Sobell Department of Motor Neuroscience and Movement Disorders, UCL, Institute of Neurology, Queen Square, London, WC1N3BG, United Kingdom.
Neuropsychologia. 2012 Jul;50(9):2176-86. doi: 10.1016/j.neuropsychologia.2012.05.021. Epub 2012 May 31.
In general, declarative learning is associated with the activation of the medial temporal lobes (MTL), while the basal ganglia (BG) are considered the substrate for procedural learning. More recently it has been demonstrated the distinction of these systems may not be as absolute as previously thought and that not only the explicit or implicit nature of the memory task alone is important for the distinction of MTL or BG systems. Nevertheless, patients with BG dysfunction - such as patients with Parkinson's disease (PD) or Huntington's disease (HD) - are considered to be impaired at implicit learning. However, a more recent study demonstrated that one implicit learning task, probabilistic classification learning (examples include the weather prediction (WPT) and Mr. Potato Head tasks) is only impaired in PD when it involves learning with corrective feedback (FB) but not when it involves learning in a paired associate (PA) manner, without feedback. Therefore, it has been argued that the presence of feedback rather than the implicit nature of these tasks determines whether or not the BG are recruited. As patients with HD as well as those with PD, have also been shown to be impaired on the standard FB based version of probabilistic classification learning, the question remains as to whether or not there is a similar selective deficit in FB but not PA based probabilistic classification learning in HD. 18 patients with early HD and 18 healthy controls completed FB and PA versions of the WPT task. Relative to controls, HD patients were selectively impaired at WPT learning with feedback. These findings are consistent with previous evidence from studies of probabilistic classification learning in PD. Unlike PD, selective deficits in WPT learning in HD cannot be attributed to the effects of dopaminergic medication and must be directly related to BG dysfunction; for instance even in early HD, only 50% of the neurons in the medial head of caudate remain. We conclude that the striatum is important for WPT learning with feedback. Our findings are consistent with imaging evidence showing recruitment of the caudate during FB based WPT learning, while the MTL is associated with PA based learning.
一般来说，陈述性学习与内侧颞叶（MTL）的激活有关，而基底神经节（BG）被认为是程序性学习的基础。最近的研究表明，这些系统的区别可能并不像以前想象的那样绝对，不仅记忆任务的明确或隐含性质对于 MTL 或 BG 系统的区别很重要。然而，基底神经节功能障碍的患者，如帕金森病（PD）或亨廷顿病（HD）患者，被认为在隐性学习方面存在障碍。然而，最近的一项研究表明，一项隐性学习任务，概率分类学习（例如天气预报（WPT）和土豆先生任务）仅在涉及具有校正反馈（FB）的学习时在 PD 中受到损害，但在涉及配对联想（PA）方式的学习时，没有反馈则不受影响。因此，有人认为，是否存在反馈而不是这些任务的隐性性质决定了 BG 是否被招募。由于 HD 患者以及 PD 患者在基于 FB 的标准概率分类学习中也表现出受损，因此仍存在一个问题，即是否存在类似的选择性缺陷，即在基于 FB 但不在基于 PA 的概率分类学习中存在选择性缺陷。18 名早期 HD 患者和 18 名健康对照组完成了 FB 和 PA 版本的 WPT 任务。与对照组相比，HD 患者在 WPT 学习中具有反馈时受到选择性损害。这些发现与 PD 中概率分类学习的先前研究证据一致。与 PD 不同，HD 患者在 WPT 学习中的选择性缺陷不能归因于多巴胺能药物的影响，必须与 BG 功能障碍直接相关；例如，即使在早期 HD 中，只有 50%的尾状核头部中间的神经元仍然存在。我们得出结论，纹状体对于具有反馈的 WPT 学习很重要。我们的研究结果与影像学证据一致，表明在基于 FB 的 WPT 学习期间募集了尾状核，而 MTL 与基于 PA 的学习相关。
