von Ellenrieder Nicolás, Dan Jonathan, Frauscher Birgit, Gotman Jean
Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, Quebec, H3A 2B4, Canada.
Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, Quebec, H3A 2B4, Canada; École Polytechnique, Université Libre de Bruxelles, 50 Avenue F. D. Roosevelt, 1050 Bruxelles, Belgium.
Neuroimage. 2016 Sep;138:123-133. doi: 10.1016/j.neuroimage.2016.05.067. Epub 2016 Jun 1.
We investigate to what degree the synchronous activation of a smooth patch of cortex is necessary for observing EEG scalp activity. We perform extensive simulations to compare the activity generated on the scalp by different models of cortical activation, based on intracranial EEG findings reported in the literature. The spatial activation is modeled as a cortical patch of constant activation or as random sets of small generators (0.1 to 3cm(2) each) concentrated in a cortical region. Temporal activation models for the generation of oscillatory activity are either equal phase or random phase across the cortical patches. The results show that smooth or random spatial activation profiles produce scalp electric potential distributions with the same shape. Also, in the generation of oscillatory activity, multiple cortical generators with random phase produce scalp activity attenuated on average only 2 to 4 times compared to generators with equal phase. Sparse asynchronous cortical generators can produce measurable scalp EEG. This is a possible explanation for seemingly paradoxical observations of simultaneous disorganized intracranial activity and scalp EEG signals. Thus, the standard interpretation of scalp EEG might constitute an oversimplification of the underlying brain activity.
我们研究了皮质平滑区域的同步激活对于观察脑电图头皮活动的必要程度。基于文献中报道的颅内脑电图研究结果，我们进行了大量模拟，以比较不同皮质激活模型在头皮上产生的活动。空间激活被建模为恒定激活的皮质区域或集中在皮质区域的随机小发生器集合（每个面积为0.1至3平方厘米）。产生振荡活动的时间激活模型在整个皮质区域要么是等相位，要么是随机相位。结果表明，平滑或随机的空间激活模式会产生形状相同的头皮电位分布。此外，在产生振荡活动时，具有随机相位的多个皮质发生器产生的头皮活动平均仅比具有等相位的发生器衰减2至4倍。稀疏的异步皮质发生器可以产生可测量的头皮脑电图。这可能解释了同时出现的颅内活动紊乱和头皮脑电图信号这一看似矛盾的现象。因此，头皮脑电图的标准解释可能过度简化了潜在的脑活动。
