Influence of meditation on anti-correlated networks in the brain.

The human cortex is organized into two broad systems: an extrinsic system that responds to external stimuli and tasks, and an intrinsic system linked to internal, self-related experiences. These systems typically show anti-correlated activity, even at rest. This experiment tested whether meditation can alter that competition. Participants either fixated without meditation or practiced non-dual awareness or focused attention meditations. Anti-correlation between the extrinsic and intrinsic systems was stronger during focused attention and weaker during non-dual awareness compared to fixation. Correlations within each system did not change. The results indicate that the anti-correlation between these systems is not fixed and that different meditation practices can modulate this functional brain organization in distinct ways.

Study at a glance

Abstract

Human experiences can be broadly divided into those that are external and related to interaction with the environment, and experiences that are internal and self-related. The cerebral cortex appears to be divided into two corresponding systems: an "extrinsic" system composed of brain areas that respond more to external stimuli and tasks and an "intrinsic" system composed of brain areas that respond less to external stimuli and tasks. These two broad brain systems seem to compete with each other, such that their activity levels over time is usually anti-correlated, even when subjects are "at rest" and not performing any task. This study used meditation as an experimental manipulation to test whether this competition (anti-correlation) can be modulated by cognitive strategy. Participants either fixated without meditation (fixation), or engaged in non-dual awareness (NDA) or focused attention (FA) meditations. We computed inter-area correlations ("functional connectivity") between pairs of brain regions within each system, and between the entire extrinsic and intrinsic systems. Anti-correlation between extrinsic vs. intrinsic systems was stronger during FA meditation and weaker during NDA meditation in comparison to fixation (without mediation). However, correlation between areas within each system did not change across conditions. These results suggest that the anti-correlation found between extrinsic and intrinsic systems is not an immutable property of brain organization and that practicing different forms of meditation can modulate this gross functional organization in profoundly different ways.