Differential brain mechanisms of selection and maintenance of information during working memory

Working memory is our ability to select and temporarily hold information as needed for complex cognitive operations. The temporal dynamics of sustained and transient neural activity supporting the selection and holding of memory content is not known. To address this problem, we recorded magnetoencephalography (MEG) in healthy participants performing a retro-cue working memory task in which the selection rule and the memory content varied independently. Multivariate decoding and source analyses showed that selecting the memory content relies on prefrontal and parieto-occipital persistent oscillatory neural activity. By contrast, the memory content was reactivated in a distributed occipito-temporal posterior network, preceding the working memory decision and in a different format that during the visual encoding. These results identify a neural signature of content selection and characterize differentiated spatiotemporal constraints for subprocesses of working memory. SIGNIFICANCE STATEMENT Our brain selects and maintains information during short time windows in a way that is essential to reasoning and learning. Recent advances in multivariate analysis of brain activity allowed the characterization of brain regions that stores the memory content, but the spatiotemporal neural dynamics underlying working memory sub-processes, namely encoding, selection and maintenance, are not known. We applied multivariate analysis to time-resolved brain signal to characterize the spatiotemporal signature underlying these sub-processes. Selection of information relies on sustained oscillatory activity in a network that includes the ventrolateral prefrontal cortex while memory content is transiently replayed in an occipito-temporal network that differs from encoding. Our results characterized differentiated spatiotemporal activity underlying encoding, selection and maintenance of information during working memory.