Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
Psychiatry Res. 2011 Jan 30;191(1):51-9. doi: 10.1016/j.pscychresns.2010.10.002. Epub 2010 Dec 9.
Chronic marijuana users (MJ Users) perform poorly on the Iowa Gambling Task (IGT), a complex decision-making task in which monetary wins and losses guide strategy development. This functional magnetic resonance imaging (MRI) study sought to determine if the poor performance of MJ Users was related to differences in brain activity while evaluating wins and losses during the strategy development phase of the IGT. MJ Users (16) and Controls (16) performed a modified IGT in an MRI scanner. Performance was tracked and functional activity in response to early wins and losses was examined. While the MJ Users continued to perform poorly at the end of the task, there was no difference in group performance during the initial strategy development phase. During this phase, before the emergence of behavioral differences, Controls exhibited significantly greater activity in response to losses in the anterior cingulate cortex, medial frontal cortex, precuneus, superior parietal lobe, occipital lobe and cerebellum as compared to MJ Users. Furthermore, in Controls, but not MJ Users, the functional response to losses in the anterior cingulate cortex, ventral medial prefrontal cortex and rostral prefrontal cortex positively correlated with performance over time. These data suggest MJ Users are less sensitive to negative feedback during strategy development.
慢性大麻使用者（MJ 用户）在“爱荷华赌博任务”（IGT）中表现不佳，IGT 是一项复杂的决策任务，其中金钱的输赢会指导策略的制定。这项功能性磁共振成像（fMRI）研究旨在确定 MJ 用户的表现不佳是否与他们在评估 IGT 策略制定阶段的输赢时大脑活动的差异有关。16 名 MJ 用户和 16 名对照组在 MRI 扫描仪中完成了改良的 IGT。跟踪了他们的表现，并检查了对早期输赢的功能活动的反应。虽然在任务结束时，MJ 用户的表现仍然很差，但在初始策略制定阶段，两组的表现没有差异。在这个阶段，在行为差异出现之前，与 MJ 用户相比，对照组在前扣带皮层、内侧前额叶皮层、楔前叶、顶叶上回、枕叶和小脑对损失的反应表现出明显更大的活动。此外，在对照组中，但不是在 MJ 用户中，前扣带皮层、腹内侧前额叶皮层和额前皮质的损失的功能反应与随着时间推移的表现呈正相关。这些数据表明，在策略制定过程中，MJ 用户对负面反馈的敏感性较低。
