Department of Physiology, Faculty of Medicine and Health Sciences, UAE University, PO Box 17666, Al Ain, United Arab Emirates.
Curr Alzheimer Res. 2013 Jul;10(6):578-96. doi: 10.2174/15672050113109990133.
Although the brain's ability to change constantly in response to external and internal inputs is now well recognized the mechanisms behind it in normal aging and neurodegeneration are less well understood. To gain a better understanding, transcranial magnetic stimulation (TMS) has been used extensively to characterize non-invasively the cortical neurophysiology of the aging and degenerating brain. Furthermore, there has been a surge of studies examining whether repetitive TMS (rTMS) can be used to improve functional deficits in various conditions including normal aging, Alzheimer's and Parkinson's disease. The results of these studies in normal aging and neurodegeneration have emerged reasonably coherent in delineating the main pathology in spite of considerable technical limitations, omnipresent methodological variability, and extraordinary patient heterogeneity. Nevertheless, comparing and integrating what is known about TMS measurements of cortical excitability and plasticity in disorders that predominantly affect cortical brain structures with disorders that predominantly affect subcortical brain structures may provide better understanding of normal and abnormal brain aging fostering new. The present review provides a TMS perspective of changes in cortical neurophysiology and neurochemistry in normal aging and neurodegeneration by integrating what is revealed in individual TMS measurements of cortical excitability and plasticity in physiological aging, Alzheimer's, Parkinson's, and Huntington's, disease. The paper also reflects on current developments in utilizing TMS as a physiologic biomarker to discriminate physiologic aging from neurodegeneration and its potential as a method of therapeutic intervention.
尽管大脑对外界和内部输入的不断变化的能力现在已经得到了广泛的认可，但其在正常衰老和神经退行性变中的机制却了解得较少。为了更好地理解这一现象，经颅磁刺激（TMS）已被广泛用于非侵入性地描述衰老和退化大脑的皮质神经生理学。此外，已经有大量研究检查重复经颅磁刺激（rTMS）是否可以用于改善各种情况下的功能缺陷，包括正常衰老、阿尔茨海默病和帕金森病。这些研究在正常衰老和神经退行性变中的结果尽管存在相当多的技术限制、普遍存在的方法学可变性和非凡的患者异质性，但在描绘主要病理学方面相当一致。然而，比较和整合已知的关于皮质兴奋性和可塑性的 TMS 测量在主要影响皮质脑结构的疾病与主要影响皮质下脑结构的疾病中的情况，可以更好地理解正常和异常的大脑衰老，促进新的研究。本综述通过整合生理衰老、阿尔茨海默病、帕金森病和亨廷顿病中皮质兴奋性和可塑性的个体 TMS 测量所揭示的内容，从 TMS 的角度提供了正常衰老和神经退行性变中皮质神经生理学和神经化学变化的观点。本文还反映了利用 TMS 作为生理生物标志物来区分生理衰老和神经退行性变的当前发展及其作为治疗干预方法的潜力。
