Informatics Research Centre, Universidad Central "Marta Abreu" de Las Villas, carreta a Camajuani km 81/2, Santa Clara, Villa Clara, Cuba.
Centre for the Research and Rehabilitation of Hereditary Ataxias, Calle Libertad No. 26, Holguin, Cuba.
Cerebellum. 2020 Oct;19(5):665-671. doi: 10.1007/s12311-020-01149-z.
Corticomuscular and intermuscular coherence (CMC, IMC) reflect connectivity between neuronal activity in the motor cortex measured by electroencephalography (EEG) and muscular activity measured by electromyography (EMG), or between activity in different muscles, respectively. There is an ongoing debate on the appropriateness of EMG rectification prior to coherence estimation. This work examines the effects of EMG rectification in CMC and IMC estimation in 20 spinocerebellar ataxia type 2 (SCA2) patients, 16 prodromal SCA2 gene mutation carriers, and 26 healthy controls during a repetitive upper or lower limb motor task. Coherence estimations were performed using the non-rectified raw EMG signal vs. the rectified EMG signal. EMG rectification decreases the level of significance of lower beta-frequency band CMC and IMC values in SCA2 patients and prodromal SCA2 mutation carriers vs. healthy controls, and also results in overall lower coherence values. EMG rectification is detrimental for beta-frequency band CMC and IMC estimation. One likely reason for this effect is distortion of coherence estimation in high-frequency signals, where the level of amplitude cancelation is high.
皮质肌和肌间相干性（CMC、IMC）分别反映了脑电图（EEG）测量的运动皮层神经元活动与肌电图（EMG）测量的肌肉活动之间，或不同肌肉之间的连通性。目前，关于在相干性估计之前对 EMG 进行整流是否合适存在争议。这项工作检查了在重复上肢或下肢运动任务期间，20 名脊髓小脑共济失调 2 型（SCA2）患者、16 名 SCA2 基因突变携带者和 26 名健康对照者中，EMG 整流对 CMC 和 IMC 估计的影响。相干性估计是使用非整流原始 EMG 信号与整流 EMG 信号进行的。EMG 整流降低了 SCA2 患者和前驱 SCA2 基因突变携带者与健康对照组相比，较低β频带 CMC 和 IMC 值的显著性水平，也导致整体相干值降低。EMG 整流不利于β频带 CMC 和 IMC 的估计。这种影响的一个可能原因是高频信号中的相干性估计失真，其中幅度抵消的程度很高。
