Hemispheric Asymmetry of Feedback-Driven Synergistic Information Processing During Face Perception

The human brain excels at integrating complex sensory information to support coherent perception and behavior. However, the mechanisms through which distributed neural signals interact across time, space, and hierarchical levels remain incompletely understood. Here, we applied partial information decomposition (PID) to magnetoencephalography (MEG) data to quantify synergistic information—a form of higher-order, non-additive integration—during the processing of normal and two-tone (Mooney) faces. We observed two temporally distinct synergy peaks corresponding to the initial stimulus processing and later memory-based task stages. Notably, Mooney faces elicited delayed and amplified information synergy, especially in the right occipitotemporal cortex, reflecting feedback-dominant processing under ambiguity. Spatial correlation analyses revealed hemispheric asymmetries: the left hemisphere exhibited distributed and additive synergy patterns, while the right hemisphere showed nonlinear, emergent integration from fewer sources. At the network level, synergistic information flow was rerouted toward right-lateralized hubs, particularly under ambiguity. Moreover, feedback processing exhibited enhanced synergy information, highlighting the computational role of top-down signals. Finally, the synergy information during early perception can predict synergy information when the stimulus disappears in the right OFA, suggesting its important role in temporal integration. Together, these findings demonstrate that synergy information captures dynamic, directional, and sustained computations in the human brain. By validating and extending known neurocognitive principles, our approach exemplifies how advanced information-theoretic approach can reveal the underlying computational architecture of perceptual inference.