Coq Jacques-Olivier, Barr Ann E, Strata Fabrizio, Russier Michael, Kietrys David M, Merzenich Michael M, Byl Nancy N, Barbe Mary F
UMR 6149 Neurobiologie Intégrative et Adaptative, CNRS-Aix-Marseille Université, Pôle 3C, Case B, 3 Place Victor Hugo, 13331, Marseille Cedex 03, France.
Exp Neurol. 2009 Dec;220(2):234-45. doi: 10.1016/j.expneurol.2009.08.008. Epub 2009 Aug 15.
Repetitive motion disorders, such as carpal tunnel syndrome and focal hand dystonia, can be associated with tasks that require prolonged, repetitive behaviors. Previous studies using animal models of repetitive motion have correlated cortical neuroplastic changes or peripheral tissue inflammation with fine motor performance. However, the possibility that both peripheral and central mechanisms coexist with altered motor performance has not been studied. In this study, we investigated the relationship between motor behavior changes associated with repetitive behaviors and both peripheral tissue inflammation and cortical neuroplasticity. A rat model of reaching and grasping involving moderate repetitive reaching with negligible force (MRNF) was used. Rats performed the MRNF task for 2 h/day, 3 days/week for 8 weeks. Reach performance was monitored by measuring reach rate/success, daily exposure, reach movement reversals/patterns, reach/grasp phase times, grip strength and grooming function. With cumulative task exposure, reach performance, grip strength and agility declined while an inefficient food retrieval pattern increased. In S1 of MRNF rats, a dramatic disorganization of the topographic forepaw representation was observed, including the emergence of large receptive fields located on both the wrist/forearm and forepaw with alterations of neuronal properties. In M1, there was a drastic enlargement of the overall forepaw map area, and of the cortex devoted to digit, arm-digits and elbow-wrist responses. In addition, unusually low current amplitude evoked digit movements. IL-1 beta and TNF-alpha increased in forearm flexor muscles and tendons of MRNF animals. The increases in IL-1 beta and TNF-alpha negatively correlated with grip strength and amount of current needed to evoke forelimb movements. This study provides strong evidence that both peripheral inflammation and cortical neuroplasticity jointly contribute to the development of chronic repetitive motion disorders.
重复性运动障碍，如腕管综合征和局灶性手部肌张力障碍，可能与需要长期重复行为的任务有关。先前使用重复性运动动物模型的研究已将皮质神经可塑性变化或外周组织炎症与精细运动表现相关联。然而，外周和中枢机制与运动表现改变同时存在的可能性尚未得到研究。在本研究中，我们调查了与重复行为相关的运动行为变化与外周组织炎症和皮质神经可塑性之间的关系。使用了一种涉及适度重复伸展且力量可忽略不计（MRNF）的大鼠抓握模型。大鼠每天进行2小时的MRNF任务，每周3天，共8周。通过测量伸展速率/成功率、每日暴露时间、伸展运动反转/模式、伸展/抓握阶段时间、握力和梳理功能来监测伸展表现。随着任务暴露的累积，伸展表现、握力和敏捷性下降，而低效的食物获取模式增加。在MRNF大鼠的初级躯体感觉皮层（S1）中，观察到前爪地形图的显著紊乱，包括在手腕/前臂和前爪上出现大的感受野以及神经元特性的改变。在初级运动皮层（M1）中，前爪总图区域以及专门用于手指、手臂-手指和肘部-手腕反应的皮层区域大幅扩大。此外，诱发手指运动所需的电流幅度异常低。MRNF动物的前臂屈肌和肌腱中白细胞介素-1β（IL-1β）和肿瘤坏死因子-α（TNF-α）增加。IL-1β和TNF-α的增加与握力以及诱发前肢运动所需的电流量呈负相关。本研究提供了有力证据，表明外周炎症和皮质神经可塑性共同促成慢性重复性运动障碍的发展。
