(science)多巴胺帮助我们从错误中学习

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多巴胺帮助我们从错误中学习[img=http://china.sciencemag.org/china/icons/back.gif][To top][/img]一项来自德国的研究揭示，大脑中影响多巴胺信号发生的一个基因变异看来削弱人们从他们犯的错误中学习的能力。这些研究人员提出，他们的发现也许能帮助解释为什么这个被称为“等位基因”的变异过去被发现与上瘾和强迫行为有关。这个名为A1的等位基因与大脑中某种多巴胺受体密度低相关联。Tilmann A. Klein和同事比较了两组健康的男性，一组带有等位基因A1，另一组没有这个等位基因。研究人员让这些自愿受试者看随机出现的符号对，他们需要根据在每次选择后得到的正面或负面的反馈来判断应该选哪个符号。带有A1等位基因的志愿者学习避免带来负面后果符号的成功率比另一组的人低，意味着他们比另一组人对负反馈的响应低。功能MRI研究也支持这一结果，A1等位基因携带者学习避免错误能力的降低伴随着大脑中一个已知的监控负面后果区域中降低的活性。Klein 说，需要有更多的研究来确定这些结果与现实世界情况的联系。
英文摘要：Genetically Determined Differences in Learning from Errors,Tilmann A. Klein, Jane Neumann, Martin Reuter, Jürgen Hennig, el al.
Genetically Determined Differences in Learning from ErrorsTilmann A. Klein,1* Jane Neumann,1 Martin Reuter,2 Jürgen Hennig,3 D. Yves von Cramon,1,4 Markus Ullsperger1,4*
The role of dopamine in monitoring negative action outcomes and feedback-based learning was tested in a neuroimaging study in humans grouped according to the dopamine D2 receptor gene polymorphism DRD2-TAQ-IA. In a probabilistic learning task, A1-allele carriers with reduced dopamine D2 receptor densities learned to avoid actions with negative consequences less efficiently. Their posterior medial frontal cortex (pMFC), involved in feedback monitoring, responded less to negative feedback than others' did. Dynamically changing interactions between pMFC and hippocampus found to underlie feedback-based learning were reduced in A1-allele carriers. This demonstrates that learning from errors requires dopaminergic signaling. Dopamine D2 receptor reduction seems to decrease sensitivity to negative action consequences, which may explain an increased risk of developing addictive behaviors in A1-allele carriers. [size=-1]1 Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.
2 University of Bonn, Bonn, Germany.
3 University of Giessen, Giessen, Germany.
4 Max Planck Institute for Neurological Research, Cologne, Germany.