Chu Ron K O, Braun Allen R, Meltzer Jed A
University of Toronto, Department of Psychology, 100 St. George Street, 4th Floor, Sidney Smith Hall, Toronto, ON M5S 3G3, Canada ; Rotman Research Institute, Baycrest Centre, 3560 Bathurst St., Toronto, ON M6A 2E1, Canada.
Language Section, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA.
Neuroimage Clin. 2015 Apr 8;8:157-69. doi: 10.1016/j.nicl.2015.03.019. eCollection 2015.
Post-stroke impairment is associated not only with structural lesions, but also with dysfunction in surviving perilesional tissue. Previous studies using equivalent current dipole source localization of MEG/EEG signals have demonstrated a preponderance of slow-wave activity localized to perilesional areas. Recent studies have also demonstrated the utility of nonlinear analyses such as multiscale entropy (MSE) for quantifying neuronal dysfunction in a wide range of pathologies. The current study utilized beamformer-based reconstruction of signals in source space to compare spectral and nonlinear measures of electrical activity in perilesional and healthy cortices. Data were collected from chronic stroke patients and healthy controls, both young and elderly. We assessed relative power in the delta (1-4 Hz), theta (4-7 Hz), alpha (8-12 Hz) and beta (15-30 Hz) frequency bands, and also measured the nonlinear complexity of electrical activity using MSE. Perilesional tissue exhibited a general slowing of the power spectrum (increased delta/theta, decreased beta) as well as a reduction in MSE. All measures tested were similarly sensitive to changes in the posterior perilesional regions, but anterior perilesional dysfunction was detected better by MSE and beta power. The findings also suggest that MSE is specifically sensitive to electrophysiological dysfunction in perilesional tissue, while spectral measures were additionally affected by an increase in rolandic beta power with advanced age. Furthermore, perilesional electrophysiological abnormalities in the left hemisphere were correlated with the degree of language task-induced activation in the right hemisphere. Finally, we demonstrate that single subject spectral and nonlinear analyses can identify dysfunctional perilesional regions within individual patients that may be ideal targets for interventions with noninvasive brain stimulation.
中风后的损伤不仅与结构损伤有关，还与病灶周围存活组织的功能障碍有关。先前使用脑磁图/脑电图信号等效电流偶极子源定位的研究表明，病灶周围区域存在优势慢波活动。最近的研究还证明了诸如多尺度熵（MSE）等非线性分析在量化多种病理状态下神经元功能障碍方面的效用。本研究利用基于波束形成器的源空间信号重建，比较病灶周围和健康皮层电活动的频谱和非线性测量指标。数据收集自年轻和老年的慢性中风患者及健康对照者。我们评估了δ（1 - 4Hz）、θ（4 - 7Hz）、α（8 - 12Hz）和β（15 - 30Hz）频段的相对功率，并使用MSE测量电活动的非线性复杂度。病灶周围组织表现出功率谱普遍减慢（δ/θ增加，β减少）以及MSE降低。所有测试指标对病灶周围后部区域的变化同样敏感，但MSE和β功率能更好地检测病灶周围前部功能障碍。研究结果还表明，MSE对病灶周围组织的电生理功能障碍具有特异性敏感性，而频谱测量指标还额外受到随着年龄增长中央β功率增加的影响。此外，左半球病灶周围的电生理异常与右半球语言任务诱发激活的程度相关。最后，我们证明单受试者频谱和非线性分析可以识别个体患者内功能失调的病灶周围区域，这些区域可能是非侵入性脑刺激干预的理想靶点。
