Anatomical Pathways Between Human Dorsal And Ventral Attention Network

Objective:According to early neuroimaging studies,attention is thought to be controlled by two functional sub-networks: the dorsal attention network(DAN)being responsible for endogenous goal-driven and exogenous orienting of attention;and the ventral network(VAN)involving in reorienting attention to salient stimuli.Besides the functional specialization of the DAN and VAN,these two attention sub-networks were also dynamically interacted to determine which aspects of sensory information will be perceived.Both the task-evoked and the resting-state functional magnetic resonance imaging(fMRI)studies indicate that there are functional hubs connecting between DAN and VAN,including the right posterior inferior frontal gyrus(pIFG),anterior middle frontal gyrus(aMFG),and superior marginal gyrus(SMG).However,the anatomical bases between DAN and VAN are unknown,which are critical for understanding the information processing mechanism of the attention system.To identify anatomical connections between DAN and VAN,we first extracted the functional hubs between the two attention networks to track the white matter fibers of these hubs based on two independent cohorts;then the patterns of anatomical connection between DAN and VAN via these hubs were investigated;and finally correlations between anatomical and functional connection strengths of these hubs were explored.Materials and Methods:We used the functional and structural MRI data of 100 subjects from human connectome project(HCP)and 50 healthy adult subjects collected from our center.First,the core brain regions of the DAN and VAN were obtained according to the brain activation meta-analysis,respectively.The functional connections of these brain regions were then calculated,and conjunction analysis was carried out on the functional connections of these brain regions to extract hubs that were highlysynchronized with both DAN and VAN in spontaneous brain activity.The generalized q-space imaging(GQI)reconstruction technique and the streamline deterministic tracking algorithm were used to construct the white matter fiber bundles for each hub;the patterns of anatomic and functional connections of these hubs with the DAN/VAN were analyzed;and the correlation between anatomical and functional connection strengths of each hub with the attention network was investigated.In order to validate the robustness of the results,a variety of comparative verification methods were used in this study,such as validating the results from different subgroups of the HCP cohort,those between different acquisition time points,and those from the HCP cohorts and our center.Results:In this study,three hubs with positive functional connection to both DAN and VAN were repeatedly identified,including the right posterior inferior frontal gyrus(pIFG),right anterior middle frontal gyrus(aMFG),right superior marginal gyrus(SMG).Each hub region showed its unique anatomical connection pattern with the DAN and VAN.Taking brain regions of the DAN as an example,the pIFG was mainly connected to the right superior frontal gyrus dorsolateral area,the right middle frontal gyrus ventrolateral area,and the right precentral gyrus caudal ventrolateral area;the aMFG with the left middle frontal gyrus ventral area,the right middle frontal gyrus ventrolateral area,the right precentral gyrus caudal ventrolateral area,and the right inferior frontal gyrus inferior frontal sulcus;and the SMG with the right inferior parietal lobule rostrodorsal area 40(PFt),right superior parietal lobule intraparietal area 7(hIP3),and right lateral superior parietal lobule.Taking brain regions of the VAN as another example,the pIFG was mainly connected with the right inferior frontal gyrus ventral area and the right middle frontal gyrus inferior frontal junction;the aMFG with the right middle frontal gyrus ventral area and the right middle frontal gyrus inferior frontal junction;and the SMG with the right inferior parietal lobule caudal(PFm)and rostroventral area 40(PFop).The anatomical connection patterns were highly similar between the discovery group and any other validation groups.The patterns between anatomical and functional connections of each hub region werealso similar,which is further supported by the significant correlation between its anatomical and functional connection strengths.These findings were also confirmed in all validation datasets.Conclusion:In this study,we discovered that the DAN and VAN was anatomically connected to each other via functional hubs;each hub had its unique anatomical connection pattern with the attention network;and the anatomical and functional connection strengths of each hub were correlated.These findings are helpful to understand the information exchange mechanisms between the DAN and VAN.