Camille Fakche¹ (), Laurie Galas¹, Kirtsen Petras¹, Laura Dugué^1,2; ¹Université Paris Cité, CNRS, Integrative Neuroscience and Cognition Center, F-75006 Paris, France, ²Institut Universitaire de France (IUF), F-75005 Paris, France

Voluntary, spatial attention has been associated with alpha brain oscillations (8-12Hz) resulting in periodic behavioral performance. It was recently proposed that considering the spatial dimension of brain oscillations could explain more of the variance in performance (Fakche and Dugué, 2023). Here, we tested the hypothesis that attentional allocation is related to alpha traveling waves (Alamia et al., 2023), i.e., the propagation of alpha oscillations with a monotonic phase shift across cortical locations. Healthy human participants (n=20) performed a detection task while their brain activity was recorded with electroencephalography (EEG). Attention was first manipulated using a cue instructing participants to direct their spatial attention to either the bottom right or left quadrant. After a 1500ms-delay, a checkerboard stimulus flickering at 10Hz (visual inducer) was presented for 4500ms. During this presentation, a low contrast target was flashed at the attended (valid) or unattended (invalid) location, and participants were instructed to press a key when detecting it. Behavioral responses showed higher detection performance for valid than invalid trials, and EEG responses in the cue-to-stimulus period showed alpha lateralization (higher alpha amplitude in the ipsilateral electrodes relative to the cued location). These control analyses confirmed that voluntary attention was successfully manipulated. Alpha traveling waves were then assessed using optical flow analysis, i.e., a technique for tracking the displacement of similarly valued pixels over a sequence of sensor array snapshots, to reveal spatio-temporal patterns of phase variations in the data. Our results showed that although the 10Hz-visual inducer produced posterior-to-anterior propagation of 10Hz oscillations, attentional orienting (cue-to-stimulus period) showed alternating anterior-to-posterior and posterior-to-anterior alpha traveling waves. We speculate that the alternation of top-down and bottom-up traveling waves reflects functional communication between sensory and higher-level brain areas.

Acknowledgements: This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No 852139 – Laura Dugué).