I used to think that the practice of “mindful meditation” was exclusively the preserve of yogis, Buddhists and New Age hippies fresh back from an extended voyage of self-discovery around Asia. If you’ve ever found yourself caught up in a conversation with an over-enthusiastic traveler fresh back from their adventures you’ll know what I mean. Such folk have usually undergone a wholesale transformation from fairly conventional individuals into barefoot, sandalwood-scented, Thai-dyed, hemp shirt and trousers wearing, bead bracelet bedecked eccentrics who preach the stupidity of capitalism and the supremacy of the compassionate mind-set at any and all available opportunities. My attitude has changed fundamentally in recent months.
A recent review paper (in Nature Reviews Neuroscience, no less) evaluating the flurry of scientific investigations into the possible benefits of practicing mindfulness that have accumulated over the past ten years or so, has given me a fresh perspective. To my surprise it turns out that there is plenty of early evidence attesting to “beneficial effects on physical and mental health; and cognitive performance.”
WHAT IS MINDFULNESS?
Mindfulness is actually a very simple concept to grasp, if only we’d give it a half chance. From the moment we wake to the moment we go back to sleep our minds are cluttered with innumerable thoughts.
These thoughts tend to focus on the past and the future: conversations, experiences and interactions that occurred in the past and hopes, ambitions, fears and other concerns regarding the future. Mindfulness encourages the development of attention directing and emotional regulating capacities that enable us to focus on the present moment. Ultimately, by getting in the habit of focusing on what we target with our conscious awareness, rather than just allowing ourselves to be buffeted by whatever stimuli, thoughts or feelings happen to flicker through our minds, we can achieve a greater self-awareness.
There are many different ways of achieving a mindful brain state but typically the beginner is encouraged to start by focusing on their breath. They are asked to breath deeply, in and out, right into the belly to ensure their diaphragm is being used to full effect. Whilst performing these simple actions they are regularly reminded to bring their attention back to their breath whenever the mind wanders elsewhere, to notice the cool air passing in through the nostrils on the inhale and the warm air passing out again on the exhale. After a few minutes of this, you are usually instructed to re-direct the focus of your attention on different body parts, moving systematically around the body. Notice the feeling of clothing on skin, upward pressure of the floor (or the chair) on your buttocks – move your mind’s eye from your toes, gradually up through the legs, into hips, up your back, across your shoulders and down your arms to your finger tips.
FOCUS AND RE-FOCUS YOUR MIND
When thoughts pop into your head, as they invariably will, the idea is not to block them or force them out, but simply to acknowledge them without engaging too deeply; focusing attention back on your breath, or touch sensations in a certain body part.
It sounds extremely simple (too straightforward to result in any meaningful benefits surely?!) but most of us are ingrained with deeply entrenched habits of thought such as worrying about events in the past or future or perpetually seeking some form of stimulation that it can take a while to achieve the goal of quiet contemplation of bodily sensations for more than 20 or 30 seconds at a time. But for those who stick at it – regularly, intensively and consistently over many weeks and months – and gradually build their ability to stay in this mindful state for 5, 15, 30, 60 mins at a time, a wide variety of benefits are achievable. And the latest neuroscience studies into mindfulness are homing in on what it going on inside the brain as a result of all this practice.
To find out about how mindfulness changes the brain please click here.
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In part 1 of this blog I broadly described the benefits of mindfulness and what it involves. Here I dig into the detail, outlining the parts of the brain that appear, on the basis of a recent review of many brain scanning studies, to be most consistently impacted by the regular practice of mindfulness.
NEUROPLASTICITY IN ACTION?
Using MRI scanning to focus on differences in the physical structure of brains has revealed that the anterior cingulate cortex (highlighted in yellow in the below image), often implicated in studies of attention, is physically thicker and the underlying white matter denser in practitioners of mindfulness who are highly experienced as opposed to those who are relatively inexperienced.
