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

工作记忆(WM)使我们能够保持和操纵不同类型的信息，以指导未来的行为。它包括两个组成部分：短期存储和对存储内容进行操作的执行过程。从记忆中活跃的信息中选择相关信息的过程和更新当前集中的项目通常被认为是工作管理的核心执行过程。虽然先前的研究已经阐明了短期储存的机制及其与执行过程的分离，无论是在单细胞记录中，还是在使用fMRI和MEG/EEG的神经成像方法中，支持WM内不同执行操作的神经网络仍然难以捉摸。这里，WM的两个子过程--选择WM项目和更新当前关注的WM项目--应该在健康受试者的双因素fMRI和MEG联合研究中进行调查。除了简单的主效应外，建议的析因设计将提供证据，证明这两个假定的子过程是否在神经水平上相互作用。将fMRI和MEG分别获得的空间和时间信息相结合，将允许在时间和空间上定位效应并跟踪信号的时空演变。此外，fMRI受限脑磁图分析确定的源激活的时间进程应用于探索分布的脑区之间的动态耦合，以表征它们通信的时序性和方向性。

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.