Functional Reorganization of Reward- and Habit-Related Brain Networks in Addiction

Addiction is a significant health burden with a major impact on society. Its neural underpinnings have been extensively studied in animal experiments and human neuroimaging studies, which have demonstrated that during addiction various reorganizational processes hijack the reward and habit systems. Thus, subcortical and cortical brain regions become involved in pathological learning and maintenance of incentive values and automatized actions, which consequently contribute to the emergence and persistence of addiction. Reward-related processes that are affected predominantly during early stages of addiction comprise the ventral tegmental area, ventral and dorsomedial striatum, amygdala, hippocampus, orbitofrontal/medial prefrontal cortex, anterior cingulate cortex, and insula. Habit-related mechanisms are under the control of a more complex network including interconnections between the ventral tegmental area, ventral and dorsolateral striatum, parts of the amygdala, and cortical regions such as premotor and motor cortex, parietal and inferior/middle temporal cortex, as well as the cerebellum.