Ecole des Neurosciences de Paris Ile-de-France, 15 rue de l'Ecole de médecine, Paris, France; Université Pierre et Marie Curie, 4 Place Jussieu, Paris, France; Cognitive Neuroimaging Unit, CEA DSV/I2BM, INSERM, Université Paris-Sud, Université Paris-Saclay, NeuroSpin center, Gif/Yvette, France
Sébastien Marti
Cognitive Neuroimaging Unit, CEA DSV/I2BM, INSERM, Université Paris-Sud, Université Paris-Saclay, NeuroSpin center, Gif/Yvette, France
Andrés Ojeda
Department of Zoology, University of Oxford, Oxford, United Kingdom
Jean-Rémi King
Department of Psychology, New York University, New York, United States; Frankfurt Institute for Advanced Studies, Frankfurt, Germany
Yuanyuan Mi
Brain Science Center, Institute of Basic Medical Sciences, Beijing, China
Misha Tsodyks
Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel; Department of Neuroscience, Columbia University, New York, United States
Stanislas Dehaene
Cognitive Neuroimaging Unit, CEA DSV/I2BM, INSERM, Université Paris-Sud, Université Paris-Saclay, NeuroSpin center, Gif/Yvette, France; Collège de France, 11 Place Marcelin Berthelot, Paris, France
Working memory and conscious perception are thought to share similar brain mechanisms, yet recent reports of non-conscious working memory challenge this view. Combining visual masking with magnetoencephalography, we investigate the reality of non-conscious working memory and dissect its neural mechanisms. In a spatial delayed-response task, participants reported the location of a subjectively unseen target above chance-level after several seconds. Conscious perception and conscious working memory were characterized by similar signatures: a sustained desynchronization in the alpha/beta band over frontal cortex, and a decodable representation of target location in posterior sensors. During non-conscious working memory, such activity vanished. Our findings contradict models that identify working memory with sustained neural firing, but are compatible with recent proposals of ‘activity-silent’ working memory. We present a theoretical framework and simulations showing how slowly decaying synaptic changes allow cell assemblies to go dormant during the delay, yet be retrieved above chance-level after several seconds.