Zumer Johanna M, Scheeringa René, Schoffelen Jan-Mathijs, Norris David G, Jensen Ole
Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, Centre for Cognitive Neuroimaging, Nijmegen, The Netherlands.
Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, Centre for Cognitive Neuroimaging, Nijmegen, The Netherlands; Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands.
PLoS Biol. 2014 Oct 21;12(10):e1001965. doi: 10.1371/journal.pbio.1001965. eCollection 2014 Oct.
Given the limited processing capabilities of the sensory system, it is essential that attended information is gated to downstream areas, whereas unattended information is blocked. While it has been proposed that alpha band (8-13 Hz) activity serves to route information to downstream regions by inhibiting neuronal processing in task-irrelevant regions, this hypothesis remains untested. Here we investigate how neuronal oscillations detected by electroencephalography in visual areas during working memory encoding serve to gate information reflected in the simultaneously recorded blood-oxygenation-level-dependent (BOLD) signals recorded by functional magnetic resonance imaging in downstream ventral regions. We used a paradigm in which 16 participants were presented with faces and landscapes in the right and left hemifields; one hemifield was attended and the other unattended. We observed that decreased alpha power contralateral to the attended object predicted the BOLD signal representing the attended object in ventral object-selective regions. Furthermore, increased alpha power ipsilateral to the attended object predicted a decrease in the BOLD signal representing the unattended object. We also found that the BOLD signal in the dorsal attention network inversely correlated with visual alpha power. This is the first demonstration, to our knowledge, that oscillations in the alpha band are implicated in the gating of information from the visual cortex to the ventral stream, as reflected in the representationally specific BOLD signal. This link of sensory alpha to downstream activity provides a neurophysiological substrate for the mechanism of selective attention during stimulus processing, which not only boosts the attended information but also suppresses distraction. Although previous studies have shown a relation between the BOLD signal from the dorsal attention network and the alpha band at rest, we demonstrate such a relation during a visuospatial task, indicating that the dorsal attention network exercises top-down control of visual alpha activity.
鉴于感觉系统的处理能力有限，至关重要的是，被关注的信息被传递到下游区域，而未被关注的信息则被阻断。虽然有人提出，阿尔法波段（8 - 13赫兹）的活动通过抑制任务无关区域的神经元处理来将信息路由到下游区域，但这一假设仍未得到验证。在这里，我们研究了在工作记忆编码期间，通过脑电图在视觉区域检测到的神经元振荡如何用于控制在下游腹侧区域通过功能磁共振成像同时记录的血氧水平依赖（BOLD）信号所反映的信息。我们使用了一种范式，其中16名参与者在左右半视野中分别看到面孔和风景；一个半视野被关注，另一个未被关注。我们观察到，与被关注对象对侧的阿尔法功率降低预测了腹侧对象选择区域中代表被关注对象的BOLD信号。此外，与被关注对象同侧的阿尔法功率增加预测了代表未被关注对象的BOLD信号的降低。我们还发现，背侧注意网络中的BOLD信号与视觉阿尔法功率呈负相关。据我们所知，这是首次证明阿尔法波段的振荡与从视觉皮层到腹侧流的信息控制有关，这在具有代表性的特定BOLD信号中得到了体现。感觉阿尔法与下游活动之间的这种联系为刺激处理过程中的选择性注意机制提供了神经生理基础，这不仅增强了被关注的信息，还抑制了干扰。尽管先前的研究已经表明背侧注意网络的BOLD信号与静息状态下的阿尔法波段之间存在关系，但我们在视觉空间任务中证明了这种关系，表明背侧注意网络对视觉阿尔法活动进行自上而下的控制。
