Changes of Effective Connectivity in the Alpha Band Characterize Differential Processing of Audiovisual Information in Cross-Modal Selective Attention

Cross-modal selective attention enhances the processing of sensory inputs that are most relevant to the task at hand.Such differential processing could be mediated by a swift network reconfiguration on the macroscopic level,but this remains a poorly understood process.To tackle this issue,we used a behavioral paradigm to introduce a shift of selective attention between the visual and auditory domains,and recorded scalp electroencephalographic signals from eight healthy participants.The changes in effective connectivity caused by the cross-modal attentional shift were delineated by analyzing spectral Granger Causality(GC),a metric of frequency-specific effective connectivity.Using data-driven methods of pattern-classification and feature-analysis,we found that a change in the a band(12 Hz-15 Hz) of GC is a stable feature across different individuals that can be used to decode the attentional shift.Specifically,auditory attention induces more pronounced information flow in the α band,especially from the parietal-occipital areas to the temporal-parietal areas,compared to the case of visual attention,reflecting a reconfiguration of interaction in the macroscopic brain network accompanying different processing.Our results support the role of α oscillation in organizing the information flow across spatially-separated brain areas and,thereby,mediating cross-modal selective attention.