Prefrontal regions supporting spontaneous and directed application of verbal learning strategies - Evidence from PET
Prefrontal regions supporting spontaneous and directed application of verbal learning strategies - Evidence from PET
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DOI：
10.1093/brain/124.1.219
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发表时间：
2001-01-01
期刊：
影响因子：
14.5
通讯作者：
Rauch, SL
中科院分区：
文献类型：
--
作者：
Savage, CR;Deckersbach, T;Rauch, SL
前额叶皮层与策略记忆过程有关，包括使用语义组织策略促进情景学习的能力。这些策略的一个重要特征是它们在新的或模糊的情况下应用的方式--在非结构化的环境中自发地启动有效策略的失败是额叶障碍患者的中心认知缺陷。本研究采用PET和言语编码范式，在三种编码条件下（自发、定向和无关）考察了策略记忆。在自发条件下，受试者听到24个单词，这些单词在四个类别中相关，但顺序混合，并且他们事先没有被告知这种结构。因此，任何语义重组都是由主体自发发起的。在定向条件下，受试者得到了一个不同的24个相关单词的列表，并明确指示注意关系，并在脑海中将相关单词组合在一起以提高记忆力。不相关的列表由24个不相关的单词组成。行为的措施包括语义聚类，评估积极重组的单词到语义类别在自由回忆。在分级PET对比（定向>自发>无关）中，在左下前额叶皮层（额下回）和左背外侧前额叶皮层（额中回）中发现了两种不同的激活，对应于在行为数据中观察到的语义聚类水平。在第一个自发条件下的其他协变量分析表明，眶额皮质（OFC）中的血液如何与即时自由回忆过程中的语义聚类分数密切相关。因此，在编码过程中，OFC中的血液如何预测哪些受试者在自由回忆时会自发地启动有效的策略。我们的研究结果表明，眶额皮层执行一个重要的，以前未被赞赏的，在战略记忆中的作用，支持早期动员有效的行为策略，在新的或模糊的情况。一旦启动，左前额叶皮层的外侧区域控制言语语义组织。
The prefrontal cortex has been implicated in strategic memory processes, including the ability to use semantic organizational strategies to facilitate episodic learning. An important feature of these strategies is the way they are applied in novel or ambiguous situations-failure to initiate effective strategies spontaneously in unstructured settings is a central cognitive deficit in patients with frontal lobe disorders. The current study examined strategic memory with PET and a verbal encoding paradigm that manipulated semantic organization in three encoding conditions: spontaneous, directed and unrelated. During the spontaneous condition, subjects heard 24 words that were related in four categories but presented in mixed order, and they were not informed of this structure beforehand. Any semantic reorganization was, therefore, initiated spontaneously by the subject. In the directed condition, subjects were given a different list of 24 related words and explicitly instructed to notice relationships and mentally group related words together to improve memory. The unrelated list consisted of 24 unrelated words. Behavioural measures included semantic clustering, which assessed active regrouping of words into semantic categories during free recall. In graded PET contrasts (directed > spontaneous > unrelated), two distinct activations were found in left inferior prefrontal cortex (inferior frontal gyrus) and left dorsolateral prefrontal cortex (middle frontal gyrus), corresponding to levels of semantic clustering observed in the behavioural data. Additional covariate analyses in the first spontaneous condition indicated that blood how in orbitofrontal cortex (OFC) was strongly correlated with semantic clustering scores during immediate free recall. Thus, blood how in OFC during encoding predicted which subjects would spontaneously initiate effective strategies during free recall. Our findings indicate that OFC performs an important, and previously unappreciated, role in strategic memory by supporting the early mobilization of effective behavioural strategies in novel or ambiguous situations. Once initiated, lateral regions of left prefrontal cortex control verbal semantic organization.