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Practical Neuroscience: Yoga and Mindfulness

Yoga and Mindfulness as Practical Neuroscience


The purpose of this article is to introduce you (in everyday language as much as possible) to the basic neuroscience behind why yoga helps us feel more at ease within ourselves and within the world around us.


Introduction


Yoga can often be viewed as a pseudo-science in ‘modern’ society, fortunately research in the field of neuroscience now provides rigorous scientific evidence for how yoga actually changes our brain and nervous systems functioning.


In summary:

  • Yoga increases GABA in the brain which blocks other neurotransmitters that cause us to feel anxious/stressed.

  • Yoga helps us access our parasympathetic nervous system allowing us to feel at ease.

  • Through neurogenesis yoga may decrease our brains response to stress and increase our perception of positive emotions.

  • Yoga may help us rewire our 'simulation map' that generates our self perceptions.

  • Yoga may enhance the structures of the brain that enable the mindfulness required to change our behaviours and responses.

Yogic practises increase GABA levels in the brain


To begin, Streeter et al, throughout a series of studies (2007, 2010, 2012, 2018 & 2020), found evidence that yogic practises increase GABA levels in the brain. Essentially, GABA is a neurotransmitter or very small molecule in the body that allows us to feel at ease. GABA literally blocks the other neurotransmitters that make us feel anxious, stressed or overly stimulated. Interestingly, Steeter et al (2020) suggests that GABA levels drop down over time so at least one yoga session per week is recommended to maintain an uplift in GABA.


Yoga practises increase parasympathetic drive


Streeter et al also found yoga practises help reinstate activity within the parasympathetic nervous system as our normal state (think feeling at ease, rest, recovery and social bonding) rather than our sympathetic nervous system (think ready for action/fight or flight response). The modern lifestyle does a good job of setting our sympathetic nervous system as our normal neutral state which leads many of us to miss out on feeling truly refreshed or at ease. Activating and toning the vagus nerve through specfic breathing methods, plays a key role in this.


Yoga can potentially enhance neurogenesis.


Neurogenesis means the birth of new brain pathways (neurons) in the brain. Neurogenesis occurs in 3 key areas;


The hippocampus (where memories are stored): Garner et al (2019) found that yoga intervention increased hippocampus density, and this is associated with decreased feelings of stress. Of note, many neurological diseases and long term stress are associated with a decrease in hippocampus density, probably due to sustained high levels of cortisol.


The olfactory bulb (where we register and process smell): Although no research has yet specifically looked at neurogenesis in the olfactory bulb related to yoga, it is interesting that Nasikagra Dristhi (nose tip gazing) is traditionally used in yoga (often to start a practise). The Bihar Yoga School (2002) state Nasikagra Dristhi is “an excellent technique for calming anger and disturbed states of mind”. From a neuroscience perspective the olfactory bulb has connections that wrap directly back and around the limbic system including the amygdala which processes fear and initiates our fight or flight response.


The amygdala (where fear is processed): Gotnik et al (2018), in a study of 3742 participants in Rotterdam, discovered long term yoga practises decreased the volume of the right amygdala which is associated with negative memories, aggression and stress a.k.a the drive to compete with others. Of note the left side of the amygdala is associated with our ability to remember positive emotions and empathise with others.


Interestingly, the participants who took part in more yoga and meditation practises actually reported higher levels of stress in everyday life; Gotnik et al suggest that this is actually due to greater awareness of their stress levels and that yoga and meditation practitioners are better able to access their left amygdala and so regulate their stress levels through positive emotions and empathy.


Two practical techniques for calming the amygdala’s fear responses noted by (Gotnik et al 2018) are breathing techniques which increase the length of the breath slowing down the breathing rate, for example soft ujjayi breathing, and also the mindfulness technique of labelling (and so acknowledging) emotions as they arise.


The role of BDNF in Neurogenesis


We should note that for neurogenesis to occur a substance called BDNF (brain-derived neurotrophic factor) needs to be present and higher levels of BDNF are desirable. For example, Naveen et al (2013) found that yoga intervention actually increased BDNF levels more than drugs alone in a sample of people with depression.


This does not mean ‘yoga’ is the only ‘miracle generator’ of BDNF since various other studies show different forms of exercise increase BDNF, however what this does suggest is that Yoga may require a movement based exercise component in order to be effective at generating BDNF.


Yoga and Mindfulness Practises May Allow us to Rewire our ‘Simulation Map’ of Self Perception


In a part of the brain called the insula there is a ‘simulation map’ which affects how we feel/perceive any given situation (Farb et al 2015). The ‘simulation map’ is a map of our own self-perception: We process actual physical and emotional experiences in the insula and come up with a ‘self perceived’ interpretation (simulation) of the event. The important thing here is that the insula’s simulation map is generated from all our past experiences, and so predisposes us to feeling/responding in a similar manner as before. Left to its own devices the insula may well ‘trap’ us in habitual behaviour.


So, the insula maps both physical and emotional experiences. The insula processes pain, pleasure, heat, cold, stretching, tensing, somatosensation (weight/texture of the body), heart rate, balance and emotion (Uddin et al 2017). However, the insula overlaps and blends physical and emotional experiences much more than we would commonly think during our everyday lives. Related to yoga this means that learning to stay with difficulty or discomfort in physical postures literally overlaps and also builds our ability to stay with difficult or uncomfortable emotional experiences. Likewise, learning to ‘find ease’ in varied challenging postures may also overlap, training us to ‘find ease’ in varied and challenging emotional situations.


