Task modulation of brain responses in visual word recognition as studied using EEG/MEG and fMRI.
Task modulation of brain responses in visual word recognition as studied using EEG/MEG and fMRI.
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DOI：
10.3389/fnhum.2013.00376
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发表时间：
2013
影响因子：
2.9
通讯作者：
Hauk O
中科院分区：
文献类型：
--
作者：
Chen Y;Davis MH;Pulvermüller F;Hauk O
任务需求是改变了我们从刺激中提取信息的方式，还是仅仅改变了我们利用这些信息进行决策的方式？为了回答视觉单词识别的这个问题，我们使用EEG/MEG以及fMRI来确定大脑对单词的激活受到任务要求调制的潜伏期范围和空间区域。我们在三个任务(词汇判断、语义判断、默读)中呈现了字母串，并在两个单独的实验中测量了EEG/MEG和fMRI的组合反应。EEG/MEG传感器的统计数据显示，最早的可靠任务效应出现在150ms左右，使用最小范数估计(MNE)定位于左侧颞叶下回、右侧颞叶前回和左侧中央前回。较晚的任务效应(250ms和480ms)出现在左侧颞中回和下回。我们的fMRI数据显示了左侧额叶下部、颞叶上后部和中央前皮质的任务效应。虽然fMRI和EEG/MEG定位之间有一定的对应关系，但差异占主导地位。我们认为，功能磁共振成像对我们的脑电/脑磁图数据中揭示的早期短暂过程可能不那么敏感。我们的结果表明，任务特定的过程在150ms就开始渗透到单词识别中，这表明早期的单词处理是灵活的，与决策息息相关。
Do task demands change the way we extract information from a stimulus, or only how we use this information for decision making? In order to answer this question for visual word recognition, we used EEG/MEG as well as fMRI to determine the latency ranges and spatial areas in which brain activation to words is modulated by task demands. We presented letter strings in three tasks (lexical decision, semantic decision, silent reading), and measured combined EEG/MEG as well as fMRI responses in two separate experiments. EEG/MEG sensor statistics revealed the earliest reliable task effects at around 150 ms, which were localized, using minimum norm estimates (MNE), to left inferior temporal, right anterior temporal and left precentral gyri. Later task effects (250 and 480 ms) occurred in left middle and inferior temporal gyri. Our fMRI data showed task effects in left inferior frontal, posterior superior temporal and precentral cortices. Although there was some correspondence between fMRI and EEG/MEG localizations, discrepancies predominated. We suggest that fMRI may be less sensitive to the early short-lived processes revealed in our EEG/MEG data. Our results indicate that task-specific processes start to penetrate word recognition already at 150 ms, suggesting that early word processing is flexible and intertwined with decision making.
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