MEG Center, University of Tübingen, Tübingen, 72076, Germany; IMPRS-GTC, International Max-Planck Research School-Graduate Training Center for Neuroscience, Tübingen, 72074, Germany.
Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, 72076, Germany.
Neuroimage. 2020 Nov 15;222:117075. doi: 10.1016/j.neuroimage.2020.117075. Epub 2020 Jun 22.
Conscious perception of the emotional valence of faces has been proposed to involve top-down and bottom-up information processing. Yet, the underlying neuronal mechanisms of these two processes and the implementation of their cooperation is still unclear. According to the global workspace model, higher level cognitive processing of visual emotional stimuli relies on both bottom-up and top-down processing. Using masking stimuli in a visual backward masking paradigm with delays at the perceptual threshold, at which stimuli can only partly be detected, suggests that only top-down processing differs between correctly and incorrectly perceived stimuli, while bottom-up visual processing is not compromised and comparable for both conditions. Providing visual stimulation near the perceptual threshold in the backward masking paradigm thus enabled us to compare differences in top-down modulation of the visual information of correctly and incorrectly recognized facial emotions in 12 healthy individuals using magnetoencephalography (MEG). For correctly recognized facial emotions, we found a right-hemispheric fronto-parietal network oscillating in the high-beta and low-gamma band and exerting top-down control as determined by the causality measure of phase slope index (PSI). In contrast, incorrect recognition was associated with enhanced coupling in the gamma band between left frontal and right parietal regions. Our results indicate that the perception of emotional face stimuli relies on the right-hemispheric dominance of synchronized fronto-parietal gamma-band activity.
人们提出，对面部情绪效价的有意识感知涉及自上而下和自下而上的信息处理。然而，这两个过程的潜在神经机制及其合作的实施仍不清楚。根据全局工作空间模型，视觉情绪刺激的高级认知加工依赖于自上而下和自下而上的加工。在具有知觉阈限时延的视觉后向掩蔽范式中使用掩蔽刺激，在这种情况下，刺激只能部分被检测到，这表明只有自上而下的处理在正确和错误感知的刺激之间存在差异，而自下而上的视觉处理在两种情况下都没有受到影响且相当。因此，在向后掩蔽范式中在知觉阈限附近提供视觉刺激，使我们能够使用脑磁图 (MEG) 在 12 名健康个体中比较正确和错误识别面部情绪的视觉信息的自上而下调制的差异。对于正确识别的面部情绪，我们发现右侧额顶网络在高β和低γ频段振荡，并通过相位斜率指数 (PSI) 的因果度量确定执行自上而下的控制。相比之下，错误识别与左额区和右顶区之间的γ频段耦合增强有关。我们的研究结果表明，情绪面孔刺激的感知依赖于右侧额顶同步γ波段活动的优势。
