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 unified percepts.
• Understanding neural dynamics of conscious perception, especially face recognition, 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 neural activity when an ambiguous visual stimulus is perceived as a face versus not perceived.
• To explore the role of phase synchronization in integrating facial information across brain regions.

Main Methods:

• Utilized a novel paradigm with ambiguous visual stimuli and EEG recordings.
• Employed dynamic graph analysis to track neural phase synchronization.
• Established individual perceptual thresholds for face detection in noisy images.
• Analyzed brain activity at 50% and 75% detection probabilities.

Main Results:

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

Conclusions:

• Distinct temporal dynamics in phase synchronization at specific frequencies characterize face perception.
• Evidence suggests a specialized neural system for face perception involving integrated information processing across frontal and visual cortices.
• Observed synchronizations likely reflect continuous information gathering rather than a simple binary perception signal.