Traveling waves and trial averaging: The nature of single-trial and averaged brain responses in large-scale cortical signals
Traveling waves and trial averaging: The nature of single-trial and averaged brain responses in large-scale cortical signals
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DOI：
10.1016/j.neuroimage.2013.01.016
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发表时间：
2013-06-01
期刊：
影响因子：
5.7
通讯作者：
van Leeuwen, Cees
中科院分区：
文献类型：
--
作者：
Alexander, David M.;Jurica, Peter;van Leeuwen, Cees
分析单次脑活动仍然是神经科学中一个具有挑战性的问题。我们通过关注试验内诱发脑活动中的全局同步场，而不是试验平均诱发反应（ER）中的局部峰值，来解决这个问题。我们分析了三种测量模式的数据，每种测量模式都具有不同的空间分辨率：脑磁图（MEG），脑电图（EEG）和皮层脑电图（ECoG）。我们首先根据试验中相位和振幅分量的总和来表征ER。两者都有助于ER，正如预期的那样，但ER地形主要由相位分量。这意味着观察到的交叉试验相位的形貌不一定反映试验内的相位形貌。为了评估试验内相位的组织，通过计算相位梯度来量化行波（TW）分量。TW是间歇性的，但普遍存在的试验内诱发脑活动。在大多数任务相关的时间和频率，内试验阶段的地形更好地描述了TW比试验平均阶段。TW分量的试平均值也再现了ER的地形;我们认为ER地形在很大程度上是TW行为的平均值。这些发现在三种测量模式中是一致的。我们的结论是，虽然相位是至关重要的了解地形的事件相关的活动，初步步骤整理皮质信号的试验可以掩盖TW组件在大脑活动，并导致低估的连贯运动的皮质领域。(C)2013 Elsevier Inc. All rights reserved.
Analyzing single trial brain activity remains a challenging problem in the neurosciences. We gain purchase on this problem by focusing on globally synchronous fields in within-trial evoked brain activity, rather than on localized peaks in the trial-averaged evoked response (ER). We analyzed data from three measurement modalities, each with different spatial resolutions: magnetoencephalogram (MEG), electroencephalogram (EEG) and electrocorticogram (ECoG). We first characterized the ER in terms of summation of phase and amplitude components over trials. Both contributed to the ER, as expected, but the ER topography was dominated by the phase component. This means the observed topography of cross-trial phase will not necessarily reflect the phase topography within trials. To assess the organization of within-trial phase, traveling wave (TW) components were quantified by computing the phase gradient. TWs were intermittent but ubiquitous in the within-trial evoked brain activity. At most task-relevant times and frequencies, the within-trial phase topography was described better by a TW than by the trial-average of phase. The trial-average of the TW components also reproduced the topography of the ER; we suggest that the ER topography arises, in large part, as an average over TW behaviors. These findings were consistent across the three measurement modalities. We conclude that, while phase is critical to understanding the topography of event-related activity, the preliminary step of collating cortical signals across trials can obscure the TW components in brain activity and lead to an underestimation of the coherent motion of cortical fields. (C) 2013 Elsevier Inc. All rights reserved.