Moreno-López Laura, Perales José C, van Son Dana, Albein-Urios Natalia, Soriano-Mas Carles, Martinez-Gonzalez Jose M, Wiers Reinout W, Verdejo-García Antonio
Department of Personality, Evaluation and Psychological Treatment, Universidad de Granada, Spain.
Addict Biol. 2015 May;20(3):546-56. doi: 10.1111/adb.12143. Epub 2014 Apr 17.
Cocaine addiction involves persistent deficits to unlearn previously rewarded response options, potentially due to neuroadaptations in learning-sensitive regions. Cocaine-targeted prefrontal systems have been consistently associated with reinforcement learning and reversal deficits, but more recent interspecies research has raised awareness about the contribution of the cerebellum to cocaine addiction and reversal. We aimed at investigating the link between cocaine use, reversal learning and prefrontal, insula and cerebellar gray matter in cocaine-dependent individuals (CDIs) varying on levels of cocaine exposure in comparison with healthy controls (HCs). Twenty CDIs and 21 HCs performed a probabilistic reversal learning task (PRLT) and were subsequently scanned in a 3-Tesla magnetic resonance imaging scanner. In the PRLT, subjects progressively learn to respond to one predominantly reinforced stimulus, and then must learn to respond according to the opposite, previously irrelevant, stimulus-reward pairing. Performance measures were errors after reversal (reversal cost), and probability of maintaining response after errors. Voxel-based morphometry was conducted to investigate the association between gray matter volume in the regions of interest and cocaine use and PRLT performance. Severity of cocaine use correlated with gray matter volume reduction in the left cerebellum (lobule VIII), while greater reversal cost was correlated with gray matter volume reduction in a partially overlapping cluster (lobules VIIb and VIII). Right insula/inferior frontal gyrus correlated with probability of maintaining response after errors. Severity of cocaine use detrimentally impacted reversal learning and cerebellar gray matter.
可卡因成瘾涉及持续难以忘却先前得到奖励的反应选项，这可能是由于学习敏感区域的神经适应性变化所致。针对可卡因的前额叶系统一直与强化学习及逆转缺陷相关，但最近的跨物种研究提高了人们对小脑在可卡因成瘾及逆转中所起作用的认识。我们旨在研究可卡因依赖个体（CDIs）中可卡因使用、逆转学习与前额叶、脑岛及小脑灰质之间的联系，这些个体的可卡因暴露水平各不相同，并与健康对照者（HCs）进行比较。20名CDIs和21名HCs完成了一项概率性逆转学习任务（PRLT），随后在一台3特斯拉磁共振成像扫描仪中进行扫描。在PRLT中，受试者逐渐学会对一种主要得到强化的刺激做出反应，然后必须学会根据相反的、先前无关的刺激-奖励配对做出反应。性能指标为逆转后的错误（逆转成本）以及错误后维持反应的概率。采用基于体素的形态学测量来研究感兴趣区域的灰质体积与可卡因使用及PRLT性能之间的关联。可卡因使用的严重程度与左小脑（小叶VIII）的灰质体积减少相关，而更大的逆转成本与一个部分重叠的簇（小叶VIIb和VIII）中的灰质体积减少相关。右脑岛/额下回与错误后维持反应的概率相关。可卡因使用的严重程度对逆转学习和小脑灰质产生了不利影响。