Moderate to severe stress is associated with high levels of circulating cortisol (a “stress” hormone). This is associated with increased density in the amygdala (highlighted in red in the below image) – a structure deep within the tips of the left and right temporal lobes and vital for orchestrating rapid responses to perceived danger. Decreased tissue density is observed within several prefrontal regions and the hippocampus – which also resides within the core of the temporal lobes – serving several memory-related functions and vital for many aspects of cognition. Regular practice of mindfulness appears to reverse this. Cognitive impairment is reduced and presumably an increase in synaptic connectivity accounts for the increase in tissue density within the hippocampal / prefrontal cortex. The enlarged amygdala shrink – presumably due to reductions in the number of synaptic connections between neurons in this region – which is also associated with a reduction in anxious feelings / the attenuation of heightened perception of threat, back down to normal levels.
The default mode network (DMN) describes a group of brain areas that are activated in MRI brain scanning studies when participants are “in between tasks”. At first these activations were thought to reflect the brain at “rest” or in “default mode.” After a few more years of research, during which this same set of activations cropped up under circumstances that couldn’t reasonably be described as “restful” the original conclusion was revised. Considering all the studies in which the DMN kicked into action it seemed much more likely that it relates instead to “mind-wandering.”
In the original studies, when the participant was instructed to “rest” they would invariably use this period to self-reflect or daydream about something completely unrelated to the experimental task (I certainly did when I volunteered for various MRI studies – it’s impossible not to – anyone that’s seen Ghostbusters should know that).
A couple of years ago when I conducted a series of interviews (British Neuroscience Conversations) with various big hitting neuroscientists at the British Neuroscience Association’s conference, neuropsychopharmacologist Prof David Nutt pointed out that, if our “ego” or the “self” lives anywhere in the brain the Default Mode Network is the best candidate.
The medial prefrontal cortex (labelled DMPFC for the dorsal/upper part and VMPFC for the ventral/lower part) and posterior cingulate cortex (PCC), i.e. the core DMN regions, were less active in experienced versus inexperienced mindfulness practitioners. As one of the primary aims of many mediation practices is to selflessly accept thoughts and feelings in a non-judgemental, compassionate way – the reduction in these neural correlates of “ego” may well reflect a degree of success in this endeavour.
So inspired have I been by these revelations of fairly solid early evidence attesting to a likely neuroplastic impact of regular practice of mindful meditation on brain areas involved in modulating attention, emotional responses and perhaps even ego that earlier in the year I went to Mykonos for a retreat to immerse myself properly (opening the invitation to anyone who faniced coming along).
Since then I’ve gone on to develop a #brainboost campaign for Weight Watchers in order to help tackle the obesity epidemic by getting people’s brains ready for healthier eating by practising mindful eating, performing a bit of daily brain training to boost their working memory and learning some simple brain hacks, all with a view to eating more strategically.
During my research for this project I came across a nice little book on mindful eating that I would highly recommend: it’s called Eating Mindfully by Susan Albers. Personally I find a lot of books on this topic extremely cringeworthy, but Susan Albers describes the practical tips on how to avoid mindless / emotional eating through mindfulness in a very straightforward manner.
My own book “Sort Your Brain Out” includes a chapter on the kind of foods and eating habits that are good and bad for the brain. In addition, I do a weekly science podcast available on iTunes, audioboom, libsyn and podbay, with the delectable Lliana Bird who presents every Fri and Sat nights on Radio X. And I regularly share the best of the day’s neuroscience breakthroughs on twitter (@drjacklewis).
If you take a quick peak in most neuroscience textbooks you will most likely be informed that the amygdala is a critical part of the emotion-generating limbic system, that it’s activation makes events more memorable and that it’s primary role is to trigger the fear response. However during the few days between Christmas and New Year I found myself writing two separate #braintweets that described a pair of recent studies that identified a positive correlation between the size of a person’s amygdalae and high-level brain functions that, on the face of it, have nothing to do with fear whatsoever: 1) a larger social network and 2) a conservative political persuation. Here I investigate how these seemingly incompatible findings about the amygdala all fit together. I argue that, tempting as it is to draw the facile conclusion that people with large amygdalae are more fearful in general, which makes them more likely to vote conservative and to nurture a large group of allies to protect themselves , in all likelihood this is probably not the case.
