Anterior cingulate cortex connectivity is associated with suppression of behavior in a rat model of chronic pain

Abstract

A cardinal feature of persistent pain that follows injury is a general suppression of behavior, in which motivation is inhibited in a way that promotes energy conservation and recuperation. Across species, the anterior cingulate cortex (ACC) is associated with the motivational aspects of phasic pain, but whether it mediates motivational functions in persistent pain is less clear. Using burrowing behavior as an marker of non-specific motivated behavior in rodents, we studied the suppression of burrowing following painful CFA or control injection into the right knee-joint of 37 rats (18 with pain), and examined associated neural connectivity with ultra-high-field resting state functional MRI. We found that connectivity between ACC and the subcortex correlated with the reduction in burrowing behavior observed following the pain manipulation. In a full replication study we confirmed these findings in a group of 44 rats (23 with pain). Across both datasets, reduced burrowing was assosciated with increased connectivity between ACC and subcortical structures including hypothalamic/preoptic nuclei and the bed nucleus of the stria terminalis. Together, the findings implicate ACC connectivity as a robust correlate of the motivational aspect of persistent pain in rodents.