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Marieke van Vugt

Meditation and rational decisions (2)

Posterior insula activation in meditators Posterior insula activation in meditators Kirk et al (2011) Frontiers in Neuroscience

In the recent study on decision making in meditators that I wrote about before, the decision that meditators made was accompanied by a very different pattern of brain activity from controls. Upon receiving an unfair offer, meditators activated more of the right posterior insole and posterior parietal cortex, about which I have written before. The right insular activation would even predict whether the person was going to make an accept decision, and its activity correlated with the amount of self-reported mindfulness (scientists measure mindfulness with a questionnaire in this case, which is not perfect, but the best measure we have).

The insula has been associated with lots of things, including interoception. Also, the size of this brain region has also been shown to increase with meditation practice (Lazar et al, 2005). This was quite remarkable, because one would ordinarily expect that more rational behavior would be associated with more activation in the control regions of the brain: the dorsolateral prefrontal cortex. This was however not the case, this occurred only for the control subjects when they responded more rationally. 


When the control subjects did not respond rationally, they showed more activation of the precuneus and the anterior insole. The precuneus is also activated when you do a lot of mindwandering (see e.g., Christoff et al, 2009), and the authors speculate that these control subjects may in fact be playing out a lot of potential scenarios about the offers they receive: what Sogyal Rinpoche would call making a lot of stories. The goal of meditation is to reduce the amount of stories you make. The anterior insula (not to be confused with the posterior insole discussed earlier) has been associated with disgust and anticipation of negative events. Control participants' anterior insula activation could actually predict whether they were going to reject the offer (i.e., make an irrational decision), which was not the case for meditators. Of course that could be related to the fact that this region was simply not activating very much in meditators, in agreement with the idea that negative emotional circuits are simply less active in meditators. 


Control participants also showed stronger activation of the dorsal striatum in response to unfair offers than meditators. The striatum is part of the human reward circuit. This finding thus suggests that meditators process rewards quite differently from controls. This is in agreement with preliminary findings of some colleagues that meditators' stratal activation is much less strong to appetitive and aversive rewards (juice and quinine, respectively) than controls. In short, a lot of things seem to change in your brain when you start meditating. So we are not completely stuck with the brain we have: we can actually change it to some extent!