Department of Medicine and Program in Neurosciences, Faculty of Sciences, University of Fribourg, Chemin du Musée 5, 1700 Fribourg, Switzerland.
Brain Struct Funct. 2012 Jan;217(1):63-79. doi: 10.1007/s00429-011-0327-8. Epub 2011 May 20.
Although the arrangement of the corticospinal projection in primates is consistent with a more prominent role of the ipsilateral motor cortex on proximal muscles, rather than on distal muscles involved in manual dexterity, the role played by the primary motor cortex on the control of manual dexterity for the ipsilateral hand remains a matter a debate, either in the normal function or after a lesion. We, therefore, tested the impact of permanent unilateral motor cortex lesion on the manual dexterity of the ipsilateral hand in 11 macaque monkeys, within a time window of 60 days post-lesion. For comparison, unilateral reversible pharmacological inactivation of the motor cortex was produced in an additional monkey. Manual dexterity was assessed quantitatively based on three motor parameters derived from two reach and grasp manual tasks. In contrast to the expected dramatic, complete deficit of manual dexterity of the contralesional hand that persists for several weeks, the impact on the manual dexterity of the ipsilesional hand was generally moderate (but statistically significant) and, when present, lasted less than 20 days. Out of the 11 monkeys, only 3 showed a deficit of the ipsilesional hand for 2 of the 3 motor parameters, and 4 animals had a deficit for only one motor parameter. Four monkeys did not show any deficit. The reversible inactivation experiment yielded results consistent with the permanent lesion data. In conclusion, the primary motor cortex exerts a modest role on ipsilateral manual dexterity, most likely in the form of indirect hand postural control.
尽管灵长类动物的皮质脊髓投射排列与同侧运动皮层对近端肌肉的作用更为突出一致，而不是对手部灵巧性涉及的远端肌肉作用更为突出，但在正常功能或损伤后，初级运动皮层对同侧手手部灵巧性的控制作用仍存在争议。因此，我们在损伤后 60 天的时间窗口内，在 11 只猕猴中测试了永久性单侧运动皮层损伤对同侧手手部灵巧性的影响。为了进行比较，我们还在另一只猕猴中产生了单侧可逆药理学运动皮层失活。手部灵巧性基于源自两种伸手和抓握手动任务的三个运动参数进行定量评估。与预期的对患侧手手部灵巧性的显著、完全缺失相反，这种缺失持续数周，而对健侧手手部灵巧性的影响通常是中度的（但具有统计学意义），并且在存在时持续时间不到 20 天。在 11 只猴子中，只有 3 只猴子的 3 个运动参数中的 2 个出现了健侧手的缺陷，4 只猴子只有 1 个运动参数出现缺陷。4 只猴子没有出现任何缺陷。可逆失活实验的结果与永久性损伤数据一致。总之，初级运动皮层对同侧手部灵巧性的作用较小，可能是以间接手部姿势控制的形式。
