The human brain is highly plastic.Cognitive training is usually used to modify functional connectivity of brain networks.Moreover,the structures of brain networks may determine its dynamic behavior which is related to...The human brain is highly plastic.Cognitive training is usually used to modify functional connectivity of brain networks.Moreover,the structures of brain networks may determine its dynamic behavior which is related to human cognitive abilities.To study the effect of functional connectivity on the brain dynamics,the dynamic model based on functional connections of the brain and the Hindmarsh–Rose model is utilized in this work.The resting-state fMRI data from the experimental group undergoing abacus-based mental calculation(AMC)training and from the control group are used to construct the functional brain networks.The dynamic behavior of brain at the resting and task states for the AMC group and the control group are simulated with the above-mentioned dynamic model.In the resting state,there are the differences of brain activation between the AMC group and the control group,and more brain regions are inspired in the AMC group.A stimulus with sinusoidal signals to brain networks is introduced to simulate the brain dynamics in the task states.The dynamic characteristics are extracted by the excitation rates,the response intensities and the state distributions.The change in the functional connectivity of brain networks with the AMC training would in turn improve the brain response to external stimulus,and make the brain more efficient in processing tasks.展开更多
为明确无筋超高性能混凝土(Ultra High Performance Concrete,UHPC)单向板和周边支承方板的受弯性能,分别对其进行了跨中局部荷载作用下受弯性能的破坏性试验.基于本文及其他文献的试验结果,考虑钢纤维特征参数的影响,建立了UHPC材料的...为明确无筋超高性能混凝土(Ultra High Performance Concrete,UHPC)单向板和周边支承方板的受弯性能,分别对其进行了跨中局部荷载作用下受弯性能的破坏性试验.基于本文及其他文献的试验结果,考虑钢纤维特征参数的影响,建立了UHPC材料的受拉本构.通过数值分析,提出了无筋UHPC板截面受拉区等效均布应力折减系数k的计算公式.根据试验和分析结果,建立了无筋UHPC单向板和周边支承方板抗弯承载能力的简化计算方法.结果表明:无筋UHPC单向板和周边支承方板均发生由UHPC抗拉性能所控制的受拉破坏.由于UHPC内钢纤维的增强作用,无筋UHPC板的抗弯承载能力和极限变形分别较相应的开裂荷载和开裂变形明显提高且表现出一定的延性破坏特征,但UHPC的受拉塑性尚不足以保证周边支承方板中完全塑性铰线机构的形成,塑性铰线法的上限解不适于预测周边支承方板的极限荷载,而静力法的下限解却能给出精度较高且偏于安全的预测结果;试验结果验证了所提无筋UHPC单向板和周边支承方板极限承载能力简化计算方法的适用性.展开更多
Mathematical calculation usually requires sustained attention to manipulate numbers in the mind,while listening to light music has a relaxing effect on the brain.The differences in the corresponding brain functional n...Mathematical calculation usually requires sustained attention to manipulate numbers in the mind,while listening to light music has a relaxing effect on the brain.The differences in the corresponding brain functional network topologies underlying these behaviors remain rarely known.Here,we systematically examined the brain dynamics of four behaviors(resting with eyes closed and eyes open,tasks of music listening and mental calculation)using 64-channel electroencephalogram(EEG)recordings and graph theory analysis.We developed static and dynamic minimum spanning tree(MST)analysis method and demonstrated that the brain network topology under mental calculation is a more line-like structure with less tree hierarchy and leaf fraction;however,the hub regions,which are mainly located in the frontal,temporal and parietal regions,grow more stable over time.In contrast,music-listening drives the brain to exhibit a highly rich network of star structure,and the hub regions are mainly located in the posterior regions.We then adopted the dynamic dissimilarity of different MSTs over time based on the graph Laplacian and revealed low dissimilarity during mental calculation.These results suggest that the human brain functional connectivity of individuals has unique dynamic diversity and flexibility under various behaviors.展开更多
利用功能磁共振成像(functional Magnetic Resonance Imaging,fMRI)进行脑功能研究是目前的一个热点。现以逻辑计算为认知任务,利用fMRI进行数据采集。采用低频振荡振幅(amplitude of low frequency fluctuation,ALFF)算法分别对14例正...利用功能磁共振成像(functional Magnetic Resonance Imaging,fMRI)进行脑功能研究是目前的一个热点。现以逻辑计算为认知任务,利用fMRI进行数据采集。采用低频振荡振幅(amplitude of low frequency fluctuation,ALFF)算法分别对14例正常人的计算和无任务静息状态的功能磁共振数据进行处理,并做对比分析。观察振幅增强或减弱情况,发现计算任务下相关激活脑区存在低频振荡,逻辑认知的负载也导致了默认(default mode)网络改变;同时针对相关的改变做出了初步探索。展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62276229 and 32071096).
