David Olivier, Kilner James M, Friston Karl J
Wellcome Department of Imaging Neuroscience, Institute of Neurology, 12 Queen Square, London WC1N 3BG, UK.
Neuroimage. 2006 Jul 15;31(4):1580-91. doi: 10.1016/j.neuroimage.2006.02.034. Epub 2006 Apr 24.
Cortical responses, recorded by electroencephalography and magnetoencephalography, can be characterized in the time domain, to study event-related potentials/fields, or in the time-frequency domain, to study oscillatory activity. In the literature, there is a common conception that evoked, induced, and on-going oscillations reflect different neuronal processes and mechanisms. In this work, we consider the relationship between the mechanisms generating neuronal transients and how they are expressed in terms of evoked and induced power. This relationship is addressed using a neuronally realistic model of interacting neuronal subpopulations. Neuronal transients were generated by changing neuronal input (a dynamic mechanism) or by perturbing the systems coupling parameters (a structural mechanism) to produce induced responses. By applying conventional time-frequency analyses, we show that, in contradistinction to common conceptions, induced and evoked oscillations are perhaps more related than previously reported. Specifically, structural mechanisms normally associated with induced responses can be expressed in evoked power. Conversely, dynamic mechanisms posited for evoked responses can induce responses, if there is variation in neuronal input. We conclude, it may be better to consider evoked responses as the results of mixed dynamic and structural effects. We introduce adjusted power to complement induced power. Adjusted power is unaffected by trial-to-trial variations in input and can be attributed to structural perturbations without ambiguity.
通过脑电图和脑磁图记录的皮层反应，可以在时域中进行表征以研究事件相关电位/场，或者在时频域中进行表征以研究振荡活动。在文献中，有一种普遍的观念认为，诱发振荡、诱导振荡和持续振荡反映了不同的神经元过程和机制。在这项工作中，我们考虑了产生神经元瞬变的机制之间的关系，以及它们如何以诱发功率和诱导功率的形式表现出来。我们使用一个相互作用的神经元亚群的神经现实模型来探讨这种关系。通过改变神经元输入（一种动态机制）或扰动系统耦合参数（一种结构机制）来产生诱导反应，从而产生神经元瞬变。通过应用传统的时频分析，我们表明，与普遍观念相反，诱导振荡和诱发振荡之间的关系可能比以前报道的更为密切。具体而言，通常与诱导反应相关的结构机制可以在诱发功率中表现出来。相反，如果神经元输入存在变化，为诱发反应假定的动态机制也可以诱导反应。我们得出结论，将诱发反应视为混合动态和结构效应的结果可能会更好。我们引入调整功率来补充诱导功率。调整功率不受输入试验间变化的影响，并且可以明确地归因于结构扰动。
