Addiction changes orbitofrontal gyrus function: involvement in response inhibition

We used the Stroop task as a measure of the ability to inhibit a prepotent response tendency and examined its association with relative glucose metabo lism in selected prefrontal brain regions in cocaine addicts, alcoholics, a nd controls (17 per group). Results revealed that for the substance abusers , higher orbitofrontal gyrus (OFG) activation was associated with lower con flict (higher score; r = 0.32, p < 0.05). For the controls, higher OFG acti vation was associated with higher conflict (lower score; r = -0.42, p < 0.0 5). Thus, at baseline, increased relative activation of the OFG is associat ed with worse performance in controls and better performance in substance a busers on the Stroop task, suggesting reversal of the role of the OFG as a function of addiction. NeuroReport 12:2595-2599 (C) 2001 Lippincott William s & Wilkins.