The Brain Networks In Resting State And Its Relationship With Attention

Our brain is a complex network of interconnected regions. Within this brain network, information is constantly processed and integrated between specialized, spatially distributed but functionally linked brain regions with coherent temporal dynamics. This integration of information is a never-ending process that goes on even when we are at rest. This ongoing integration of information enables us to evaluate the world around us and to respond quickly and flexibly to complex situations. Recent studies have shown that the functional connections of the brain network are organized in a highly efficient small-world manner. A small-world organization of the brain network suggests a high level of local neighborhood clustering, responsible for efficient local information processing, together with the existence of several long-distance connections that ensure a high level of global communication efficiency across the network and integration of information between the different regions of the brain. Neuroimaging researches have suggested that the organization of the brain networks is correlated with the cognitive functions.Attention is a high order cognitive function in human beings. It refers to both the preparedness for and selection of certain aspects of our physical environment or some ideas in our mind. Functional neuroimaging studies have indicated that there were three key subsystems of attention, i.e. alerting, orienting, and executive control. In general, alerting is defined as achieving and maintaining a state of high sensitivity; orienting refers to the selection of sensory information; and executive control is involved with the processing of cognitively incongruent stimuli or conflict. These subnetworks of attention have been shown to differ in their anatomy substrates and neurochemical pathways. Because of the limited capacity of the brain to handle information, the appropriate selection of information for processing becomes especially critical in our daily life. With more research tools in neuropsychological and neuroimaging studies becoming available. In this study, using resting state fMRI, we calculated the brain functional networks in resting state and its relationship with attention function to explore the neuronal basis of attention in resting state. Part1:The default mode network in resting state and its heritabilityObjective:The default mode network (DMN) is thought to characterize basal neural activity and has been considered as one of the most intriguing puzzles in cognitive neuroscience. Previous studies have found that the key regions within the DMN are highly interconnected and causally interacted. Here, we explored how genetic control over the causal information flow within the DMN during resting state.Materials and Methods:Forty-six pairs (25MZ,21DZ) of twins participated in this study. We collected the resting state fMRI using3.0T scanner and conducted the DCM analysis with the SPM8software. Then a structural equation modal was set to calculated the heritability of default mode network.Results:Model comparison procedures favored a full-connected model. The ACE modal was discovered in the analysis of structural equation modal comparison. Heritability for the effective connectivity of the DMN was0.54.Conclusion:Establishing the heritability of default-mode effective connectivity authorizes the use of resting-state networks as endophenotypes or intermediate phenotypes in the search for the genetic roots of psychiatric or neurological illnesses. Furthermore, identification of the genes that influence the intrinsic functional architecture of the human brain would represent a significant advance for basic neuroscience, independent of the ramifications for brain disorders. Part2:The relationship between spontaneous neuronal activity and intersubject variations in executive control of attentionObjective:Executive control of attention regulates our thoughts, emotion and behavior. Individual differences in executive control are associated with task-related differences in brain activity. In this study, we explored whether attentional differences depend on endogenous (resting state) brain activity and to what extent regional fluctuations and functional connectivity contribute to individual variations in executive control processing. Materials and Methods:Fifty-eight normal subjects participated in this study. Resting-state fMRI data and behavioral data of ANT were collected using3.0T scanner. The ALFF and functional connectivity was calculated for each voxel in the human brain. Then a regression analysis was performed between the executive control scores and ALFF/functional connectivity to explore the contribution of ALFF/functional connectivity in predicting the intersubject variations in executive control of attention.Results:We found that ALFF in the right precuneus (PCUN) and the medial part of left superior frontal gyrus (msFC) was significantly correlated with the efficiency of executive control processing. Crucially, the strengths of functional connectivity between the right PCUN/left msFC and distributed brain regions, including the left fusiform gyrus, right inferior frontal gyrus, left superior frontal gyrus and right precentral gyrus, were correlated with individual differences in executive performance. Together, the ALFF and functional connectivity accounted for67%of the variability in behavioral performance. Moreover, the strength of functional connectivity between specific regions could predict more individual variability in executive control performance than regionally specific fluctuations.Conclusion:In conclusion, our findings suggest that spontaneous brain activity may reflect or underpin executive control of attention. It will provide new insights into the origins of inter-individual variability in human executive control processing. Part3:The relationship between attention and the brain functional networks in resting stateObjective:Attention is a crucial brain function for human beings. Using neuropsychological paradigms and task-based functional brain imaging, previous studies have indicated that widely distributed brain regions are engaged in three distinct attention subsystems:alerting, orienting and executive control (EC).In this study, we explored the potential relationship between intrinsic brain networks and the performance of alerting, orienting and EC in normal individuals. Materials and Methods:The resting-state images and behavioral data from attention network test (ANT) task were collected in59healthy subjects. Graph analysis was conducted to obtain the characteristics of functional brain networks and linear regression analyses were used to explore the relationships between the intrinsic network features and behavioral performance of the three attentional components.Results:We found that there was no significant relationship between the attentional performance and the global measures, while the attentional performance was influenced by specific local regional efficiency. These regions related to the scores of alerting, orienting and EC largely overlapped with the regions activated in previous task-related functional imaging studies. In addition, the strong associations between the attentional performance and specific regional efficiency suggested that the resting state activity could predict the attention efficiency.Conclusion:We concluded that the intrinsic activity of the human brain could reflect the processing efficiency of the attention system. Our findings revealed a robust evidence of an efficiently organized resting-state functional brain network for highly productive cognitions.