Brain mechanisms underlying the brief maintenance of seen and unseen sensory information

I am glad to say that my work with Jean-Remi King and Stan Dehaene has been recently accepted for publication in the prestigious journal Neuron. You can find a preliminary version here.

Recent studies of “unconscious working memory” challenge the notion that only visible stimuli can be actively maintained over time. In the present study, we investigated the neural dynamics underlying the brief maintenance of subjectively invisible stimuli, using machine learning and magnetoencephalography. Subjects were presented with a masked Gabor patch whose angle had to be briefly memorized. We show that the stimulus is  encoded in early brain activity independently of its visibility, and that the maintenance of its presence and orientation can be decoded throughout the retention period, even in the invisible condition. Source and temporal generalization analyses revealed that perceptual maintenance depends on a deep hierarchical network ranging from early visual cortex to temporal, parietal and frontal cortices. Importantly, the representations coded in the late processing stages of this network specifically predict subjective reports. These results challenge several predictions of consciousness theories and suggest that unseen information can be briefly maintained within the higher processing stages of visual perception.

Highlights:

  • The link between working memory and visual awareness has recently been challenged
  • We here study the mechanism of unconscious maintenance with MEG & machine learning
  • Unseen stimuli can be partially and maintained within high cortical assemblies
  • We show how to revise awareness theories to account for the maintenance of unseen stimuli