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首页> 外文期刊>Journal of Theoretical Biology >Analysis of the electroencephalographic activity associated with thalamic tumors
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Analysis of the electroencephalographic activity associated with thalamic tumors

机译：与丘脑肿瘤相关的脑电图活动分析

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A physiologically based model of corticothalamic dynamics is used to investigate the electroencephalographic (EEG) activity associated with tumors of the thalamus. Tumor activity is modeled by introducing localized two-dimensional spatial non-uniformities into the model parameters, and calculating the resulting activity via the coupling of spatial eigenmodes. The model is able to reproduce various qualitative features typical of waking eyes-closed EEGs in the presence of a thalamic tumor, such as the appearance of abnormal peaks at theta ( approximate to 3Hz) and spindle ( approximate to 12Hz) frequencies, the attenuation of normal eyes-closed background rhythms, and the onset of epileptic activity, as well as the relatively normal EEGs often observed. The results indicate that the abnormal activity at theta and spindle frequencies arises when a small portion of the brain is forced into an over-inhibited state due to the tumor, in which there is an increase in the firing of (inhibitory) thalamic reticular neurons. The effect is heightened when there is a concurrent decrease in the firing of (excitatory) thalamic relay neurons, which are in any case inhibited by the reticular ones. This is likely due to a decrease in the responsiveness of the peritumoral region to cholinergic inputs from the brainstem, and a corresponding depolarization of thalamic reticular neurons, and hyperpolarization of thalamic relay neurons, similar to the mechanism active during slow-wave sleep. The results indicate that disruption of normal thalamic activity is essential to generate these spectral peaks. Furthermore, the present work indicates that high-voltage and epileptiform EEGS are caused by a tumor-induced local over-excitation of the thalamus, which propagates to the cortex. Experimental findings relating to local over-inhibition and over-excitation are discussed. It is also confirmed that increasing the size of the tumor leads to greater abnormalities in the observable EEG. The usefulness of EEG for localizing the tumor is investigated. (C) 2004 Elsevier Ltd. All rights reserved.
机译：基于生理学的皮层丘脑动力学模型用于研究与丘脑肿瘤相关的脑电图（EEG）活性。通过将局部二维空间不均匀性引入模型参数，并通过空间特征模式的耦合来计算所得的活动来对肿瘤活动进行建模。该模型能够重现丘脑肿瘤存在时醒眼的典型EEG的各种定性特征，例如在θ（约3Hz）和纺锤体（约12Hz）频率处出现异常峰，正常的闭眼背景节律，癫痫发作的发作以及经常观察到的相对正常的脑电图。结果表明，当一小部分大脑由于肿瘤被迫进入过度抑制状态时，在theta和纺锤频率处会出现异常活动，其中（抑制性）丘脑网状神经元的放电增加。当（兴奋性）丘脑中继神经元的放电同时减少时，这种效果会增强，而在任何情况下都受到网状神经元抑制。这可能是由于肿瘤周围区域对来自脑干的胆碱能输入的反应性降低，以及丘脑网状神经元相应去极化和丘脑中继神经元超极化所致，类似于慢波睡眠中活跃的机制。结果表明，正常丘脑活动的破坏对于产生这些光谱峰是必不可少的。此外，目前的工作表明，高电压和癫痫样的EEGS是由肿瘤引起的丘脑局部过度兴奋引起的，丘脑扩散到皮质。讨论了有关局部过度抑制和过度兴奋的实验结果。还证实增加肿瘤的大小导致可观察到的EEG中更大的异常。研究了脑电图对肿瘤定位的有用性。 （C）2004 Elsevier Ltd.保留所有权利。

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