Noxious somatosensory stimulation affects the default mode of brain function: evidence from functional MR imaging.

PURPOSE: To investigate whether default mode network (DMN) spatial properties can be directly affected by pain, with a comparison of painful and nonpainful conditions.
MATERIALS AND METHODS: The authors performed a functional magnetic resonance (MR) imaging study, approved by the local institutional ethics committee, involving 10 healthy male subjects (age range, 18-45 years) who gave written informed consent. The subjects underwent two experimental sessions of median nerve electrical stimulation at painful and nonpainful levels. Independent component analysis of the functional MR imaging data was performed to determine the DMN spatiotemporal pattern. Group-level DMN connectivity maps for painful and nonpainful conditions were obtained (P < .001, corrected with false discovery rate). The contrast between the connectivity maps in the two conditions was also computed (P < .05, corrected with false discovery rate).
RESULTS: The DMN maintained its typical temporal properties but was subject to modifications in connectivity pattern during painful stimulation, affecting the brain areas associated with pain processing. Increased connectivity in painful conditions was found mainly in the left prefrontal cortex and posterior cingulate cortex-precuneus, and decreased connectivity was found in the lateral parietal cortex.
CONCLUSION: Study findings were in line with the impairments of the DMN reported in patients with chronic pain. They support the hypothesis that alteration of the DMN connectivity pattern localized in specific brain areas during acute pain, if repeated across time, might induce permanent changes that could disrupt the DMN functional architecture.