Timo van Kerkoerle

28 septembre 2016

Unité INSERM-CEA 562 "Neuroimagerie Cognitive, NeuroSpin, Gif-sur-Yvette

Cortical mechanisms of attention and working memory

invité par Guillaume Masson

Abstract :

Our perception is an inherently active process. We dynamically select information that is behaviorally relevant for us at given moments in time, enabling us to interact effectively with the world around us. This ability is thought to depend on cortical feedback from higher cortical areas to early sensory areas, but this process remains poorly understood. Here we investigated the cortical mechanisms of attention and working memory in monkey visual cortex. We used laminar recordings to distinguish feedforward from feedback processing. We found that feedback input to V1 was equally strong during visual attention and working memory, but that the effects in terms of spiking activity depended on the presence of a visual stimulus. Furthermore, we tested whether rhythmic activity can also differentiate between the two streams of visual processing. Using both correlational and causal techniques we demonstrated that gamma oscillations characterize feedforward processing while the alpha rhythm signatures feedback processing. This suggest a dual role of feedback to early visual areas, a sustained mode that enhances relevant information and an alpha synchronized mode that reflects the active suppression of distracting information.

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