Midcingulate Cortical Activations Interrelate Chronic Craving and Physiological Responses to Negative Emotions in Cocaine Addiction.

Background: Negative emotions precipitate drug craving. Individuals vary in how they engage in negative emotions, as may be reflected in physiological arousal elicited by the emotions. It remains unclear whether physiological responses to negative emotions relate to cocaine craving and how regional brain activations support this relationship.

Methods: We examined brain activation and skin conductance responses (SCRs) among 40 cocaine-dependent (CD) subjects and 37 healthy control subjects during exposure to negative-emotional and neutral images. Imaging and SCR data were processed with published routines, and the results were evaluated at a corrected threshold.

Results: Relative to control subjects, CD subjects showed increased activation in the hippocampus, inferior parietal gyrus, and caudate in response to negative-emotional versus neutral images. CD subjects relative to control subjects showed diminished SCR to negative-emotional versus neutral images, and the difference (SCR) was positively correlated with chronic craving, as evaluated by the Cocaine Craving Questionnaire, and craving rating (negative-emotional - neutral), in CD subjects. Activations of the midcingulate cortex (MCC) were positively correlated with both chronic cocaine craving and SCR and completely mediated the correlation between chronic cocaine craving and SCR. Further, path analyses suggested a directional influence of SCR on craving rating (negative-emotional - neutral): chronic craving → MCC activation → SCR → craving rating.

Conclusions: CD subjects demonstrate hypoactive SCRs to negative emotions. Less diminution of SCR is associated with higher cocaine craving and MCC response to negative emotions. A hub of the limbic motor circuit, the MCC may translate chronic cocaine craving into physiological responses that precipitate cocaine seeking.