Long-term meditation practice is linked to structural changes in the brain. Magnetic resonance imaging of 20 experienced Insight meditation practitioners showed greater cortical thickness in regions involved in attention, interoception, and sensory processing, including the prefrontal cortex and right anterior insula, compared to matched controls. The difference in prefrontal thickness was most pronounced in older participants, suggesting meditation may counteract age-related cortical thinning. Thickness in two regions also correlated with meditation experience. These findings provide the first structural evidence that meditation practice can induce experience-dependent cortical plasticity.
Consciousness depends on both arousal (wakefulness) and awareness. While cortical networks for awareness are well studied, the subcortical networks supporting arousal are less understood. By combining ex vivo diffusion MRI, immunohistochemistry, and in vivo 7 Tesla functional MRI in three human brain specimens, the authors identified a default ascending arousal network (dAAN) in the brainstem, hypothalamus, thalamus, and basal forebrain. They mapped connections within the dAAN and between the dAAN and the cortical default mode network (DMN), suggesting a structural basis for integrating arousal and awareness. The data and methods are released to aid further mapping of human consciousness.