A novel mechanism for evoked responses in the human brain
A novel mechanism for evoked responses in the human brain
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DOI：
10.1111/j.1460-9568.2007.05553.x
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发表时间：
2007-05-01
影响因子：
3.4
通讯作者：
Curio, Gabriel
中科院分区：
文献类型：
--
作者：
Nikulin, Vadim V.;Linkenkaer-Hansen, Klaus;Curio, Gabriel
脑磁图和脑电图诱发反应是人脑认知和知觉过程的主要实时客观测量。两种机制（加性活性和相位重置）一直存在争议，并被认为是诱发反应的唯一可能解释。在这里，我们提出的理论和经验证据的第三机制有助于产生诱发反应。有趣的是，这种机制可以完全从没有刺激的自发振荡的特征中推断出来。我们发现，静止状态下神经元α振荡的振幅波动与脑磁图中正在进行的活动的平均值的变化有关，我们将这种现象称为与α振荡相关的基线偏移。当刺激调节α振荡的振幅时，基线位移成为产生诱发反应的新机制的基础；几次试验的平均导致振荡分量的抵消，但基线位移仍然存在，这引起了诱发反应。我们提出，与α振荡相关的基线移位的存在可以通过与α振荡产生相关的内向和外向神经元电流的不对称流动来解释。我们的发现与绝大多数涉及知觉、认知和运动活动的脑电图和脑磁图研究相关。
Magnetoencephalographic and electroencephalographic evoked responses are primary real-time objective measures of cognitive and perceptual processes in the human brain. Two mechanisms (additive activity and phase reset) have been debated and considered as the only possible explanations for evoked responses. Here we present theoretical and empirical evidence of a third mechanism contributing to the generation of evoked responses. Interestingly, this mechanism can be deduced entirely from the characteristics of spontaneous oscillations in the absence of stimuli. We show that the amplitude fluctuations of neuronal alpha oscillations at rest are associated with changes in the mean value of ongoing activity in magnetoencephalography, a phenomenon that we term baseline shifts associated with alpha oscillations. When stimuli modulate the amplitude of alpha oscillations, baseline shifts become the basis of a novel mechanism for the generation of evoked responses; the averaging of several trials leads to a cancellation of the oscillatory component but the baseline shift remains, which gives rise to an evoked response. We propose that the presence of baseline shifts associated with alpha oscillations can be explained by the asymmetric flow of inward and outward neuronal currents related to the generation of alpha oscillations. Our findings are relevant to the vast majority of electroencephalographic and magnetoencephalographic studies involving perceptual, cognitive and motor activity.