Deciphering Neural Choreography: Theta and High-Alpha Phase-Locking Dynamics Unveil Face Perception in Ambiguous Stimuli

Poster Session F - Tuesday, April 16, 2024, 8:00 – 10:00 am EDT, Sheraton Hall ABC

Nan Liu¹, Ralph Weidner¹, Qi Chen², Gereon Fink^1,4, Silvia Daun^1,3; ¹Forschungszentrum Jülich, Jülich, Germany, ²South China Normal University, Guangzhou, China, ³University of Cologne, Cologne, Germany, ⁴University Hospital Cologne, University of Cologne, Cologne, Germany

Previous studies have established phase synchronization as a fundamental mechanism for integrating local features into coherent perceptions. In this study, we employed a novel paradigm and dynamic graph analysis based on electroencephalography (EEG) to track neural dynamics associated with perceiving a face or not while keeping the stimuli identical. Thirty participants underwent a pretest to establish perceptual thresholds for detecting faces within images overlaid with visual noise. These thresholds were then applied in an EEG experiment with the same task, focusing on images with 50% and 75% detection probabilities. In the high-alpha band, we observed increased coupling (110-325 ms post-stimulus) between left occipito‐temporal and right parieto-occipital regions when an ambiguous stimulus was perceived as a face, indicating conscious face perception. Subsequently, the failure to perceive a face results in enhanced theta band phase synchronization between left and right occipito-temporal face-selective areas, along with increased high-alpha band coupling between left prefrontal and right occipito-temporal regions. The theta synchronization, which occurs earlier, may be linked to the ongoing assembly of individual pieces of facial information, while the later increased high-alpha coupling suggests potential top-down modulation on visuospatial attention for gathering more information. Additionally, we identified left lateralized prefrontal-occipital couplings in the theta band related to the informational content of the stimulus, irrespective of whether the inherent face was perceived or not. These findings reveal distinct temporal dynamics in phase synchronization at specific frequencies, indicating a specialized system for face perception during integrated information processing across the frontal and visual cortex, resolving ambiguities.

Topic Area: PERCEPTION & ACTION: Vision