PLEASURE AND PAIN: NUCLEUS ACCUMBENS FUNCTIONAL ARCHITECTURE IN ACUTE AND CHRONIC PAIN

Abstract

The nucleus accumbens (NAc) is a heterogenous hub involved in the motivational salience of rewarding and aversive stimuli, and in the aetiology of chronic back pain (CBP). Its role in responding to varying threats and noxious stimuli, as well as intrinsic differences in NAc subregion (shell and core) connectivity between healthy controls (HC) and CBP, remain elusive. The first part examines NAc activation to different noxious stimuli after uncertain, low, and high threat cues in 35 HC using task-fMRI. The NAc core preferentially activated to uncertain threats and to violations between expectations and reality. The second part elucidates reproducible NAc subregion connectivity differences between 75 CBP and 71 HC using rest-fMRI. CBP patients had NAc hyperconnectivity to prefrontal regions (NAc-dorsolateral prefrontal cortex) and hypoconnectivity to language/memory and salience regions. This thesis implicates the NAc as a major hub in aversive responding and highlights specific connections for CBP diagnostics and therapeutics.