Brennan Jonathan, Lignos Constantine, Embick David, Roberts Timothy P L
University of Michigan, Department of Linguistics, United States.
University of Pennsylvania, Department of Linguistics, United States; The Children's Hospital of Philadelphia, Radiology, United States.
Brain Lang. 2014 Jun;133:39-46. doi: 10.1016/j.bandl.2014.03.006. Epub 2014 Apr 24.
Lexical access during speech comprehension comprises numerous computations, including activation, competition, and selection. The spatio-temporal profile of these processes involves neural activity in peri-auditory cortices at least as early as 200 ms after stimulation. Their oscillatory dynamics are less well understood, although reports link alpha band de-synchronization with lexical processing. We used magnetoencephalography (MEG) to examine whether these alpha-related oscillations reflect the speed of lexical access, as would be predicted if they index lexical activation. In an auditory semantic priming protocol, monosyllabic nouns were presented while participants performed a lexical decision task. Spatially-localizing beamforming was used to examine spectro-temporal effects in left and right auditory cortex time-locked to target word onset. Alpha and beta de-synchronization (10-20 Hz ERD) was attenuated for words following a related prime compared to an unrelated prime beginning about 270 ms after stimulus onset. This timing is consistent with how information about word identity unfolds incrementally in speech, quantified in information-theoretic terms. These findings suggest that alpha de-synchronization during auditory word processing is associated with early stages of lexical access.
言语理解过程中的词汇通达包含众多计算过程，包括激活、竞争和选择。这些过程的时空特征至少在刺激后200毫秒就涉及到听觉周围皮层的神经活动。尽管有报告将阿尔法波段去同步化与词汇加工联系起来，但它们的振荡动力学仍不太为人所理解。我们使用脑磁图（MEG）来研究这些与阿尔法相关的振荡是否反映了词汇通达的速度，就像如果它们索引词汇激活所预测的那样。在一个听觉语义启动实验中，呈现单音节名词的同时让参与者执行词汇判断任务。使用空间定位波束形成来检查与目标词起始时间锁定的左右听觉皮层中的频谱时间效应。与无关启动词之后的单词相比，相关启动词之后的单词在刺激开始后约270毫秒开始，阿尔法和贝塔去同步化（10 - 20赫兹事件相关去同步化）减弱。这个时间与词汇身份信息在言语中如何逐步展开一致，这是从信息论角度量化的。这些发现表明，听觉单词加工过程中的阿尔法去同步化与词汇通达的早期阶段相关。
