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).