Ferreri Florinda, Vecchio Fabrizio, Guerra Andrea, Miraglia Francesca, Ponzo David, Vollero Luca, Iannello Giulio, Maatta Sara, Mervaala Esa, Rossini Paolo Maria, Di Lazzaro Vincenzo
Unit of Neurology, Neurophysiology, Neurobiology, Department of Medicine, Università Campus Bio-Medico di Roma, via Álvaro del Portillo 21, 00128 Rome, Italy; Department of Clinical Neurophysiology, Kuopio University Hospital, University of Eastern Finland, Kuopio, Finland.
Brain Connectivity Laboratory, IRCCS San Raffaele Pisana, Rome, Italy.
Neurosci Lett. 2017 Apr 24;647:141-146. doi: 10.1016/j.neulet.2017.03.021. Epub 2017 Mar 18.
It was recently demonstrated that the characteristics of EEG rhythms preceding a transcranial magnetic stimulation (TMS) of the motor cortex (M1) influence the motor-evoked potential (MEP) amplitude with a peculiar pattern, thus reflecting the M1 functional state. As physiological aging is related to a decrease in motor performance and changes in excitability and connectivity strength within cerebral sensorimotor circuits, we aimed to explore whether aging affects EEG-MEP interactions. Using MRI-navigated TMS and multichannel EEG, we compared the EEG-MEP interactions observed in healthy aged subjects with those observed in young volunteers. We divided the MEPs amplitude into two different subgroups consisting of "high" and "low" MEPs, based on the 50th percentile of their amplitude distribution. Then we analysed the characteristics of the pre-stimulus EEG from M1 and correlated areas separately for the "high" and "low" MEPs, comparing the two conditions. In both young and old subjects, significantly larger MEPs were evoked when the stimulated M1 was coupled in the beta-2 band with the homolateral prefrontal cortex. Conversely, only in young participants was the MEP size modulated when the M1 and homolateral parieto-occipital cortices were coupled in the delta band. The elderly didn't show this kind of pattern. Importantly, this coupling was significantly higher in elderly brains than in young brains, both for high and low MEPs. Our results suggest an age-related significant influence of time-varying coupling of spatially patterned EEG rhythms on motor cortex excitability in response to TMS.
最近有研究表明，运动皮层（M1）经颅磁刺激（TMS）之前的脑电图（EEG）节律特征会以一种特殊模式影响运动诱发电位（MEP）的幅度，从而反映M1的功能状态。由于生理衰老与运动表现下降以及大脑感觉运动回路内兴奋性和连接强度的变化有关，我们旨在探讨衰老是否会影响EEG-MEP相互作用。我们使用MRI导航的TMS和多通道EEG，比较了健康老年受试者和年轻志愿者中观察到的EEG-MEP相互作用。我们根据MEP幅度分布的第50百分位数，将MEP幅度分为由“高”和“低”MEP组成的两个不同亚组。然后，我们分别分析了“高”和“低”MEP刺激前来自M1和相关区域的EEG特征，并比较了这两种情况。在年轻和老年受试者中，当受刺激的M1在β-2频段与同侧前额叶皮层耦合时，诱发的MEP明显更大。相反，只有在年轻参与者中，当M1和同侧顶枕叶皮层在δ频段耦合时，MEP大小才会受到调制。老年人没有表现出这种模式。重要的是，无论高MEP还是低MEP，这种耦合在老年大脑中都比年轻大脑中显著更高。我们的结果表明，随时间变化的空间模式EEG节律耦合对TMS反应中的运动皮层兴奋性具有与年龄相关的显著影响。
