Dynamical properties of BOLD activity from the ventral posteromedial cortex associated with meditation and attentional skills

Neuroimaging data suggest a link between the spontaneous production of thoughts during wakeful rest and slow fluctuations of activity in the default mode network (DMN), a set of brain regions with high basal metabolism and a major neural hub in the ventral posteromedial cortex (vPMC). Meta-awareness and regulation of mind-wandering are core cognitive components of most contemplative practices and to study their impact on DMN activity we collected functional MRI (fMRI) data from a cohort of experienced Zen meditators and meditation-naive controls engaging in a basic attention-to-breathing protocol. We observed a significant group difference in the skewness of the fMRI blood-oxygen level dependent (BOLD) signal from the vPMC, suggesting that the relative incidence of states of elevated vPMC activity was lower in meditators; furthermore, the same parameter was significantly correlated with performance on a rapid visual information processing (RVIP) test for sustained attentionconducted outside the scanner. Finally, a functional connectivity (fc) analysis with the vPMC seed revealed a significant association of RVIP performance and the degree of temporal correlation between vPMC and the right temporo-parietal junction (TPJ),a region strongly implicated in stimulus-triggered reorienting of attention. Taken together, these findings suggest that the vPMC BOLD signal skewness and the temporal relationship of vPMC and TPJ activities reflect the dynamic tension between mind-wandering, meta-awareness, and directed attention, and may represent a use-ful endophenotype for studying individual differences in attentional abilities and the impairment of the latter in specific clinical conditions.