Working memory processing of natural environmental scenes in the human brain revealed by MEG

Abstract Results of the previous studies on working memory processing of natural scenes in the human brain using fMRI have shown activation of a distributed network involving mainly medial temporal lobe and prefrontal sources. In spite of its relative high spatial accuracy in localizing the involved areas, possible interactions between the localized source activities in time are played in a finer temporal scale. In this study we used multichannel whole-head magnetoencephalography (MEG) which possesses both a relative good spatial and temporal resolution, to shed light on the possible mechanisms of interactions between the involved sources in the brain, after localizing them properly. 12 healthy human subjects were presented with a small set of natural scenes from the seaside. The memory task was a continuous 1-back comparison task, and the control was an automatic visuomotor response task involving the same sequence of trials (the order of task performance was random). For source estimation a weighted L2 minimum-norm algorithm was used. Focusing in a time interval between 300–600 ms when the impact of deep encoding of the presented stimuli during the 1-back task performance is more prominent and comparable, the interaction between the localized occipital, inferior medial temporal, posterior parietal, and prefrontal sources, was found to be important for deep (elaborative) encoding of these stimuli in working memory.