Chronic pain reorganizes the brain's default mode network (DMN). Using resting-state functional magnetic resonance imaging, patients with chronic back pain, complex regional pain syndrome, and knee osteoarthritis all showed reduced connectivity between the medial prefrontal cortex and posterior DMN regions, alongside increased connectivity to the insular cortex proportional to pain intensity. Multiple DMN regions, especially the medial prefrontal cortex, exhibited increased high-frequency oscillations and decreased phase locking with parietal attention-processing regions. Both phase and frequency changes correlated with pain duration in osteoarthritis and chronic back pain patients. These findings suggest chronic pain reflects maladaptive neural dynamics across different pain types.
The human brain generates coherent, subjective perceptions by distributing stimulus-specific information throughout the whole brain, not just in dedicated regions. Using fMRI, researchers found that information about a stimulus, such as a banana, is spread across the neocortex, subcortex, and cerebellum, even in voxels typically considered noise. These signals are influenced by sedation levels, linking them to perception rather than mere sensory encoding. The findings challenge the traditional view that perception arises from processing in isolated brain regions and suggest that widespread, stimulus-specific, and consciousness-dependent signals may underlie coherent subjective experiences.