Defining seeds is the first step in assessing functional connectivity between separate brain regions.Circular analysis is often a serious concern when defining ROIs.It was considered as circular analysis that seeds we...Defining seeds is the first step in assessing functional connectivity between separate brain regions.Circular analysis is often a serious concern when defining ROIs.It was considered as circular analysis that seeds were localized on the basis of activations in fMRI data and the functional connectivity among these seeds was measured by using the same data.Such circularity was reported to contaminate results because the margin of detected activations can be affected by noise in the data.Therefore,using independent data for seed selection was advocated.For example,suppose that datasets A and B are independent.Activations are first detected in dataset A through statistical mapping,and then these activations are used to localize seeds for assessing functional connectivity in dataset B.However,localizing seeds only on the basis of an independent source without referring to the intrinsic features of the fMRI data to be analyzed may be inappropriate for assessing functional connectivity.This study demonstrates how different spatial locations and seed scopes influence the results of functional connectivity in task-state fMRI data when these choices meet independence requirements.The independence of analysis does not rely on whether seeds are exogenous or endogenous for the data to be analyzed.Activation and connectivity analyses have inherently independent natures.展开更多
针对人在回路中感兴趣区ROI(regions of interest)编码问题,提出了一种感兴趣区动态编码方法,该方法利用率失真函数凸函数特性,对处于相同编码层ROI、BG区域分别设定不同目标码率,在各编码层控制ROI和背景区码率,使得ROI获得比较高的编...针对人在回路中感兴趣区ROI(regions of interest)编码问题,提出了一种感兴趣区动态编码方法,该方法利用率失真函数凸函数特性,对处于相同编码层ROI、BG区域分别设定不同目标码率,在各编码层控制ROI和背景区码率,使得ROI获得比较高的编码质量,并允许在编码过程中任意指定、修改感兴趣区域及其优先级,实验结果表明满足了远程操控过程中动态改变ROI的需求。展开更多
基金This research was funded by the National Key R&D Program of China[Grant Nos.2018YFC2001400 and 2018YFC2001700]the National Natural Science Foundation of China[Grant No.81972160]the Beijing Natural Science Foundation[Grant No.17L20019].
文摘Defining seeds is the first step in assessing functional connectivity between separate brain regions.Circular analysis is often a serious concern when defining ROIs.It was considered as circular analysis that seeds were localized on the basis of activations in fMRI data and the functional connectivity among these seeds was measured by using the same data.Such circularity was reported to contaminate results because the margin of detected activations can be affected by noise in the data.Therefore,using independent data for seed selection was advocated.For example,suppose that datasets A and B are independent.Activations are first detected in dataset A through statistical mapping,and then these activations are used to localize seeds for assessing functional connectivity in dataset B.However,localizing seeds only on the basis of an independent source without referring to the intrinsic features of the fMRI data to be analyzed may be inappropriate for assessing functional connectivity.This study demonstrates how different spatial locations and seed scopes influence the results of functional connectivity in task-state fMRI data when these choices meet independence requirements.The independence of analysis does not rely on whether seeds are exogenous or endogenous for the data to be analyzed.Activation and connectivity analyses have inherently independent natures.
文摘针对人在回路中感兴趣区ROI(regions of interest)编码问题,提出了一种感兴趣区动态编码方法,该方法利用率失真函数凸函数特性,对处于相同编码层ROI、BG区域分别设定不同目标码率,在各编码层控制ROI和背景区码率,使得ROI获得比较高的编码质量,并允许在编码过程中任意指定、修改感兴趣区域及其优先级,实验结果表明满足了远程操控过程中动态改变ROI的需求。
