Posted: 09.04.2014 | by AMRA
The Default Mode Network (DMN) is a functional network of interconnected anatomical brain structures. DMN interconnected structures are typically activated during mind-wandering and deactivated during periods of mindful awareness. Prior research has shown that meditators often have increased DMN gray matter density and decreased DMN connectivity compared to non-meditators. “Connectivity” is the degree to which the different DMN regions work together in concert.
Wang et al. [Neuroscience] explored the relationship between DMN connectivity while undergoing functional Magnetic Resonance Imaging (fMRI) and trait mindfulness as measured by the Mindful Attention Awareness Scale in 245 Beijing college students. Participants were asked to relax with eyes closed and remain still while undergoing the fMRI scan, which is a mundane procedure that usually evokes mind-wandering and DMN activity.
The researchers found that greater connectivity between the thalamus and the posterior cingulate cortex — two important DMN-connected anatomical structures — was associated with lower mindfulness. The thalamus appeared to be the key structure driving this relationship. This makes sense, as the thalamus is a crucial structure in both the DMN and the ascending reticular activating system (ARAS) — a competing brain network that plays an important role in wakefulness, attention, and vigilance.
The authors suggest that one can think of the thalamus as a switch that shifts the brain back and forth between mindfulness and mind-wandering. The greater the interconnectivity between the thalamus and the other DMN structures, however, the harder it may be to achieve mindful focus on the present moment. The thalamus is itself a complex structure containing multiple nuclei, and future research is needed to specify which regions are most involved.
Wang, X., Xu, M., Song, Y., Li, X., Zhen, Z., Yang, Z., & Liu, J. (2014). The network property of the thalamus in the default mode network is correlated with trait mindfulness. Neuroscience, 278, 291-301.