Why we think the amygdala does fear
It has been known for several decades that the amygdala, an almond-shaped cluster of highly interconnected brain cell nuclei deep within the inward facing part of the left and right temporal lobes, are very important in the generation of fear. Ever since fairly barbaric surgical procedures carried out in the 1930’s to see what happens when the temporal poles were removed (including the amygdalae) the most obvious consequence was that the animals lost their fear of the human experimenters. They also over-reacted to all stimuli, showed an increased propensity to exploring objects with their mouths, and became hypersexual, as well as becoming incapable of producing the standard usual responses to danger, such as freezing, increased heart rate, hair standing on end etc, that usually occur in response to an overpowering and unexpected occurance such as a loud bang.
Since then many brain imaging studies have gone on to demonstrate that the amygdala is also highly responsive to fearful facial expressions (Sato et al, 2010, for a recently published example). Presumably this is because if another human is scared, it is advantageous for us to also generate feelings of fear, thus encourage behaviours that might also help us to evade the fearsome agent. Interestingly the neural mechanisms involved in making you feel scared when you lay eyes on the face of a petrified individual implies a multi-step process that includes: 1) accurately identification the emotion that they are experiencing AND then 2) generating this emotion in your own mind. This quite possibly invokes the dual phenomena of expression mimickry and the facial feedback hypothesis: we all have a curious tendency to copy the facial expressions of the people around us and the proprioceptive detection of this facial expression is thought to then trigger the feelings and potentially life-saving behaviours associated with fear. A similar sequence of mechanisms is involved when you see a smiling face – you tend to smile yourself and the smile makes you feel happy.
Beyond fear – what else does the amygdala do?
An fMRI experiment I did during my PhD studies investigated which human brain areas were sensitive to the relative synchrony between visual and auditory stimuli. Despite there being nothing particularly emotional (and certainly not fearsome) about a pair of visual stimuli that each rotated synchronously with a different characteristic sound, to my surprise I discovered that this multisensory synchrony produced strong activation of the amygdala (unpublished observation). Reading deeper into the amygdala literature I soon discovered that far from being a single functional unit it is in fact a cluster of several different brain nuclei, each highly interconnected with a different groups of brain regions and also highly interconnected with each other. Meta-analyses of many different brain imaging studies revealed that the amygdala is activated in response to faces displaying a whole range of different emotions including positive emotions and not just negative emotions such as fear (Phan et al., 2002).
A recent publication has demonstrated a positive correlation between the size and complexity of a person’s social network and the size of their amygdalae (Bickart et al, 2010). The suggested explanation for this correlation is that “a larger amygdala might enable us to more effectively identify, learn about and recognize socioemotional cues”. No suggestion that, of the 58 people whose brains were scanned in this study, those with the larger amygdala were the biggest scaredy cats. The question of which of them were the most timid simply wasn’t asked.
Geraint Rees, Director of UCL’s Institute of Cognitive Neuroscience, speaking on a recent BBC radio show, described an experiment due to be published next year (assuming it passes the peer-review process) that observed a positive correlation between amygdalar volume and conservative political views. This would be a step forward from a recently published paper that indicated increased activation of the amygdala when politically-interested participants read statements that agreed with their own political views (Gozzi et al, 2010).
It is difficult to see how the results of all these different studies might fit together in terms of a universal theory of amygdala function but the most parsimonious explanation is that different amygdalar nuclei each fulfil different functional roles. Some nuclei directly influence the hypothalamus to orchestrate the increased heart rate, breathing rate and freezing behaviour characteristic of the fear response. Other nuclei well connected with visual and auditory brain areas may direct attention to multisensory phenomena that change simultaneously. And yet further subdivisions of this complex brain structure may be involved in learning and using the critical social cues that help us to form allegiances with other humans, both on a personal and political level.