估计员
相(物质)
同步(交流)
相位同步
滞后
噪音(视频)
数学
灵敏度(控制系统)
连贯性(哲学赌博策略)
统计
物理
计算机科学
人工智能
电子工程
拓扑(电路)
计算机网络
量子力学
组合数学
工程类
图像(数学)
作者
Martin Vinck,Robert Oostenveld,Marijn van Wingerden,Franscesco Battaglia,Cyriel M. A. Pennartz
出处
期刊:NeuroImage
[Elsevier]
日期:2011-04-01
卷期号:55 (4): 1548-1565
被引量:1146
标识
DOI:10.1016/j.neuroimage.2011.01.055
摘要
Phase-synchronization is a manifestation of interaction between neuronal groups measurable from LFP, EEG or MEG signals, however, volume conduction can cause the coherence and the phase locking value to spuriously increase. It has been shown that the imaginary component of the coherency (ImC) cannot be spuriously increased by volume-conduction of independent sources. Recently, it was proposed that the phase lag index (PLI), which estimates to what extent the phase leads and lags between signals from two sensors are nonequiprobable, improves on the ImC. Compared to ImC, PLI has the advantage of being less influenced by phase delays. However, sensitivity to volume-conduction and noise, and capacity to detect changes in phase-synchronization, is hindered by the discontinuity of the PLI, as small perturbations turn phase lags into leads and vice versa. To solve this problem, we introduce a related index, namely the weighted phase lag index (WPLI). Differently from PLI, in WPLI the contribution of the observed phase leads and lags is weighted by the magnitude of the imaginary component of the cross-spectrum. We demonstrate two advantages of the WPLI over the PLI, in terms of reduced sensitivity to additional, uncorrelated noise sources and increased statistical power to detect changes in phase-synchronization. Another factor that can affect phase-synchronization indices is sample-size bias. We show that, when directly estimated, both PLI and the magnitude of the ImC have typically positively biased estimators. To solve this problem, we develop an unbiased estimator of the squared PLI, and a debiased estimator of the squared WPLI.
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