Distinct roles of forward and backward alpha-band waves in spatial visual attention
Previous research has associated alpha-band [8-12Hz] oscillations with inhibitory functions: for instance, several studies showed that visual attention increases alpha-band power in the hemisphere ipsilateral to the attended location. However, other studies demonstrated that alpha oscillations positively correlate with visual perception, hinting at different processes underlying their dynamics. Here, using an approach based on traveling waves, we demonstrate that there are two functionally distinct alpha-band oscillations propagating in different directions. We analyzed EEG recordings from three datasets of human participants performing a covert visual attention task (one new dataset with N=16, two previously published datasets with N=16 and N=31). Participants were instructed to detect a brief target by covertly attending to the screen's left or right side. Our analysis reveals two distinct processes: allocating attention to one hemifield increases top-down alpha-band waves propagating from frontal to occipital regions ipsilateral to the attended location, both with or without visual stimulation. These top-down oscillatory waves correlate positively with alpha-band power in frontal and occipital regions. Yet, different alpha-band waves propagate from occipital to frontal regions and contralateral to the attended location. Crucially, these forward waves were present only during visual stimulation, suggesting a separate mechanism related to visual processing. Together, these results reveal two distinct processes reflected by different propagation directions, demonstrating the importance of considering oscillations as traveling waves when characterizing their functional role.
Three datasets have been analyzed in this study and all of them are available from the Open Science Framework (as specified in the 'Methods/Participants' section). Code to analyze the data is available here: https://github.com/artipago/Travelling-waves-EEG-2.0, as specified in the 'Methods/Statistical analysis' section
Distinct roles of forward and backward alpha-band waves in spatial visual attentionOSF, DOI: https://osf.io/PN784/.
Alpha-Band Oscillations Enable Spatially and Temporally Resolved Tracking of Covert Spatial AttentionOSF, https://doi.org/10.17605/OSF.IO/M64UE.
Neural Evidence for the Contribution of Active Suppression During Working Memory FilteringOSF, https://doi.org/10.1093/cercor/bhx336.
Article and author information
European Research Council (101075930)
- Andrea Alamia
Agence Nationale de la Recherche (ANR-19-PI3A-0004)
- Rufin VanRullen
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Human subjects: This study adheres to the guidelines for research at the "Centre de Recherche Cerveau et Cognition," and the protocol was approved by the local ethical committee "Commité de protection des Personnes Sud Méditerranée 1" (ethics approval number N˚ 2019-A02641-56).
- Jonas Obleser, University of Lübeck, Germany
- Preprint posted: August 18, 2022 (view preprint)
- Received: November 18, 2022
- Accepted: March 5, 2023
- Accepted Manuscript published: March 6, 2023 (version 1)
© 2023, Alamia et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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