Study On Spatiotemporal Features Of Human Brain Functional Connectivity Under The Naturalistic Condition Based On Magnetic Resonance Imaging

The brain is a complex system that contains rich spatiotemporal information.Functional magnetic resonance imaging(f MRI),as a non-invasive imaging technology,has good temporal and spatial resolution and has been widely used in brain research.Brain research based on f MRI is usually divided into two areas: resting-state f MRI(rsf MRI)and task-evoked f MRI(tf MRI).In recent years,the naturalistic condition has been regarded as an intermediate state(or condition)between the rsf MRI and the tf MRI,which not only has richer information than the rsf MRI but is also easier to manipulate than the tf MRI.Although some studies explored brain functions in the naturalistic condition,it is still unclear how stable various functional connectivities are and how they differ from functional connectivities in the rsf MRI.In addition,an increasing number of studies have shown that the blood oxygen level-dependent(BOLD)signal in white matter can also be used to measure brain function activities.However,the impact of naturalistic condition on the BOLD signal in white matter has not yet been clarified.First,this study used clustering to obtain gray and white matter functional templates of regions of interest(ROI)and network-levels,respectively.Then,individual identification accuracy and Intraclass correlation coefficients were calculated for functional connectivity(FC)and inter-subject functional connectivity(ISFC)within the whole brain(gray matter,white matter,and between gray and white matter)to explore their stability under different movies.Finally,the effect of data volume on the stability of FC and ISFC was examined by truncating time series.The study found that FC exhibited strong consistency between movies,and ISFC showed a certain degree of stability.In addition,it was found that the stability growth of FC and ISFC across the whole brain began to slow down when the duration of the concatenated movies exceeded 16 minutes.The results suggest that FC and ISFC between different movies exhibit a certain degree of stability,which makes it possible to integrate different movie contents for researching on naturalistic condition.In addition,this study used the gray and white matter functional templates from the previous study to calculate the FC and ISFC of the whole brain under movie-watching and resting-state conditions,and explored the differences between the two conditions using statistical tests.The Intraclass correlation coefficients were also calculated for FC and ISFC in both conditions to demonstrate their reliabilities.Furthermore,the Pearson correlation coefficients were calculated between static and dynamic functional connectivity indices and between the movie-watching and resting-state conditions to describe their relationships.The study found that naturalistic condition significantly affected the FC of the whole brain,but the improvement in ISFC was not significant.In addition,the Intraclass correlation coefficients of FC and ISFC were generally higher during movie-watching than at the resting-state.Under naturalistic condition,static and dynamic ISFC showed a weak negative correlation,while there was no correlation between the two during the resting-state.These results suggested that naturalistic condition cause significant changes in FC and have higher stability than the resting-state,and enhance ISFC to some extent.Therefore,naturalistic condition plays an important role in obtaining rich spatiotemporal information of the brain.