fMRI-constrained source analysis reveals early top-down modulations of interference processing using a flanker task
fMRI-constrained source analysis reveals early top-down modulations of interference processing using a flanker task
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DOI：
10.1016/j.neuroimage.2016.05.036
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发表时间：
2016-08
期刊：
影响因子：
5.7
通讯作者：
J. Siemann;M. Herrmann;Daniela Galashan
中科院分区：
文献类型：
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作者：
J. Siemann;M. Herrmann;Daniela Galashan
通常情况下，不一致的侧翼刺激会引发冲突加工，而一致的侧翼刺激会促进任务执行。各种行为研究报告称，在正确定向的选择性注意下，冲突处理能力有所改善，甚至完全消失。在这项研究中，我们试图重新研究这些行为效应，并利用脑电(EEG)的高时间分辨率和功能磁共振成像(FMRI)的空间分辨率相结合的优势，解开注意线索效应背后的神经元活动模式。每种方法在不同的会话中获得了来自20名参与者的数据。我们预计冲突相关的N200事件相关电位(ERP)成分和与侧翼加工相关的区域将显示有效性特定的调制。此外，我们还使用fMRI受限来源分析方法考察了线索侧翼加工过程中的时空动态。在ERP数据中，我们发现不同效度水平之间在侧翼加工过程中的早期差异。对于不一致刺激的早期中央-顶叶相对正向仅在N200时间窗口内的有效提示下发生，而随后的额叶-中央负向仅发生于无效线索干扰处理。来源分析还指出，这些影响的神经生成器是分开的。视觉区域的区域来源在有效线索的情况下参与冲突加工，而前扣带回的区域来源似乎在无效线索的情况下对事件相关电位的差异有贡献。此外，ACC和中央前回表现出早期和晚期的一致性相关活动差异，但提示无效。我们讨论的第一个效应反映了冲突检测和反应激活，而后者更可能来自反应竞争中的冲突监测和控制过程。
Usually, incongruent flanker stimuli provoke conflict processing whereas congruent flankers should facilitate task performance. Various behavioral studies reported improved or even absent conflict processing with correctly oriented selective attention. In the present study we attempted to reinvestigate these behavioral effects and to disentangle neuronal activity patterns underlying the attentional cueing effect taking advantage of a combination of the high temporal resolution of Electroencephalographic (EEG) and the spatial resolution of functional magnetic resonance imaging (fMRI). Data from 20 participants were acquired in different sessions per method. We expected the conflict-related N200 event-related potential (ERP) component and areas associated with flanker processing to show validity-specific modulations. Additionally, the spatio-temporal dynamics during cued flanker processing were examined using an fMRI-constrained source analysis approach.In the ERP data we found early differences in flanker processing between validity levels. An early centro-parietal relative positivity for incongruent stimuli occurred only with valid cueing during the N200 time window, while a subsequent fronto-central negativity was specific to invalidly cued interference processing. The source analysis additionally pointed to separate neural generators of these effects. Regional sources in visual areas were involved in conflict processing with valid cueing, while a regional source in the anterior cingulate cortex (ACC) seemed to contribute to the ERP differences with invalid cueing. Moreover, the ACC and precentral gyrus demonstrated an early and a late phase of congruency-related activity differences with invalid cueing. We discuss the first effect to reflect conflict detection and response activation while the latter more likely originated from conflict monitoring and control processes during response competition.