文摘The human brain is highly plastic.Cognitive training is usually used to modify functional connectivity of brain networks.Moreover,the structures of brain networks may determine its dynamic behavior which is related to human cognitive abilities.To study the effect of functional connectivity on the brain dynamics,the dynamic model based on functional connections of the brain and the Hindmarsh–Rose model is utilized in this work.The resting-state fMRI data from the experimental group undergoing abacus-based mental calculation(AMC)training and from the control group are used to construct the functional brain networks.The dynamic behavior of brain at the resting and task states for the AMC group and the control group are simulated with the above-mentioned dynamic model.In the resting state,there are the differences of brain activation between the AMC group and the control group,and more brain regions are inspired in the AMC group.A stimulus with sinusoidal signals to brain networks is introduced to simulate the brain dynamics in the task states.The dynamic characteristics are extracted by the excitation rates,the response intensities and the state distributions.The change in the functional connectivity of brain networks with the AMC training would in turn improve the brain response to external stimulus,and make the brain more efficient in processing tasks.
文摘为明确无筋超高性能混凝土(Ultra High Performance Concrete,UHPC)单向板和周边支承方板的受弯性能,分别对其进行了跨中局部荷载作用下受弯性能的破坏性试验.基于本文及其他文献的试验结果,考虑钢纤维特征参数的影响,建立了UHPC材料的受拉本构.通过数值分析,提出了无筋UHPC板截面受拉区等效均布应力折减系数k的计算公式.根据试验和分析结果,建立了无筋UHPC单向板和周边支承方板抗弯承载能力的简化计算方法.结果表明:无筋UHPC单向板和周边支承方板均发生由UHPC抗拉性能所控制的受拉破坏.由于UHPC内钢纤维的增强作用,无筋UHPC板的抗弯承载能力和极限变形分别较相应的开裂荷载和开裂变形明显提高且表现出一定的延性破坏特征,但UHPC的受拉塑性尚不足以保证周边支承方板中完全塑性铰线机构的形成,塑性铰线法的上限解不适于预测周边支承方板的极限荷载,而静力法的下限解却能给出精度较高且偏于安全的预测结果;试验结果验证了所提无筋UHPC单向板和周边支承方板极限承载能力简化计算方法的适用性.
基金YY thanks for the support from the National Natural Science Foundation of China(81761128011)the Shanghai Municipal Science and Technology Major Project(2018SHZDZX01)ZJ Lab,the program for the Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning.
文摘Mathematical calculation usually requires sustained attention to manipulate numbers in the mind,while listening to light music has a relaxing effect on the brain.The differences in the corresponding brain functional network topologies underlying these behaviors remain rarely known.Here,we systematically examined the brain dynamics of four behaviors(resting with eyes closed and eyes open,tasks of music listening and mental calculation)using 64-channel electroencephalogram(EEG)recordings and graph theory analysis.We developed static and dynamic minimum spanning tree(MST)analysis method and demonstrated that the brain network topology under mental calculation is a more line-like structure with less tree hierarchy and leaf fraction;however,the hub regions,which are mainly located in the frontal,temporal and parietal regions,grow more stable over time.In contrast,music-listening drives the brain to exhibit a highly rich network of star structure,and the hub regions are mainly located in the posterior regions.We then adopted the dynamic dissimilarity of different MSTs over time based on the graph Laplacian and revealed low dissimilarity during mental calculation.These results suggest that the human brain functional connectivity of individuals has unique dynamic diversity and flexibility under various behaviors.
文摘利用功能磁共振成像(functional Magnetic Resonance Imaging,fMRI)进行脑功能研究是目前的一个热点。现以逻辑计算为认知任务,利用fMRI进行数据采集。采用低频振荡振幅(amplitude of low frequency fluctuation,ALFF)算法分别对14例正常人的计算和无任务静息状态的功能磁共振数据进行处理,并做对比分析。观察振幅增强或减弱情况,发现计算任务下相关激活脑区存在低频振荡,逻辑认知的负载也导致了默认(default mode)网络改变;同时针对相关的改变做出了初步探索。
