Alpha and gamma oscillations characterize feedback and feedforward processing in monkey visual cortex

Timo van Kerkoerle, Matthew W. Self, Bruno Dagnino, Marie-Alice Gariel-Mathis, Jasper Poort, Chris van der Togt, Pieter R. Roelfsema
2014 Proceedings of the National Academy of Sciences of the United States of America  
This Feature Article is part of a series identified by the Editorial Board as reporting findings of exceptional significance. Edited by Terrence J. Sejnowski, Cognitive functions rely on the coordinated activity of neurons in many brain regions, but the interactions between cortical areas are not yet well understood. Here we investigated whether lowfrequency (α) and high-frequency (γ) oscillations characterize different directions of information flow in monkey visual cortex. We recorded from
more » ... layers of the primary visual cortex (V1) and found that γ-waves are initiated in input layer 4 and propagate to the deep and superficial layers of cortex, whereas α-waves propagate in the opposite direction. Simultaneous recordings from V1 and downstream area V4 confirmed that γand α-waves propagate in the feedforward and feedback direction, respectively. Microstimulation in V1 elicited γ-oscillations in V4, whereas microstimulation in V4 elicited α-oscillations in V1, thus providing causal evidence for the opposite propagation of these rhythms. Furthermore, blocking NMDA receptors, thought to be involved in feedback processing, suppressed α while boosting γ. These results provide new insights into the relation between brain rhythms and cognition. neuronal synchronization | attention | perceptual organization | phase coherence | Granger causality
doi:10.1073/pnas.1402773111 pmid:25205811 pmcid:PMC4210002 fatcat:3gpps3wtsfc2zc5r5tfrs647a4