Working memory load improves early stages of independent visual processing

Increasing evidence suggests that working memory and perceptual processes are dynamically interrelated due to modulating activity in overlapping brain networks. However, the direct influence of working memory on the spatio-temporal brain dynamics of behaviorally relevant intervening information remains unclear. To investigate this issue, subjects performed a visual proximity grid perception task under three different visual–spatial working memory (VSWM) load conditions. VSWM load was manipulated by asking subjects to memorize the spatial locations of 6 or 3 disks. The grid was always presented between the encoding and recognition of the disk pattern. As a baseline condition, grid stimuli were presented without a VSWM context. VSWM load altered both perceptual performance and neural networks active during intervening grid encoding. Participants performed faster and more accurately on a challenging perceptual task under high VSWM load as compared to the low load and the baseline condition. Visual evoked potential (VEP) analyses identified changes in the configuration of the underlying sources in one particular period occurring 160–190 ms post-stimulus onset. Source analyses further showed an occipito-parietal down-regulation concurrent to the increased involvement of temporal and frontal resources in the high VSWM context. Together, these data suggest that cognitive control mechanisms supporting working memory may selectively enhance concurrent visual processing related to an independent goal. More broadly, our findings are in line with theoretical models implicating the engagement of frontal regions in synchronizing and optimizing mnemonic and perceptual resources towards multiple goals.

Research highlights▶ The influence of working memory on the spatio-temporal brain dynamics associated with processing independent, but behaviorally relevant, sensory information is unexplored. ▶ Visual working memory load appears to facilitate perceptual processes in situations where the visual input is behaviorally relevant but not related to the information concurrently maintained in working memory. ▶ EEG analyses showed that the processing of the perceptual stimulus under high working memory load is related to a concurrent reduction of occipito-parietal brain activity and enhancement of fronto-temporal activity between 160 and 190 ms post stimulus onset. ▶ Together our data suggest that cognitive control mechanisms supporting visual working memory may selectively enhance visual perceptual processes of behaviorally relevant sensory input.