Location, location: using functional magnetic resonance imaging to pinpoint brain differences relevant to stimulant use

Aims The purpose of this review is to summarize the neural substrate dysfunctions and disrupted cognitive, affective and experiential processes observed in methamphetamine and cocaine- dependent individuals. Methods We reviewed all publications in PubMed that conducted comparison studies between healthy volunteers and cocaine-, amphetamine- or methamphetamine- dependent individuals using functional magnetic resonance imaging. Results Stimulant dependence is characterized by a distributed alteration of functional activation to a number of experimental paradigms. Attenuated anterior and posterior cingulate activation, reduced inferior frontal and dorsolateral prefrontal cortex activation and altered posterior parietal activation point towards an inadequate demand-specific processing of information. Processes reported most consistently to be deficient in these functional neuroimaging studies include inhibitory control, executive functioning and decision-making. Conclusion One emerging theme is that stimulant-dependent individuals show specific, rather than generic, brain activation differences, i.e. instead of showing more or less brain activation regardless of task, they exhibit process-related brain activation differences that are consistent with a shift from context-specific, effortful processing to more stereotyped, habitual response generation.