Darling Warren G, Pizzimenti Marc A, Morecraft Robert J
Department of Health and Human Physiology, Motor Control Laboratories, The University of Iowa, Iowa City, Iowa 52242, USA.
J Integr Neurosci. 2011 Sep;10(3):353-84. doi: 10.1142/S0219635211002737.
This review discusses selected classical works and contemporary research on recovery of contralesional fine hand motor function following lesions to motor areas of the cerebral cortex in non-human primates. Findings from both the classical literature and contemporary studies show that lesions of cortical motor areas induce paresis initially, but are followed by remarkable recovery of fine hand/digit motor function that depends on lesion size and post-lesion training. Indeed, in recent work where considerable quantification of fine digit function associated with grasping and manipulating small objects has been observed, very favorable recovery is possible with minimal forced use of the contralesional limb. Studies of the mechanisms underlying recovery have shown that following small lesions of the digit areas of primary motor cortex (M1), there is expansion of the digit motor representations into areas of M1 that did not produce digit movements prior to the lesion. However, after larger lesions involving the elbow, wrist and digit areas of M1, no such expansion of the motor representation was observed, suggesting that recovery was due to other cortical or subcortical areas taking over control of hand/digit movements. Recently, we showed that one possible mechanism of recovery after lesion to the arm areas of M1 and lateral premotor cortex is enhancement of corticospinal projections from the medially located supplementary motor area (M2) to spinal cord laminae containing neurons which have lost substantial input from the lateral motor areas and play a critical role in reaching and digit movements. Because human stroke and brain injury patients show variable, and usually poorer, recovery of hand motor function than that of nonhuman primates after motor cortex damage, we conclude with a discussion of implications of this work for further experimentation to improve recovery of hand function in human stroke patients.
本综述讨论了关于非人类灵长类动物大脑皮质运动区损伤后对侧精细手部运动功能恢复的一些经典著作和当代研究。经典文献和当代研究的结果均表明,皮质运动区损伤最初会导致轻瘫,但随后精细手部/手指运动功能会有显著恢复,这种恢复取决于损伤大小和损伤后的训练。事实上,在最近的研究中,对与抓取和操作小物体相关的精细手指功能进行了大量量化观察,发现通过对损伤对侧肢体进行最小限度的强制使用,就有可能实现非常良好的恢复。对恢复机制的研究表明,在初级运动皮层(M1)手指区域发生小损伤后,手指运动表征会扩展到损伤前不产生手指运动的M1区域。然而,在涉及M1的肘部、腕部和手指区域的较大损伤后,未观察到运动表征的这种扩展,这表明恢复是由于其他皮质或皮质下区域接管了对手部/手指运动的控制。最近,我们发现,M1和外侧运动前皮层手臂区域损伤后恢复的一种可能机制是,内侧的辅助运动区(M2)向脊髓板层的皮质脊髓投射增强,这些脊髓板层含有一些神经元,它们失去了来自外侧运动区的大量输入,但在伸手和手指运动中起关键作用。由于人类中风和脑损伤患者在运动皮层损伤后手部运动功能的恢复情况各不相同,而且通常比非人类灵长类动物差,因此我们在结尾讨论了这项工作对进一步实验的意义,以改善人类中风患者手部功能的恢复。