Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, The Netherlands.
Neuroimage. 2012 Jan 2;59(1):682-94. doi: 10.1016/j.neuroimage.2011.07.018. Epub 2011 Jul 19.
This study was designed to investigate the spatio-temporal characteristic of face selection in the context of the Biased Competition (BC) model using electroencephalography (EEG). Pairs of similar (SIM) or dissimilar (DISS) faces were presented simultaneously. Subjects had to attend to one face (ATT) or ignore both faces (IGN). According to the BC account, simultaneously presented faces compete for representation. Spatial attention biases these competitive interactions towards neural processing of the attended face alone. A preceding functional magnetic resonance imaging (fMRI) study confirmed the validity of BC as selection principle in the occipital face area (OFA) and in the fusiform face area (FFA) (IGN SIM<IGN DISS; ATT SIM=ATT DISS) (Gentile and Jansma, 2010). The directionality of the similarity modulation within the IGN condition was interpreted in line with the assumption that within FFA similar faces are more likely to be encoded by largely overlapping population of neurons, hence leading to a stronger competition. In the present EEG experiment we investigated when neural competition and the bias effect take place. Using independent component analysis (ICA), we focused on face-processing-related components N170 and N250. Whereas we could not find any context-dependent modulation of the N170, we observed a context x task interaction within the N250 time-window. Together, the fMRI and EEG results suggested that faces competed for representation (IGN SIM<IGN DISS) in the N250 time-window within FFA. In addition, at the same latency (250 ms post-stimulus onset) and region of interest (FFA) the data supported the idea that attention solved neural competition in favor of the relevant face (ATT SIM=ATT DISS). We also observed a main effect of attention frontally within the N2b time-window, i.e. about 50 ms later than the attentional bias that solved competitive interactions. Based on these findings, it is plausible to conclude that this frontal activity was not directly involved in the bias control during selection in FFA.
本研究旨在使用脑电图（EEG）研究在有偏向竞争（BC）模型背景下对面部选择的时空特征。同时呈现相似（SIM）或不同（DISS）的面孔。要求被试注视一张面孔（ATT）或忽略两张面孔（IGN）。根据 BC 理论，同时呈现的面孔会竞争代表权。空间注意力会将这些竞争相互作用偏向于仅对被注视面孔的神经处理。之前的一项功能磁共振成像（fMRI）研究证实了 BC 作为选择原理在枕部面孔区（OFA）和梭状回面孔区（FFA）中的有效性（IGN SIM<IGN DISS；ATT SIM=ATT DISS）（Gentile 和 Jansma，2010）。在 IGN 条件下相似性调制的方向性与假设一致，即在 FFA 中，相似的面孔更有可能由神经元的重叠部分进行编码，因此导致更强的竞争。在本 EEG 实验中，我们研究了神经竞争和偏向效应何时发生。我们使用独立成分分析（ICA），重点关注与面孔处理相关的 N170 和 N250 成分。虽然我们没有发现 N170 存在任何与上下文相关的调制，但我们在 N250 时间窗口内观察到了上下文与任务的交互作用。总的来说，fMRI 和 EEG 结果表明，在 FFA 中的 N250 时间窗口内，面孔为代表权而竞争（IGN SIM<IGN DISS）。此外，在相同的潜伏期（刺激后 250 毫秒）和感兴趣区域（FFA）中，数据支持了注意力解决神经竞争以有利于相关面孔（ATT SIM=ATT DISS）的想法。我们还在 N2b 时间窗口内观察到了注意力的主要额叶效应，即在解决竞争相互作用的注意力偏向之后约 50 毫秒。基于这些发现，可以合理地得出结论，认为这种额叶活动并未直接参与 FFA 中选择过程中的偏向控制。
