Selection and updating of mental representations in working memory: A combined MEG and fMRI approach

工作记忆（WM）使我们能够维持和操纵不同种类的信息来指导未来的行为。它包括两个组件：短期存储和对存储内容进行操作的执行进程。从记忆中活跃的信息中选择相关信息片段和更新当前关注的信息片段的过程通常被认为是WM的核心执行过程。尽管先前的研究已经阐明了短期存储的机制及其与执行过程的分离性，无论是单细胞记录还是使用功能磁共振成像和MEG/EEG的神经成像方法，但在WM中支持不同执行操作的神经网络仍然难以捉摸。本研究采用功能磁共振成像和脑磁图的双因子联合研究，以健康受试者为研究对象，研究WM的两个子过程，即WM项目的选择和当前关注的WM项目的更新。除了简单的主效应外，建议的析因设计将提供关于两个假定的子过程是否在神经水平上相互作用的证据。通过功能磁共振成像和脑磁图分别获得的空间和时间信息的整合，将允许在时间和空间上对影响进行定位，并跟踪信号的时空演变。此外，通过fmri约束下的MEG分析识别源激活的时间过程应使用，以探测分布的大脑区域之间的动态耦合，表征其通信的时代性和方向性。

Working memory (WM) enables us to maintain and manipulate different kinds of information to guide future behaviour. It includes two components: short-term storage and executive processes that operate on the stored contents. The process of selecting relevant pieces of information amongst those held active in memory and the updating of the currently focused items are commonly considered as core executive processes of WM. Whereas prior studies have elucidated the mechanisms of shortterm storage and its dissociability from executive processes, both in single-cell recordings and in neuroimaging approaches using fMRI and MEG/EEG, the neural networks supporting different executive operations within WM have remained elusive. Here, two of these sub-processes of WM, selection amongst WM items and updating of the currently focused WM item, shall be investigated in a two-factorial combined fMRI and MEG study with healthy subjects. In surplus to the simple main effects, the proposed factorial design will yield evidence as to whether the two putative sub-processes interact at the neural level. Integration of spatial and temporal information obtained with fMRI and MEG, respectively, will allow for a localization of effects in both time and space and for tracking the signals' spatiotemporal evolution. In addition, the time courses of the source activations identified by fMRI-constrained MEG analysis shall be used to probe the dynamic coupling between distributed brain regions, characterising the timing and directedness of their communication.