When we meditate, we start by calming and holding our mind. We aim to shift our mind’s focus toward the object of meditation—most simply, to the sensations accompanying the breath—and away from discursive, dull thought. The goal in this stage of practice, known as Shamata in Sanskrit, is to create space between ourselves and our very visceral experiences. Learning to better identify when our mind has wandered and to non-dramatically reorient ourselves is a supreme gift. This practice builds more awareness into our lives. In recent years, neuroscience has taken an interest in mind-wandering to better understand the architecture of the brain.
“Lay still, with your eyes closed, and do not think about any one thing” are common instructions for someone about to receive a functional Magnetic Resonance Imaging (fMRI) scan. An fMRI measures shifts in blood oxygenation caused by neuronal activity. Essentially, an fMRI provides a snapshot of the whole brain at millimeter-scale resolution every couple of seconds. As fMRI demonstrates, and as any meditator knows, our brain doesn’t become silent just because we are at rest. In fact, many distinct brain regions coherently fluctuate when we are not actively doing anything (what neuroscientists call the resting state). While the brain contains more than 100 billion neurons, different clusters of neurons that form separate networks become identifiable with fMRI. One network is particularly interesting from a Buddhist perspective: the Default-Mode Network (DMN).
The DMN was discovered after many separate experiments showed the same brain regions were de-activated when subjects performed an attention-demanding task (Raichle et al., 2001). After further examination, the DMN was found to be active during self-related thoughts concerning the past or future. Some scientists have aptly described this state as “mental time travel” (Østby et al., 2012). Thoughts of this nature can include, “I need to reply to that email later,” or, “I didn’t like that movie yesterday.” For this reason, the DMN is thought to be integral to the personal narrative or monologue we constantly identify with (Wang et al., 2018). Interestingly, the DMN is also engaged during social interactions, and this includes our understanding of others’ beliefs, desires, and emotions (Arioli et al., 2020).
Long-lasting effects in the brain related to behavioral change are referred to as neuroplasticity, which represents an exciting field of neuroscience. Experiments using fMRI have demonstrated that when trained meditation practitioners (~10,000 lifetime hours) are asked to meditate, they exhibit reduced DMN brain activity compared to novices also instructed to meditate (Brewer et al., 2011). Even when experts are not meditating, the DMN shows lower fluctuations (Berkovich-Ohana et al., 2016) and has reduced connectivity to particular brain regions heavily involved in emotional judgment (Taylor et al., 2013). The instruction when we start any Diamond Way meditation, to “let thoughts and feelings pass without evaluation,” may point towards the meaning behind this scientific result.
Training our awareness to recognize discursive thought and tune into the present moment is a general Buddhist principle. Changing the DMN is not the goal of Buddhist practice, of course, but the DMN’s association with mind-wandering and social-conceptual thought would suggest that this brain network should transform with meditative development, as recent fMRI studies indeed suggest. However, it would be an oversimplification of the Buddhist perspective to categorize all mind-wandering as dull; instead, I actually think Buddhists can effectively appreciate the freshness of a moment without any particular goal. But a key distinction here would be a yogi’s constant awareness of what is happening. This contrasts frequent and uninhibited distraction, or ‘mental time travel’, which many meditation-naive or novice practitioners encounter (including myself, as is evident in the figure!).
Diamond Way, or Vajrayana (Skt.) practice, radically transforms our conscious experience, and the DMN is likely only a small window in gauging that transformation. Many readers would attest that the Creation (Tib. Che Rim) and Completion (Tib. Dzog Rim) aspects of tantric Buddhist meditation push myriad buttons of perception. Still, the scientific outcomes referenced here are inspiring in that they demonstrate to practitioners, and also—importantly—to meditation skeptics, that one can consciously shape one’s brain each time one sits on the cushion.
References
Arioli, Maria, Claudia Gianelli, and Nicola Canessa. “Neural Representation of Social Concepts: a Coordinate-Based Meta-Analysis of FMRI Studies.” Brain Imaging and Behavior 40 (2020): 1-10. https://doi.org/10.1007/s11682-020-00384-6.
Berkovich-Ohana, Aviva, Michal Harel, Avital Hahamy, Amos Arieli, and Rafael Malach. “Alterations in Task-Induced Activity and Resting-State Fluctuations in Visual and DMN Areas Revealed in Long-Term Meditators.” NeuroImage 135 (2016): 125–34. https://doi.org/10.1016/j.neuroimage.2016.04.024.
Brewer, J. A., P. D. Worhunsky, J. R. Gray, Y.-Y. Tang, J. Weber, and H. Kober. “Meditation Experience Is Associated with Differences in Default Mode Network Activity and Connectivity.” Proceedings of the National Academy of Sciences 108, no. 50 (2011): 20254–59. https://doi.org/10.1073/pnas.1112029108.
Ostby, Y., K. B. Walhovd, C. K. Tamnes, H. Grydeland, L. T. Westlye, and A. M. Fjell. “Mental Time Travel and Default-Mode Network Functional Connectivity in the Developing Brain.” Proceedings of the National Academy of Sciences 109, no. 42 (2012): 16800–16804. https://doi.org/10.1073/pnas.1210627109.
Raichle, M. E., A. M. MacLeod, A. Z. Snyder, W. J. Powers, D. A. Gusnard, and G. L. Shulman. “A Default Mode of Brain Function.” Proceedings of the National Academy of Sciences 98, no. 2 (2001): 676–82. https://doi.org/10.1073/pnas.98.2.676.
Taylor, Véronique A., Véronique Daneault, Joshua Grant, Geneviève Scavone, Estelle Breton, Sébastien Roffe-Vidal, Jérôme Courtemanche, et al. “Impact of Meditation Training on the Default Mode Network during a Restful State.” Social Cognitive and Affective Neuroscience 8, no. 1 (2012): 4–14. https://doi.org/10.1093/scan/nsr087.
Wang, Hao-Ting, Danilo Bzdok, Daniel Margulies, Cameron Craddock, Michael Milham, Elizabeth Jefferies, and Jonathan Smallwood. “Patterns of Thought: Population Variation in the Associations between Large-Scale Network Organisation and Self-Reported Experiences at Rest.” NeuroImage 176 (2018): 518–27. https://doi.org/10.1016/j.neuroimage.2018.04.064.
