Large-Scale Functional Brain Network Reorganization During Taoist Meditation.

Meditation produces a distinct, reversible mental state that reorganizes brain network hubs and connections without altering global network properties like small-worldness. Analyzing resting-state fMRI data from 18 Taoist meditators of varying expertise, the study found that during meditation, sensory cortex areas (primary visual and auditory cortices, temporopolar areas) showed decreased connectivity, while the thalamus and default mode network components (precuneus, posterior cingulate cortex) increased connectivity. Long-distance front-to-back connections increased, while right-left connections between homologous cortices decreased. These changes suggest that shifts in consciousness involve both topological and spatial reorganization of brain networks, with the anatomical pattern of integration being as important as its overall level.

Study at a glance

Abstract

Meditation induces a distinct and reversible mental state that provides insights into brain correlates of consciousness. We explored brain network changes related to meditation by graph theoretical analysis of resting-state functional magnetic resonance imaging data. Eighteen Taoist meditators with varying levels of expertise were scanned using a within-subjects counterbalanced design during resting and meditation states. State-related differences in network topology were measured globally and at the level of individual nodes and edges. Although measures of global network topology, such as small-worldness, were unchanged, meditation was characterized by an extensive and expertise-dependent reorganization of the hubs (highly connected nodes) and edges (functional connections). Areas of sensory cortex, especially the bilateral primary visual and auditory cortices, and the bilateral temporopolar areas, which had the highest degree (or connectivity) during the resting state, showed the biggest decrease during meditation. Conversely, bilateral thalamus and components of the default mode network, mainly the bilateral precuneus and posterior cingulate cortex, had low degree in the resting state but increased degree during meditation. Additionally, these changes in nodal degree were accompanied by reorganization of anatomical orientation of the edges. During meditation, long-distance longitudinal (antero-posterior) edges increased proportionally, whereas orthogonal long-distance transverse (right-left) edges connecting bilaterally homologous cortices decreased. Our findings suggest that transient changes in consciousness associated with meditation introduce convergent changes in the topological and spatial properties of brain functional networks, and the anatomical pattern of integration might be as important as the global level of integration when considering the network basis for human consciousness.