Meditation-Induced Effects on Whole-Brain Structural and Effective Connectivity

Abstract

In the past decades, there has been a growing scientific interest in characterizing neural correlates of meditation training. Nonetheless, the mechanisms underlying meditation remain elusive. In the present work, we investigated meditation-related changes in structural and functional connectivities (SC and FC, respectively). For this purpose, we scanned experienced meditators and control (naive) subjects using magnetic resonance imaging (MRI) to acquire structural and functional data during two conditions, resting-state and meditation (focused attention on breathing). In this way, we aimed to characterize and distinguish both short-term and long-term modifications in the brain's structure and function. First, we performed a network-based analysis of anatomical connectivity. Then, to analyze the fMRI data, we calculated whole-brain effective connectivity (EC) estimates, relying on a dynamical network model to replicate BOLD signals' spatio-temporal structure, akin to FC with lagged correlations. We compared the estimated EC, FC, and SC links as features to train classifiers to predict behavioral conditions and group identity. The whole-brain SC analysis revealed strengthened anatomical connectivity across large-scale networks for meditators compared to controls. We found that differences in SC were reflected in the functional domain as well. We demonstrated through a machine-learning approach that EC features were more informative than FC and SC solely. Moreover, we showed that the most informative EC links that discriminated between meditators and controls involved the same large-scale networks previously found to have increased anatomical connectivity. Overall, the results of our whole-brain model-based approach revealed a mechanism underlying meditation by providing causal relationships at the structure-function level.

Spectral dynamic causal modeling of mindfulness, mind-wandering, and resting-state in the triple network using fMRI

“…Many previous studies have shown a relationship between mindfulness scores and functional connectivity of the lCEN and salience network, but not the rCEN [19,20]. A more recent study demonstrated that the insular region belonging to the salience network received signals from the lateral PFC (part of CEN), which allowed discriminating meditators from controls during mindfulness [21]. The right dorsolateral PFC (dlPFC; part of CEN) has been identified as the primary agent involved in the control of episodic retrieval, whereas the left dlPFC has been discovered as one of its key functions in modifying cognitive control functions [22].…”