Working memory and conscious perception are often thought to rely on the same brain mechanisms, but recent evidence suggests non-conscious working memory exists. Using visual masking and magnetoencephalography in a spatial delayed-response task, participants reported the location of a subjectively unseen target above chance after a long delay. Conscious perception and conscious working memory showed sustained alpha/beta desynchronization over frontal cortex and decodable target location in posterior sensors. During non-conscious working memory, these signals vanished, contradicting models equating working memory with sustained neural firing. The findings support 'activity-silent' working memory, where slowly decaying synaptic changes allow cell assemblies to go dormant during the delay yet be retrieved above chance after seconds.
Conscious perception of a stimulus is linked to a specific sequence of brain processes that unfold after about 270 milliseconds, involving superior parietal and superior frontal regions. Using EEG and MEG recordings during a task where participants reported the location and visibility of a brief visual target, multivariate pattern analysis showed that information about stimulus location is still processed in the cortex even when the stimulus is not consciously seen (blindsight). However, only consciously perceived stimuli trigger additional, time-limited neural activity in higher-order brain areas, whereas unconscious processing decays slowly without this chain of activity.