Jiang Yizhou, Xia Jing, Li Sijie, Chen Jiedan, Wang Pengfei, Chen Qi
Center for Studies of Psychological Application and School of Psychology, South China Normal University, China.
Department of Psychology and the Center for Mind and Brain, Guangzhou University, Guangzhou 510631, China.
Neuroscience. 2017 Jun 14;353:133-146. doi: 10.1016/j.neuroscience.2017.04.023. Epub 2017 Apr 24.
Even when performing invariant behavioral task repeatedly on invariant physical stimuli, our behavioral performance always changes as manifested in varying response times (RTs), which is associated with fluctuations in attentional control and thus the underlying self-organization states of the human brain. In a visuospatial task of the present fMRI study, physical stimuli differed across six levels of spatial scope, but were kept invariant within each level. The slower RTs with larger spatial area attended suggested higher demands on visuospatial attention. The slower RTs within each level, however, implicated worse attentional control since both the task and the physical stimuli were kept invariant within each level. The imaging results showed that slower RTs within each of the six levels were associated with higher but later activations in the frontoparietal network, and higher but later deactivations in the default-mode network (DMN). These findings thus for the first time suggested that the within-level variance of attentional control corresponded to dynamic changes in the frontoparietal network and the DMN, in terms of not only the height but also the latency of neural activity. Moreover, although the two networks are anti-correlated in terms of the height of neural activity, they are tightly coupled in terms of the temporal dynamics. Based on the current results, we proposed a tentative hypothesis on the optimal working mode of the frontoparietal attentional control system in the human brain: even a lower height of neural activity in frontoparietal network can significantly improve behavioral performance as long as it starts relatively early.
即使在对不变的物理刺激反复执行不变的行为任务时，我们的行为表现也总是会发生变化，表现为反应时间（RTs）的不同，这与注意力控制的波动相关，进而与人类大脑潜在的自组织状态相关。在本功能磁共振成像（fMRI）研究的视觉空间任务中，物理刺激在六个空间范围水平上有所不同，但在每个水平内保持不变。对较大空间区域的注视反应时间较慢，表明对视觉空间注意力的要求更高。然而，在每个水平内反应时间较慢，意味着注意力控制较差，因为在每个水平内任务和物理刺激都保持不变。成像结果表明，六个水平中每个水平内较慢 的反应时间与额顶叶网络中更高但更晚的激活以及默认模式网络（DMN）中更高但更晚的去激活相关。因此，这些发现首次表明，注意力控制的水平内差异不仅在神经活动的高度方面，而且在神经活动的潜伏期方面，都对应于额顶叶网络和DMN的动态变化。此外，尽管这两个网络在神经活动高度方面呈反相关，但在时间动态方面它们紧密耦合。基于当前结果，我们提出了一个关于人类大脑中额顶叶注意力控制系统最佳工作模式的初步假设：只要额顶叶网络中神经活动开始相对较早，即使其较低的神经活动高度也能显著提高行为表现。
