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

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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.