Siemann Julia, Herrmann Manfred, Galashan Daniela
Department of Neuropsychology and Behavioral Neurobiology, Center for Cognitive Sciences (ZKW), University of Bremen, Bremen, Germany; Center for Advanced Imaging (CAI), University of Bremen, Bremen, Germany.
Neuroimage. 2016 Aug 1;136:45-56. doi: 10.1016/j.neuroimage.2016.05.036. Epub 2016 May 13.
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.
通常，不一致的侧翼刺激会引发冲突处理，而一致的侧翼刺激则应促进任务表现。各种行为研究报告称，正确定向的选择性注意可改善冲突处理，甚至消除冲突处理。在本研究中，我们试图重新研究这些行为效应，并利用脑电图（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方法，梳理出注意力提示效应背后的神经元活动模式。每种方法在不同的时间段采集了20名参与者的数据。我们预期与冲突相关的N200事件相关电位（ERP）成分以及与侧翼处理相关的区域会表现出有效性特异性调制。此外，使用fMRI约束源分析方法检查了提示侧翼处理期间的时空动态。在ERP数据中，我们发现有效性水平之间侧翼处理的早期差异。仅在N200时间窗口内有效提示时，不一致刺激才会出现早期中央顶叶相对正电位，而随后的额中央负电位则特定于无效提示的干扰处理。源分析还指出了这些效应的不同神经发生器。视觉区域的区域源参与有效提示的冲突处理，而前扣带回皮质（ACC）的区域源似乎导致无效提示时的ERP差异。此外，ACC和中央前回在无效提示时表现出与一致性相关的活动差异的早期和晚期阶段。我们讨论第一种效应反映冲突检测和反应激活，而后者更可能源于反应竞争期间的冲突监测和控制过程。
