Zeng Yifan, Sauseng Paul, Alamia Andrea
Department of Psychology, Universität Zürich, Zürich 8050, Switzerland
Department of Psychology, Universität Zürich, Zürich 8050, Switzerland.
J Neurosci. 2024 Dec 11;44(50):e0532242024. doi: 10.1523/JNEUROSCI.0532-24.2024.
While previous works established the inhibitory role of alpha oscillations during working memory maintenance, it remains an open question whether such an inhibitory control is a top-down process. Here, we attempted to disentangle this issue by considering the spatiotemporal component of waves in the alpha band, i.e., alpha traveling waves. We reanalyzed two pre-existing and open-access EEG datasets ( = 180, 90 males, 80 females, 10 unknown) where participants performed lateralized, visual delayed match-to-sample working memory tasks. In the first dataset, the distractor load was manipulated (2, 4, or 6), whereas in the second dataset, the memory span varied between 1, 3, and 6 items. We focused on the propagation of alpha waves on the anterior-posterior axis during the retention period. Our results reveal an increase in alpha-band forward waves as the distractor load increased, but also an increase in forward waves and a decrease in backward waves as the memory set size increased. Our results also showed a lateralization effect: alpha forward waves exhibited a more pronounced increase in the hemisphere contralateral to the distractors, whereas the reduction in backward waves was stronger in the hemisphere contralateral to the targets. In short, the forward waves were regulated by distractors, whereas targets inversely modulated backward waves. Such a dissociation of goal-related and goal-irrelevant physiological signals suggests the coexistence of bottom-up and top-down inhibitory processes: alpha forward waves might convey a gating effect driven by distractor load, while backward waves may represent direct top-down gain control of downstream visual areas.
虽然先前的研究确定了α振荡在工作记忆维持过程中的抑制作用，但这种抑制控制是否是一个自上而下的过程仍然是一个悬而未决的问题。在这里，我们试图通过考虑α波段波的时空成分，即α行波，来解开这个问题。我们重新分析了两个现有的公开脑电图数据集（n = 180，男性90名，女性80名，10名未知），参与者在其中执行了侧向化的视觉延迟匹配样本工作记忆任务。在第一个数据集中，干扰物负荷被操纵（2、4或6），而在第二个数据集中，记忆跨度在1、3和6个项目之间变化。我们关注的是在保持期内α波在前后轴上的传播。我们的结果显示，随着干扰物负荷的增加，α波段向前波增加，但随着记忆集大小的增加，向前波也增加，向后波减少。我们的结果还显示了一种侧向化效应：α向前波在与干扰物对侧的半球中表现出更明显的增加，而向后波的减少在与目标对侧的半球中更强。简而言之，向前波受干扰物调节，而目标则反向调节向后波。这种与目标相关和与目标无关的生理信号的分离表明自下而上和自上而下的抑制过程共存：α向前波可能传达由干扰物负荷驱动的门控效应，而后向波可能代表对下游视觉区域的直接自上而下的增益控制。
