to affect vision and posture, so that our 4
gaze and body move in a way that keeps us balanced. The canals and organs of the inner ear contain fluid, hair cells and crystal-like structures. As we move or turn our heads the
1Iyengar 1966, 2 citing the Kathopanishad
2 Doidge 2007, 2
3 Doige 2007 ; Wazen 2008, 6-9
4 Smith & Darlington 2013; Cullen 2012
‘crystals’ move in the fluid and bend the hair cells. This bending activates a neural connection to the ‘vestibular nuclei’ which are involved in the reflexes contributing to 5 6
balance. This amazing little apparatus is often referred to as the sixth sense. A fundamental action of the nervous system: it is at work all the time, automatically, and it has been found to be increasingly involved in more and more brain circuits, probably because it is such a primitive sensory system. Its long evolution has resulted in contributions to multiple neural functions: “all sensory processing and motor planning is carried out within the 7
framework of the perception of gravitational vertical.” Ironically, it is our inner ‘labyrinth’, which helps us to orient ourselves in space.
The vestibular system is a function of the nervous system. Use of ‘reflexes’ means that sensory input is creating nerve signals which cause our muscles to move in particular ways. Nerve cells connect to each other by a tiny space called a synapse. The nerve cell has an output branch (the axon), through which the signal travels before crossing the synaptic space and entering another nerve cell’s input branch (dendrite) or another cell body in a 8
“telephone wire”-like system. The human brain has millions of these connections, and “everything the brain does is accomplished by the process of synaptic transmission”.9
These synaptic connections also have a plastic nature. Nerve cells and their electrical impulse system are largely “homogeneous”, meaning that the pathways created in the brain 10
can be switched, strengthened and weakened according to the ‘use it or lose it’ rule. This plasticity also has the capacity to cause “rigidity”. Although new connections are able to be formed in the brain, consistent use of the same neural pathways strengthens connections 11
and begins to automate actions and thought patterns. A well travelled synaptic pathway develops a myelinated (fatty) sheath along the axons, speeding up connectivity and contributing to the continued use of the route. As ‘use it or lose it’ suggests, the myelinated sheaths are also subject to decay if left unused. Learning and unlearning are both possible and necessary; and this plasticity/rigidity can be both a blessing and a curse.
Making Connections: Why We Should Learn Hand-Balances
Aging is inevitable: all sensory systems, including the vestibular apparatus, are subject to 12
decline. A young brain is, for the most part, easier to teach than an old one. It is also true, however, that some quite significant neuroplastic changes in the brain occur throughout life,
5 Wazen 2008, 10
6ibid, 3
7 Smith et. al. 2010, 5
8 Le Doux 2002, 40-1
9ibid2002, 2
10 Doidge 2007, 18; Le Doux 2002, 79
11 Doidge 2007, 208-9
12 Zalewski 2015, Doidge 2007, 253
13
possibly as a means to defend against age-related functional decline. Although cell decay in the brain is inevitable, the process by which new neural cells are produced, 14
“neurogenesis”, never stops and can be stimulated at any stage of life. Enriched environments (learning new skills), and moderate physical exercise, promote this brain cell production. Unfortunately, humans are habitual creatures, and as we age, we learn fewer new skills and often aging is also associated with a decline in physical activity. So, although the capabilities are there, the question remains as to how we access them.
Enter yoga. Encouraging and enhancing neuroplasticity is considered a kind of exercise for the brain and is facilitated by certain chemicals. The first of these is brain-derived neurotrophic factor (BDNF), a growth factor released when a synaptic connection is made.15 BDNF “supports the survival of existing neurons, and encourages the growth and differentiation of new neurons and synapses”; and it has been found to increase with consistent yoga practice.16
BDNF also encourages the activation of the nucleus basalis, which is involved with attentiveness. By releasing another chemical, acetylcholine, the nucleus basalis facilitates a ‘tuning in’, so that we can pay close attention, thereby retaining information. What this means is that through a heightened state of focus, we are able to put our brain into a “extremely plastic state”, allowing us to make neural changes which include learning new 17
skills or reinforcing existing ones. Studies on vestibular diseases have shown that loss of 18
vestibular function is accompanied by difficulties with attentiveness and concentration; not a surprising finding given that even simple balance exercises require an element of focus.
Postural yoga always includes balance. All movements technically require balance to some 19
extent, but yoga does have an added intentional element. Yoga practice is about stillness, 20
control of movement and focused attention, often facilitated by a strong gazing point or 21
drishti. The idea is not just to balance but to balance well, to move smoothly and effortlessly. I think most practitioners would agree that the way to do that is with sharp focus. I also think they would agree that there is a certain subtle rewarding feeling when a balance posture is executed in this way. This introduces us to one more important chemical, dopamine, which reiterates the release of acetylcholine, and sustains our focus for an
13 Doidge 2007, 253: “even in the midst of this deterioration,
the brain undergoes massive plastic reorganization, possibly to adjust for the brain’s losses.”
