Tacchino Andrea, Saiote Catarina, Brichetto Giampaolo, Bommarito Giulia, Roccatagliata Luca, Cordano Christian, Battaglia Mario A, Mancardi Gian L, Inglese Matilde
Scientific Research Area, Italian MS Foundation (FISM), Genoa, Italy.
Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, United States.
Front Hum Neurosci. 2018 Jan 11;11:628. doi: 10.3389/fnhum.2017.00628. eCollection 2017.
Motor imagery (MI) is defined as mental execution without any actual movement. While healthy adults usually show temporal equivalence, i.e., isochrony, between the mental simulation of an action and its actual performance, neurological disorders are associated with anisochrony. Unlike in patients with stroke and Parkinson disease, only a few studies have investigated differences of MI ability in multiple sclerosis (MS). However, the relationship among disease severity, anisochrony and brain activation patterns during MI has not been investigated yet. Here, we propose to investigate MI in MS patients using fMRI during a behavioral task executed with dominant/non-dominant hand and to evaluate whether anisochrony is associated with disease severity. Thirty-seven right-handed MS patients, 17 with clinically isolated syndrome (CIS) suggestive of MS and 20 with relapsing-remitting MS (RR-MS) and 20 right-handed healthy controls (HC) underwent fMRI during a motor task consisting in the actual or imaged movement of squeezing a foam ball with the dominant and non-dominant hand. The same tasks were performed outside the MRI room to record the number of actual and imagined ball squeezes, and calculate an Index of performance (IP) based on the ratio between actual and imagined movements. IP showed that a progressive loss of ability in simulating actions (i.e., anisochrony) more pronounced for non-dominant hand, was found as function of the disease course. Moreover, anisochrony was associated with activation of occipito-parieto-frontal areas that were more extensive at the early stages of the disease, probably in order to counteract the changes due to MS. However, the neural engagement of compensatory brain areas becomes more difficult with more challenging tasks, i.e., dominant vs. non-dominant hand, with a consequent deficit in behavioral performance. These results show a strict association between MI performance and disease severity, suggesting that, at early stages of the disease, anisochrony in MI could be considered as surrogate behavioral marker of MS severity.
运动想象（MI）被定义为没有任何实际动作的心理执行过程。虽然健康成年人通常在动作的心理模拟与其实际执行之间表现出时间等效性，即等时性，但神经障碍与非等时性相关。与中风和帕金森病患者不同，只有少数研究调查了多发性硬化症（MS）患者运动想象能力的差异。然而，疾病严重程度、非等时性和运动想象期间大脑激活模式之间的关系尚未得到研究。在此，我们建议在使用优势手/非优势手执行行为任务期间，通过功能磁共振成像（fMRI）对MS患者的运动想象进行研究，并评估非等时性是否与疾病严重程度相关。37名右利手MS患者、17名临床孤立综合征（CIS）提示为MS的患者和20名复发缓解型MS（RR-MS）患者以及20名右利手健康对照（HC）在一项运动任务期间接受了fMRI检查，该任务包括用优势手和非优势手实际或想象挤压一个泡沫球的动作。在MRI室之外执行相同任务以记录实际和想象的球挤压次数，并根据实际和想象动作之间的比率计算表现指数（IP）。IP显示，随着病程进展，可以发现非优势手在模拟动作方面（即非等时性）的能力逐渐丧失更为明显。此外，非等时性与枕顶叶前部区域的激活有关，这些区域在疾病早期更为广泛，可能是为了抵消MS引起的变化。然而，随着任务难度增加，即优势手与非优势手的对比，代偿性脑区的神经参与变得更加困难，从而导致行为表现出现缺陷。这些结果表明运动想象表现与疾病严重程度之间存在紧密关联，这表明在疾病早期，运动想象中的非等时性可被视为MS严重程度的替代行为标志物。