From a neuroscience perspective there is still much to learn about the insula as it is very deep within the brain (Uddin et al 2017). However, it is very interesting that traditional yoga nidra techniques guide us to imagine and experience pairs of opposites. Note, above we said the insula perceives and maps heat and cold sensations. In yoga nidra there is a technique that asks us to imagine being very hot, then imagine being very cold and also cycle between them. Likewise, the insula maps how we feel the weight of the body, in yoga nidra there is also a technique that asks us to imagine feeling very heavy and then as light as a feather. From personal experience, with practise these pairs of opposites shift from pure imagination to actual physical experience.


What does all this mean practically?


Hart et al (2011), state that for becoming ‘liberated’ from behavioural responses and motivations that are based upon past experiences/conditioning (mapped in the insula), learning to directly experience one's stress response and also what triggers that stress response is vital. By cultivating the ability to stay with experiences in yoga and mindfulness, it is likely we develop the insights into our self that allow us to choose to act differently when faced with a potentially stressful situation.


Yoga prepares the prefrontal cortex for effective mindfulness!


To help understand the above we should briefly explore the Prefrontal Cortex (PFC) and Anterior Cingulate Cortex (ACC), which together with the Insular form most of the front part of the brain.


Afonso et al (2017) found that yoga may well preserve and even increase the size of the prefrontal cortex which usually gets thinner as we age. Afonso et al studied 21 older female (60+) yoga practitioners who had practised hatha yoga at least twice a week for at least 14 years, and found that in comparison to matched control participants, numerous areas in their prefrontal cortex were significantly larger. This is interesting as the prefrontal cortex allows rational and reflective thinking that enables us to consciously adjust how we behave - ‘‘mindfulness’ occurs in the prefrontal cortex.


The anterior cingulate cortex helps keep our attention focused. In many mental health disorders and stressful situations the anterior cingulate cortex struggles to shift its attention away from the immediate, normally uncomfortable, experience. This is where training the mindfulness abilities of the prefrontal cortex comes into play as the prefrontal cortex can actively guide the anterior cingulate cortex to attend to a different experience.


The prefrontal cortex has direct pathways to the amygdala (where fear is processed). This is a two way relationship meaning; activity in the prefrontal cortex can mediate our feelings of stress and fear but likewise, activity in the amygdala can mediate our ability to think rationally and reflect upon situations.


For our yoga and mindfulness practises this suggests that the prefrontal cortex should first be well developed/trained (i.e. through yoga practises which also help weaken the amgydala’s fear response) before mindfulness (which uses the prefrontal cortex to regulate our attention and fear responses) becomes effective (The Minded Institute 2020).



References


Afonso et al (2017). Greater cortical thickness in elderly female yoga practitioners—a cross-sectional study. Frontiers in Aging Neuroscience, 9, pp. 201.


Farb et al (2015). Interoception, contemplative practice, and health. Frontiers in Psychology, 6, pp. 763.


Garner M, Reith W & Krick C (2019). 10- week hatha yoga increases right hippocampal density compared to active and passive control groups: a controlled structural cMRI study. Journal of Neuroimaging Psychiatry Neurology, 4 (1) pp.1-11.


Goleman, D. (2008). Destructive emotions: a scientific dialogue with the dalai lama. New York City, Bantam Books.


Gotink et al (2018). Meditation and yoga practice are associated with smaller right amygdala volume: the Rotterdam study. Brain Imaging and Behaviour, 12 pp.1631–1639.


Hart, W. (2011). The art of living: Vipassana meditation: as taught by SN Goenka. Onalaska, Pariyatti.


Naveen, G H et al (2013). Positive therapeutic and neurotropic effects of yoga in depression: A comparative study. Indian journal of psychiatry 55 (3) pp.400-404.


Streeter C, C et al (2007). Yoga asana sessions increase brain GABA levels: a pilot study. The Journal of Alternative and Complementary Medicine, pp 419-426.


Streeter C, C et al (2010) Effects of yoga versus walking on mood, anxiety, and brain GABA levels: a randomized controlled MRS study. The Journal of Alternative and Complementary Medicine, 16 (11) pp.1145-1152


Streeter C, C et al (2012). Effects of yoga on the autonomic nervous system, gamma-aminobutyric-acid, and allostasis in epilepsy, depression, and post-traumatic stress disorder. Medical Hypotheses, 78 (5), pp 571 - 579.


Streeter C, C et al (2018). Effects of yoga on thalamic gamma-aminobutyric acid, mood and depression: analysis of two randomized controlled trials. Journal of Neuropsychiatry, 8 (6).


Streeter C, C et al (2020).Thalamic gamma aminobutyric acid level changes in major depressive disorder after a 12-week iyengar yoga and coherent breathing intervention. The Journal of Alternative and Complementary Medicine, 26 (3) pp.190-197.


The Minded Institute (2020). Yoga therapy for anxiety: resource. As presented by Heather Mason. CPD course 15th-19th June 2021.


The Bihar Yoga School (2002). Asana Pranayama Mudra Bandha. Author: Swami Satyananda Saraswati. Yoga Publications Trust, Mungar, Bihar, India.


Uddin et al (2017). Structure and function of the human insula. Journal of Clinical Neurophysiology, 34 (4) pp.300-306.



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