14 Doidge 2007, 250-1
15 Le Doux 2002, 81
16 Cahn et. al. 2017, 6
17 Doidge 2007, 80
18 Smith & Darlington 2013
19 Rogge et. al. 2017.
20 Villemure et. al. 2015, 8
21 Gothe & McAuley 2015, 4
extended period. Dopamine is also responsible for bringing us back onto the mat the next day.22
When these chemicals work together (as they most likely do in yoga balance postures), they keep our brains in this ‘plastic’ state of learning, allowing a play of neural connections. This may provide a space to somewhat train the vestibular mechanism by building skillful habits. Through exploration of what muscular actions are required, we can exercise and fine tune the ‘multisensory’ neural pathways, constructively providing the nervous system with 23
“proprioceptive, visual and tactile information”. By graduating towards complex or difficult balance postures we explore the range of the vestibular apparatus; and postures that require effort to master introduce a physical element, encouraging neurogenesis. Progression and variation is (literally) vital:
“Just doing the dances you learned years ago won’t help your brain’s motor cortex stay in shape. To keep the mind alive requires learning something truly new with intense focus. That is what will allow you to both lay down new memories and have a system that can easily access and preserve the older ones.”24
Staying Connected: Hand-Balances Work Your Memory
It follows naturally that building and sustaining neural pathways is associated with memory; and there are a whole host of memory-related benefits that seem to be the result of a healthy vestibular apparatus. Studies have shown that because the release of acetylcholine focuses 25
attention it improves working memory function; BDNF has been found to be essential to 26
long term memory; and dopamine has its role too, enhancing and preserving working 27
memory capacity. It has also been shown that a poorly functioning vestibular system is 28
accompanied by the deterioration of an important memory centre in the brain. The chemical cocktail released during the training of balance postures should therefore significantly improve our memory. If this connection of yoga practice to vestibular health and neuroplasticity is to hold up, it could then follow that consistent yoga practice results in better memory function.
When it comes to the brain’s memory function, it is the hippocampus that is generally 29
considered “crucially involved”. It assists in converting short-term to long-term memory, and
22 Doidge 2007, 71, 106-7. This also sets yoga apart from regular balance exercises. Plasticity is normally not effective in the bored brain.
23 Rogge et. al 2017, 8
24 Doidge 2007, 88
25 Croxton et. al. 2011
26 Bekinschtein et. al. 2008
27 Le Doux 2002, 189
28 Brandt et. al. 2005
29 ibid, 100
also facilitates spatial memory and navigation – i.e. how we orientate ourselves in space 30
(including control over posture) and how we remember familiar environments. Because of this, studies involving memory tend to focus on the hippocampus and the results are fairly unanimous. Balance related activities (such as dancing and slacklining) result in plastic 31
changes in the hippocampal area. Yoga practitioners are also found to have more 32
grey-matter volume in certain brain areas, one of which is the hippocampus. Other studies found that general balance training improved memory function irrespective of the cardiovascular element (separating vestibular-related benefits from exercise-related ones) ;33 and yoga practice was also found to improve memory function in multiple trials.34
But do we really need yoga? Surely we could just concentrate hard and practice lots of handstands to get these benefits? There is a final point to be considered here. While focused attention does facilitate memory, it also seems to have two branches which complicate the fact a little: sympathetic dominated attention is generally referred to as “effort” and involves a stress response, while parasympathetic dominated attention is considered “effortless” and encourages heart-rate variability – a distinctly unstressed physiological state.
35
The stress hormone, glucocorticoid, does not fit well with the chemical cocktail that was
seen to enhance neurogenesis, synaptic plasticity and hippocampal function. Instead it can actually destroy cells in the hippocampus “so that it cannot make the synaptic connections in neural networks that make learning and explicit long-term memory possible.”36
37
Severe stress has been found to affect memory retrieval and inhibit cognitive performance 38
in general. Calm attitude and self-regulation are important aspects of a yoga practice; and 39
yoga does assist in down-regulation of the stress-response. While minor or short-lived stress can have certain benefits, severe or prolonged stress does not; and balance postures in yoga require a calm but concentrated mind. Patanjali describes yoga practice as requiring both abhyasa (practice in the sense of striving) and vairagya (dispassion in the sense of letting go) so the measure of stress is important to regulate. Feeling ‘balanced’ and feeling ‘stressed’ are not exactly compatible, so a yogic approach to balance is probably going to yield better results both in the neuroplastic sense of enhancing our vestibular system as well as the resulting cognitive sense of memory improvement.
30 Previc et al 2014; Smith et. al 2010
31 Smith et al 2010, 3
32 Villemure et al 2015
33 Rogge et. al. 2017
34 Subramanya & Telles (2009); Gothe et. al. (2014)
35 Bruya B and Tang Y-Y (2018)
36 Doidge 2007, 240-1
37 Buchanan, T. W., Tranel, D., & Adolphs, R. (2006). See also Tatomir, A., Micu, C., & Crivii, C. (2014)
38 Gothe & McAuley 2015
39 Ibid; Woodyard 2011
Conclusion: Feeling Connected
We have seen how our vestibular ‘labyrinth’, an ancient and integral part of our nervous system, is intricately connected to other aspects of cranial physiology and cognition. It affects parts of the brain associated with neurogenesis; the attentive, intentional ‘exercising’ of it encourages plasticity and learning; it is also inextricably linked to memory, meaning the benefits go beyond merely improve balance skills but spill over into other areas of cognition. We have also seen that a yogic approach might well enhance these benefits.
However, we have barely touched on the impact of the vestibular apparatus on our lives. Why is it important for us to feel balanced, to feel orientated in our own inner ear labyrinth? To put the question in yogic terms, why do we attempt to realign our energy into the central channel of the body? Some may say it is an attempt to find purusha, the ‘true self’ or atman, or to discover a connectedness of self with something universal and unchanging. Interestingly, those who lack or lose vestibular function often suffer from ‘depersonalisation’ 40
or a ‘lack of control of the self’. Perhaps working on balance and stillness, on finding the midline or central channel of the body, is also a form of self-realisation. Navigating the inner ear labyrinth might then improve our physical as well as our philosophical and psychological yoga practice. In The Mirror of Yoga, Richard Freeman opens the introduction with the 41
phrase, “Yoga begins with listening”. If we can listen with our inner ear, with our deep and primitive sense of balance, I think we will find ourselves connecting deeply: not only with our bodies but with our brains, our memories, and ourselves.
40 Smith & Darlington 2013
41 Freeman 2010
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