Dynamic brain causal connectivity of audiovisual integration under endogenous attention regulation

Abstract

The dorsolateral frontoparietal network (frontal eye field (FEF) and inferior parietal lobule (IPL)) has been proven related to endogenous attention, while the superior temporal gyrus (STG) has been proven related to audiovisual integration. However, the dynamic causal mechanism of these three brain regions in the process of audiovisual integration under endogenous attention regulation is still unclear. To explore the dynamic brain connection of audiovisual integration under endogenous attention regulation, functional magnetic resonance imaging(fMRI) data were collected from 49 young normal participants (mean age 23 years) when accomplishing three tasks of only audio (A), only visual (V), and audiovisual attention (VA) task under the endogenous attention. 15 models were established utilizing dynamic causal modelling and the optimal model was obtained by the Bayesian model selection. The difference in effective connectivity of the optimal model under different tasks was compared to both hemispheres respectively. We found the optimal models of three tasks in both hemispheres were all STG-oriented driving-inputs, and the modulations were fully-connected models. The paired t-test showed there were significant differences in IPL→FEF, and STG→FEF between the VA and A task in the left hemisphere, and IPL→FEF, STG→FEF, FEF→STG between the VA and V task in the right. It concluded that the audiovisual integration process under the endogenous attention regulation depends on the collaboration of the frontoparietal network and the superior temporal gyrus. The enhanced connection within frontoparietal networks would play a role in distributing attention to different modalities, and the superior temporal gyrus deals with specific stimuli contents.