Yue Kong¹, Kirsten Petras¹, Philippe Marque^2,3, Rufin VanRullen^4,, Laura Dugué^1,5; ¹Université Paris Cité, CNRS, Integrative Neuroscience and Cognition Center, Paris, France, ²University Hospital of Toulouse, Toulouse, France, ³ToNIC (Toulouse NeuroImaging Center), Inserm, University of Toulouse 3, Toulouse, France, ⁴CerCo, CNRS, Universite de Toulouse, Toulouse, France, ⁵Institut Universitaire de France (IUF), Paris, France

Brain activity unfolds over both space and time, yet it is often approached from a single dimension with limited explanatory capacity. While the temporal properties of neural oscillations have been associated with visual attention, the potential functional relevance of their spatial propagation across the cortex –oscillatory Traveling Waves (oTW)– remains largely unexplored. A recent electroencephalography (EEG) study showed that alpha (8-12Hz) oTW propagate predominantly backward from frontal to occipital during sustained attentional orienting (Alamia et al., 2023; see also Fakche et al., VSS 2024). This raises the question about the functional role of oTW in inter-area communication, particularly during attentional exploration that requires interaction between frontal attentional regions and visual cortices (Fiebelkorn & Kastner, 2019; Kienitz et al., 2022). Here, we used Transcranial Magnetic Stimulation (TMS) to assess the causal link between attentional exploration, frontal eye field (FEF) activity and oTW. Human participants (N=16) performed a challenging visual search task, identifying the presence or absence of a target letter "T" among distractor "L"s (in left visual field), while their brain activity was recorded with EEG. At various delays after stimulus onset, a double-pulse of TMS (25 ms interval) was applied to the right FEF or to the vertex (control site). The behavioral results revealed a periodic pattern of FEF interference at ~6 Hz, i.e., TMS over the FEF (and not the vertex) modulated performance as a function of the stimulus-onset-to-pulse delay. We then characterized oTW properties (i.e., direction and speed) with optical flow analysis (Townsend & Gong, 2018; Gutzen et al., 2024), and observed that the patterns of oTW correlated with visual search performance. Together, our results contribute empirical evidence clarifying the causal role of oTW in inter-area neural communication during attentional exploration.

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) and was also supported by a doctoral fellowship from Université Paris Cité to Yue Kong.