title: Areas V1 and V2 show microsaccade-related 3-4-Hz covariation in gamma power and frequency.
abstract: Neuronal gamma-band synchronization (25-80 Hz) in visual cortex appears sustained and stable during prolonged visual stimulation when investigated with conventional averages across trials. However, recent studies in macaque visual cortex have used single-trial analyses to show that both power and frequency of gamma oscillations exhibit substantial moment-by-moment variation. This has raised the question of whether these apparently random variations might limit the functional role of gamma-band synchronization for neural processing. Here, we studied the moment-by-moment variation in gamma oscillation power and frequency, as well as inter-areal gamma synchronization, by simultaneously recording local field potentials in V1 and V2 of two macaque monkeys. We additionally analyzed electrocorticographic V1 data from a third monkey. Our analyses confirm that gamma-band synchronization is not stationary and sustained but undergoes moment-by-moment variations in power and frequency. However, those variations are neither random and nor a possible obstacle to neural communication. Instead, the gamma power and frequency variations are highly structured, shared between areas and shaped by a microsaccade-related 3-4-Hz theta rhythm. Our findings provide experimental support for the suggestion that cross-frequency coupling might structure and facilitate the information flow between brain regions.
authors.affiliation: Faculty of Psychology and Neuroscience, Maastricht University, PO Box 616, 6200, MD, Maastricht, The Netherlands.|Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands.
authors.forename: E
authors.initials: E
authors.lastname: Lowet
authors.affiliation: Faculty of Psychology and Neuroscience, Maastricht University, PO Box 616, 6200, MD, Maastricht, The Netherlands.|Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands.
authors.forename: M J
authors.initials: MJ
authors.lastname: Roberts
authors.affiliation: Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands.|Center for Neuroscience, Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: C A
authors.initials: CA
authors.lastname: Bosman
authors.affiliation: Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands.|Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, Frankfurt, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Fries
authors.affiliation: Faculty of Psychology and Neuroscience, Maastricht University, PO Box 616, 6200, MD, Maastricht, The Netherlands.|Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands.
authors.forename: P
authors.initials: P
authors.lastname: De Weerd
mesh_terms: D000818:Animals; D003344:Cortical Synchronization; D065818:Gamma Rhythm; D008253:Macaca mulatta; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D010775:Photic Stimulation; D012438:Saccades; D012815:Signal Processing, Computer-Assisted; D013826:Theta Rhythm; D014793:Visual Cortex / Q000502:physiology*
keywords: electrophysiology; gamma-band response; monkey; saccade; visual system