Mahlberg Justin, Haber Paul, Morley Kirsten, Weidemann Gabrielle, Hogarth Lee, Beck Kevin D, Myers Catherine E, Moustafa Ahmed A
School of Social Sciences and Psychology, Western Sydney University, Locked Bag 1797, Penrith, Sydney, NSW, 2751, Australia.
NHMRC Centre of Research Excellence in Mental Health and Substance Use, Discipline of Addiction Medicine, Central Clinical School, The University of Sydney, Sydney, NSW, Australia.
Exp Brain Res. 2017 Oct;235(10):3153-3162. doi: 10.1007/s00221-017-5046-9. Epub 2017 Jul 27.
Substance dependence is thought to be mediated by abnormalities in cognitive abilities, but how this impacts decision-making remains unclear. This study aimed to test whether people who are opiate dependent differed from never-dependent controls in learning from reward and punishment or in the generalization of learning to novel conditions. Participants with opiate dependency consisted of 21 people who were outpatients in a methadone maintenance program; the control group consisted of 21 healthy participants with no histories of substance abuse. Subjects completed a computer-based task that involved two phases: the training phase involved participants being presented with compound stimulus (a shape and color) in each trial, with the goal of learning which compounds to 'pick' for rewards or 'skip' to avoid punishment. The test phase involved a transfer test, where stimuli from the first phase were combined together to form novel compounds without feedback. The control group demonstrated fewer errors compared to opiate-dependent individuals during the training phase. In the test phase, controls used prior knowledge of both shapes and colors in responding; however, opiate-dependent individuals used shapes but did not use their knowledge of color to modulate responding. When performance during training was equated in the groups using a learning threshold, this difference between groups on the generalization test remained. A deficit in learning generalization might be indicative of group differences in learning strategies in operation during training; however, future work is necessary to uncover the specific neural substrates in action during transfer tasks, and to determine the effects of acute methadone dosage on decision-making.
物质依赖被认为是由认知能力异常介导的，但这如何影响决策仍不清楚。本研究旨在测试阿片类药物依赖者在从奖励和惩罚中学习或在将学习推广到新情境方面是否与从未依赖者存在差异。阿片类药物依赖参与者包括21名在美沙酮维持治疗项目中的门诊患者；对照组由21名无药物滥用史的健康参与者组成。受试者完成一项基于计算机的任务，该任务包括两个阶段：训练阶段要求参与者在每次试验中看到复合刺激（一种形状和颜色），目标是学习选择哪些化合物以获得奖励或跳过哪些以避免惩罚。测试阶段包括一次迁移测试，其中将第一阶段的刺激组合在一起形成新的化合物且无反馈。在训练阶段，对照组的错误比阿片类药物依赖个体少。在测试阶段，对照组在反应中利用了形状和颜色的先验知识；然而，阿片类药物依赖个体利用了形状，但没有利用颜色知识来调节反应。当使用学习阈值使各组在训练期间的表现相等时，各组在泛化测试中的这种差异仍然存在。学习泛化缺陷可能表明训练期间操作的学习策略存在组间差异；然而，未来有必要开展工作以揭示迁移任务期间起作用的具体神经基质，并确定急性美沙酮剂量对决策的影响。
