The Study Of Visual Attentional Orienting Networks Based On The Dynamic Causal Model

Attention is a selection process for an external or internal event.Attention orienting is the ability of selecting useful information from a large number of externally input information and a focus of many researchers.Early studies explored the brain mechanism of attention orienting by examining effective and functional connectivity.However,studies on inhibition of return and attentional bias were still based on exploring brain activation and functional connectivity.Therefore,this paper combined a dynamic causal model(DCM)which reveals causal informations between brain regions with functional magnetic resonance imaging(higher spatial resolution than electroencephalogram)to study the inhibition of return among normal people and the attentional bias of lonely individuals.The causal information flow of attentional orienting networks and the neural mechanism were also invesgated.The main work of this dissertation is listed as follows:First,the DCM was used to study the neural mechanism of inhibition of return with cue-target paradigm.We found that the main effect of stimulus onset asynchrony(SOA)mainly activated the right dorsal attention network by three way repeated measures analysis of variance(ANOVA)and this main effect was related to the neural mechanism of inhibition of return.Hence,the DCM analysis was conducted to analyze the effectivity connectivity among visual cortex,intraparietal sulcus and frontal eye field.According to the DCM results,when the SOA is short,the bottom-up connectivity between regions of right dorsal attention network were found.However,both bottomup and top-down information flows between regions of right dorsal attention network were observed when the SOA was long.No differential information flow between dorsal and ventral attention network was found in long SOA and short SOA condition.Second,we used DCM to test whether memory was involved in visual search and further investigated the interaction between memory and attention.According to the results of three way repeated measures ANOVA,we found that dorsolateral prefrontal cortex(DLPFC)activation in the main effect of search type.Further,the random effect analysis indicated the dorsolateral prefrontal cortex(DLPFC)was selectively activated by serial search and deactivated by parallel search.In contrast,right temporoparietal junction(rTPJ)responded positively to all conditions.The DCM results indicated that rTPJ excited by sensory inputs,and that only the top-down connection from DLPFC to rTPJ was modulated by serial search.Conversely,the DLPFC was suppressed by sensory inputs during parallel search.Third,we investigated the attention bias between high loneliness group and low loneliness group when they viewed the mixed picture of social and non-social stimuli.The whole brain analysis reported that when high loneliness group viewed the mixed picture of face and building,the activation strength of fusiform face area(FFA)and inferior parietal lobule was stronger than that of low loneliness group.When we analyzed the probe effect,it was also found that high loneliness had an attention bias for the face probe.Finally,we also used the DCM to explore the causal information flow between FFA,anterior TPJ and posterior TPJ in high and low loneliness groups.We found that the connectivity from the FFA to posterior TPJ in low loneliness group and the bidirectional connectivity between FFA and anterior TPJ in high loneliness group.