eLife (Jul 2017)

A theory of working memory without consciousness or sustained activity

  • Darinka Trübutschek,
  • Sébastien Marti,
  • Andrés Ojeda,
  • Jean-Rémi King,
  • Yuanyuan Mi,
  • Misha Tsodyks,
  • Stanislas Dehaene

DOI
https://doi.org/10.7554/eLife.23871
Journal volume & issue
Vol. 6

Abstract

Read online

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.

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