Early Cortical Connective Network Relating to Audiovisual Stimulation by Partial Directed Coherence Analysis

Abstract

Cross-modal sensory integration between the auditory and visual systems has long been a topic of interest in cognitive neuroscience, but spatiotemporal cortical interdependence under audiovisual stimulation is still poorly understood. In this letter, parametric spectral analysis, specifically partial directed coherence (PDC), is used to study the cortical connective causal-interdependence network under audiovisual cognitive processes within the time window of the N1 component, i.e., 96--145 ms poststimulus in the event-related potential (ERP). A total of 13 subjects (age: 22.9+/-0.8 years; male/female = 9/4) performed an audiovisual recognition task. Multichannel EEG signals were analyzed using an adaptive multivariate autoregressive model to identify causal influences between different cortical areas. Three different cortical connective networks were detected, and by comparing the cortical PDC network in the early cognitive process of audiovisual (VA) perception with that in unimodal situations (V or A), it was found that the left temporal cortex (TC) might be responsible for audiovisual integration. Such electrophysiological findings were highly consistent with previous functional neuroimaging results. Moreover, the results presented here show the dynamics of lateral causal influences during audiovisual integration.