Addiction biology
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Research on addiction suggests that emotional alterations play an essential role in the development, maintenance, relapse and treatment outcome of substance abuse disorders. Although many neuroimaging studies focussed on the neural response to conditioned stimuli, much less is known about the neural response to natural affective stimuli in this pathological population. Previous research has demonstrated an altered emotional experience and autonomic response to emotional stimuli using the International Affective Picture System (IAPS) in drug abusers. ⋯ However, compared with controls, the cocaine group showed a significant hypoactivation of the dorsal and ventral striatum (including the nucleus accumbens), thalamus, parietal cortex and dorso-medial prefrontal cortex (dmPFC) when processing pleasant pictures. The analysis of pleasant versus unpleasant stimuli suggested that between-group differences in the dmPFC and striatal activation may be attributed to arousal processing rather than valence. These results could reflect the neural basis for the reduced ability of cocaine-dependent subjects to experience pleasure by daily natural reinforcers, suggesting that these alterations in the emotion processing may play an important role in drug dependence, treatment and relapse.
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Abnormal cue reactivity is a central characteristic of addiction, associated with increased activity in motivation, attention and memory related brain circuits. In this neuroimaging study, cue reactivity in problem gamblers (PRG) was compared with cue reactivity in heavy smokers (HSM) and healthy controls (HC). A functional magnetic resonance imaging event-related cue reactivity paradigm, consisting of gambling, smoking-related and neutral pictures, was employed in 17 treatment-seeking non-smoking PRG, 18 non-gambling HSM, and 17 non-gambling and non-smoking HC. ⋯ Nicotine craving correlated with activation in left prefrontal and left amygdala when viewing smoking-related pictures in HSM. Increased regional responsiveness to gambling pictures in brain regions linked to motivation and visual processing is present in PRG, similar to neural mechanisms underlying cue reactivity in substance dependence. Increased brain activation in related fronto-limbic brain areas was present in HSM with higher FTND scores compared with HSM with lower FTND scores.