Theta and High-alpha Phase-locking Dynamics Unveil Face Perception in Ambiguous Stimuli

Area of Science:

• Neuroscience
• Cognitive Science
• Perception Research

Background:

• Phase synchronization is crucial for integrating sensory information into coherent perceptions.
• Understanding the neural dynamics of face perception, especially with ambiguous stimuli, remains a key challenge.

Purpose of the Study:

• To investigate the neural dynamics of conscious face perception using electroencephalography (EEG) and dynamic graph analysis.
• To differentiate brain activity when an ambiguous stimulus is perceived as a face versus not perceived.

Main Methods:

• Utilized a novel EEG paradigm with dynamic graph analysis to track neural activity.
• Participants performed a face detection task with visual noise at varying detection probabilities (50% and 75%).
• Analyzed phase synchronization in specific frequency bands (theta and high-alpha) between different brain regions.

Main Results:

• Increased high-alpha band coupling between occipitotemporal electrodes correlated with perceiving a face (100-275 ms post-stimulus).
• Failure to perceive a face showed enhanced theta band synchronization and specific high-alpha band coupling involving frontal electrodes.
• Frontal-occipitotemporal theta-band couplings reflected stimulus information content regardless of perception.

Conclusions:

• Distinct temporal dynamics in phase synchronization at specific frequencies underpin specialized face perception.
• Neural synchrony likely reflects continuous information gathering rather than a simple face/no-face binary signal.
• Findings suggest integrated information processing across frontal and visual cortices resolves perceptual ambiguities in face detection.