Distinguishing the evoked response from phase reset: A comment to Makinen et al.
Distinguishing the evoked response from phase reset: A comment to Makinen et al.
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DOI：
10.1016/j.neuroimage.2005.08.041
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发表时间：
2006-02-01
期刊：
影响因子：
5.7
通讯作者：
Gruber, WR
中科院分区：
文献类型：
--
作者：
Klimesch, W;Hanslmayr, S;Gruber, WR
Makinen等人[Makinen，V.，Tiitinen，H.，May，P.，2005.听觉事件相关反应的产生独立于正在进行的大脑活动。Neuroimage 24，961 - 968]建议使用振幅方差来区分诱发响应与相位重置。因为他们的数据并没有显示出振幅方差的下降，他们得出结论，ERP是由“独立于正在进行的大脑活动的过程和添加剂”产生的。“我们认为，这一结论是不成熟的，因为对事件相关的振荡调制过程的假设是不切实际的。一个现实的相位重置模型必须考虑至少两个参数，相位重置的程度（或“相位浓度”）和幅度变化（事件相关的幅度增加或减少）。与模拟数据，我们表明，一个变量的幅度大小增加幅度方差和掩模的相位复位的影响。另一方面，在没有相位重置的情况下，与事件相关的幅度减小导致方差急剧下降。此外，特定于频率的相位重置的模拟示出了方差的下降，该方差可能太小而不能凭经验检测。因此，我们得出结论，振幅方差是不能区分诱发反应的相位重置。(c)2005年爱思唯尔公司All rights reserved.
Makinen et al. [Makinen, V., Tiitinen, H., May, P., 2005. Auditory event-related responses are generated independently of ongoing brain activity. Neuroimage 24, 961 -968] suggest the use of amplitude variance to distinguish the evoked response from phase reset. Because their data do not exhibit a drop in amplitude variance, they conclude that ERPs are generated by 'processes separate from and additive to ongoing brain activity.' We argue that this conclusion is premature because of unrealistic assumptions about the processes underlying an event-related modulation of oscillations. A realistic phase reset model has to consider at least two parameters, degree of phase reset (or 'phase concentration') and amplitude change (event-related increase or decrease in amplitude). With simulated data, we show that a variable increase in amplitude size increases amplitude variance and masks the influence of a phase reset. On the other hand, an event-related decrease in amplitude without a phase reset leads to a sharp drop in variance. Furthermore, simulation of a frequency-specific phase reset shows a drop in variance that may be too small to be detected empirically. Thus we conclude that amplitude variance is not capable of distinguishing the evoked response from phase reset. (c) 2005 Elsevier Inc. All rights reserved.