Laboratory of Cognitive and Computational Neuroscience (UCM-UPM), Centre for Biomedical Technology Madrid, Spain ; Department of Applied Physics III, Faculty of Physics, Complutense University of Madrid Madrid, Spain.
MEG Unit, Brain Imaging Center, Goethe University Frankfurt, Germany ; Max-Planck Institute for Brain Research Frankfurt, Germany ; Institute of Computer Science, Faculty of Mathematics and Computer Science, University of Tartu Tartu, Estonia.
Front Aging Neurosci. 2013 Dec 27;5:100. doi: 10.3389/fnagi.2013.00100. eCollection 2013.
The neurophysiological changes associated with Alzheimer's Disease (AD) and Mild Cognitive Impairment (MCI) include an increase in low frequency activity, as measured with electroencephalography or magnetoencephalography (MEG). A relevant property of spectral measures is the alpha peak, which corresponds to the dominant alpha rhythm. Here we studied the spatial distribution of MEG resting state alpha peak frequency and amplitude values in a sample of 27 MCI patients and 24 age-matched healthy controls. Power spectra were reconstructed in source space with linearly constrained minimum variance beamformer. Then, 88 Regions of Interest (ROIs) were defined and an alpha peak per ROI and subject was identified. Statistical analyses were performed at every ROI, accounting for age, sex and educational level. Peak frequency was significantly decreased (p < 0.05) in MCIs in many posterior ROIs. The average peak frequency over all ROIs was 9.68 ± 0.71 Hz for controls and 9.05 ± 0.90 Hz for MCIs and the average normalized amplitude was (2.57 ± 0.59)·10(-2) for controls and (2.70 ± 0.49)·10(-2) for MCIs. Age and gender were also found to play a role in the alpha peak, since its frequency was higher in females than in males in posterior ROIs and correlated negatively with age in frontal ROIs. Furthermore, we examined the dependence of peak parameters with hippocampal volume, which is a commonly used marker of early structural AD-related damage. Peak frequency was positively correlated with hippocampal volume in many posterior ROIs. Overall, these findings indicate a pathological alpha slowing in MCI.
与阿尔茨海默病（AD）和轻度认知障碍（MCI）相关的神经生理变化包括低频活动的增加，这可以通过脑电图或脑磁图（MEG）来测量。谱测量的一个相关特性是阿尔法峰值，它对应于主导的阿尔法节律。在这里，我们研究了 27 名 MCI 患者和 24 名年龄匹配的健康对照者的 MEG 静息状态阿尔法峰值频率和幅度值的空间分布。用线性约束最小方差波束形成器在源空间重建功率谱。然后，定义了 88 个感兴趣区域（ROI），并为每个 ROI 和受试者确定了一个阿尔法峰值。在每个 ROI 上进行了统计分析，考虑了年龄、性别和教育水平。在许多后头部 ROI 中，MCI 的峰值频率显著降低（p<0.05）。所有 ROI 的平均峰值频率为对照组 9.68±0.71 Hz，MCI 组 9.05±0.90 Hz，平均归一化幅度为对照组 2.57±0.59·10(-2)，MCI 组 2.70±0.49·10(-2)。年龄和性别也被发现对阿尔法峰值有影响，因为在后部 ROI 中，女性的峰值频率高于男性，而在额部 ROI 中，峰值频率与年龄呈负相关。此外，我们还检查了峰值参数与海马体积的依赖性，海马体积是早期结构 AD 相关损伤的常用标志物。在许多后头部 ROI 中，峰值频率与海马体积呈正相关。总体而言，这些发现表明 MCI 中存在病理性的阿尔法减速。
