Word class and context affect alpha-band oscillatory dynamics in an older population.
Word class and context affect alpha-band oscillatory dynamics in an older population.
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DOI：
10.3389/fpsyg.2012.00097
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发表时间：
2012
影响因子：
3.8
通讯作者：
Friedman RB
中科院分区：
文献类型：
--
作者：
Mellem MS;Bastiaansen MC;Pilgrim LK;Medvedev AV;Friedman RB
之前已经发现阅读开放类(OC)和封闭类(CC)词的振荡脑电动力学的差异(Bastiaansen等人，并被认为反映了这些词类之间的词汇-语义内容的差异)。其中，Theta频段(4-7 HZ)在词汇-语义提取中起着重要作用。我们测试了这种theta效应在年龄较大的受试者中是否很强。此外，我们考察了词的上下文如何调节两种不同类别词的提取基础的振荡动力学。年龄较大的参与者(平均年龄55岁)在记录他们的脑电时，阅读以句法正确的句子或以混乱的顺序呈现的单词(即混乱的句子)。我们进行了时频分析，以考察能量如何根据单词的上下文或类别而变化。我们观察到，与CC词相比，OC的阿尔法(8-12 HZ)频段在200-700 ms之间的功率下降更大，但只有在加扰的句子上下文中才是如此。我们没有观察到这两种情况之间的theta能力的差异。环境对0到700 毫秒之间的阿尔法和低贝塔(13-18 赫兹)频段产生影响。这些结果表明，之前在年轻参与者样本中观察到的词类对theta能力变化的影响在这个年长的人群中似乎并不是一个强有力的影响。虽然这是研究之间的间接比较，但它可能表明年龄对不同人群的单词提取动力学存在影响。此外，词类和语境之间的交互作用表明，单词提取机制与句子水平的理解机制在阿尔法频段上存在交互作用。
Differences in the oscillatory EEG dynamics of reading open class (OC) and closed class (CC) words have previously been found (Bastiaansen et al.,) and are thought to reflect differences in lexical-semantic content between these word classes. In particular, the theta-band (4–7 Hz) seems to play a prominent role in lexical-semantic retrieval. We tested whether this theta effect is robust in an older population of subjects. Additionally, we examined how the context of a word can modulate the oscillatory dynamics underlying retrieval for the two different classes of words. Older participants (mean age 55) read words presented in either syntactically correct sentences or in a scrambled order (“scrambled sentence”) while their EEG was recorded. We performed time–frequency analysis to examine how power varied based on the context or class of the word. We observed larger power decreases in the alpha (8–12 Hz) band between 200–700 ms for the OC compared to CC words, but this was true only for the scrambled sentence context. We did not observe differences in theta power between these conditions. Context exerted an effect on the alpha and low beta (13–18 Hz) bands between 0 and 700 ms. These results suggest that the previously observed word class effects on theta power changes in a younger participant sample do not seem to be a robust effect in this older population. Though this is an indirect comparison between studies, it may suggest the existence of aging effects on word retrieval dynamics for different populations. Additionally, the interaction between word class and context suggests that word retrieval mechanisms interact with sentence-level comprehension mechanisms in the alpha-band.
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影响因子：
5.3
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