【作者】 胡鹏；

【导师】 Bharat Bhusan Biswal；

【作者基本信息】 电子科技大学 ， 电子信息（专业学位）， 2023， 硕士

【摘要】 大脑是一个复杂的系统,包含着丰富的时空信息。功能磁共振成像作为一种非侵入式的成像技术,在时间和空间分辨率上具有较好的效果,因而目前已被广泛应用于大脑研究。基于功能磁共振成像对大脑功能的研究通常在两个方面,一是静息态功能磁共振,二是任务态功能磁共振。近些年来,自然条件被认为是介于静息态和任务态的一种中间状态(或条件)。自然条件不仅比静息态有更丰富的信息,而且比任务态更易操作。目前虽然有一些研究利用自然条件探究大脑功能,但是各种功能连接的稳定性以及与静息态之间功能连接的差异表现如何,仍然不明。此外,越来越多的研究表明白质的血氧水平依赖信号可以表达大脑功能活动,然而自然条件对白质功能信号的影响尚未被阐明。本文首先聚类得到了感兴趣区(Region of Interest,ROI)水平和网络水平的灰质和白质功能模板,然后计算了全脑(灰质、白质以及灰质和白质之间)中功能连接(Functinal Connectivity,FC)和被试间功能连接(Inter-subject Functional Connectivity,ISFC)的个体识别准确率和类内相关系数用于探究在不同电影之间的稳定性。最后我们通过截取时间序列探究了数据量对FC和ISFC稳定性的影响。研究发现FC表现出了较强的电影间一致性,并且ISFC也表现出了一定程度的稳定性。此外,本研究发现在拼接的电影时长大于16分钟时,全脑的FC和ISFC稳定性增长开始减缓。结果表明在不同电影间FC和ISFC具有一定的稳定性,这使得整合不同的电影内容用于研究自然条件成为可能。此外,本文采用了上一研究的灰质和白质功能模板,计算得到观影和静息态下全脑的FC和ISFC,并通过统计检验探究了两种条件之间的差异。然后,在自然条件和静息态中计算了FC和ISFC的类内相关系数,以讨论两种状态间的可靠性差异。此外,通过在静态和动态功能连接指标之间以及自然条件和静息态之间计算Pearson相关系数,阐述他们之间的关联性。研究发现,自然条件对全脑FC有显著地影响,但自然条件对ISFC的提升并不具有显著性。此外,观看电影时FC和ISFC的类内相关系数普遍高与静息态。在自然条件下,静态和动态ISFC呈弱负相关性,静息态下两者并无相关。结果表明,自然条件引起了显著的FC变化且稳定性要高于静息态,而且自然条件也在一定程度上增强了ISFC。因此,自然条件在获取大脑丰富时空信息中有着重要的作用。更多还原

【Abstract】 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.更多还原