Meditation-related changes in brain dynamics and structure were investigated by scanning experienced meditators and naive controls with MRI during rest and focused-attention meditation. A machine-learning approach showed that effective connectivity (causal relationships between brain regions) was more informative than functional or structural connectivity alone for distinguishing meditators from controls. The most informative effective-connectivity links involved several large-scale networks, predominantly in the left hemisphere. Anatomical differences were smaller but present: meditators had stronger structural connectivity between four left-hemisphere areas belonging to somatomotor, dorsal attention, subcortical, and visual networks. The findings suggest a mechanism linking brain structure and function underlying meditation.
A world champion free diver's brain activity and connectivity shift markedly during a 6.5-minute breath-hold. EEG shows increased alpha wave power and connectivity, with decreased delta band connectivity. fMRI reveals heightened connectivity within the default mode network and visual areas, but reduced connectivity in sensorimotor cortices. These changes overlap with some meditation-related brain signatures but also include unique features suggesting altered somatosensory integration. Self-reports indicate that elite free divers may achieve a state of sensory dissociation during prolonged apnea, reflecting their ability to adapt psychologically and physiologically to extreme breath-holding.