Functional and effective connectivity in mindfulness meditation

Mindfulness practice is frequently associated to changes into subjective evaluation of own cognitive and sensorial experience. Here we acquired resting-state fMRI data from two groups of healthy subjects who participated into an 8-weeks MBSR training or a waiting list program. Data from both a free wandering (FW) and a focusing on breathing (FB.) state have been acquired before and after the MBSR course. While the comparison between pre-post FB scans didn't show significant results, FW scans comparison highlighted a decrease of right putamen local connectivity in response to MBSR experience, expression of an intra-regional diminishing of spontaneous activity. Moreover, a whole-brain effective connectivity analysis (Granger causality), performed using putamen significant cluster as seed region, shows an increased inhibitory influence played by bilateral anterior cingulate cortex (ACC), a well-known site for cognitive control over painful sensation, error monitoring and emotional control. Our results suggest an increased modulation of ACC over ventral striatum after mindfulness training, with a possible cascade effect involving other striatum structures and finally resulting in thalamus inhibition during the rest. Considering recent evidence about putamen role in subjective pain evaluation, this cortical inhibition over striatum structures might explain mindfulness efficacy in pain modulation, suggesting a plausible new pain-related circuit which should be explored directly under painful stimulation.