Armand J, Kably B
Centre National de la Recherche Scientifique, Laboratoire de Neurobiologie, Marseilles, France.
Exp Brain Res. 1993;93(1):73-88. doi: 10.1007/BF00227782.
Forelimb movements and motor skills were studied in adult cats in order to determine the effect of brain damage inflicted at different postnatal ages. The unilateral lesion included the cortical areas from which the pyramidal tract originates in cat: areas 4 and 6 corresponding to the motor cortex; areas 3, 2 and 1 corresponding to the primary somatosensory cortex; and part of area 2 prae-insularis corresponding to the secondary somatosensory cortex. Forelimb performance of a food-retrieving task requiring proximal as well as distal muscles was assessed by comparing the limb contralateral to the damaged hemisphere (affected limb) with the limb contralateral to the intact hemisphere (non-affected limb) that appeared to perform the task as well as both limbs of control animals. In simple task-related movements, all operated animals were rapidly able to achieve the goal with the affected limb, whatever the age at lesion. In complex tasks, the ability to achieve the goal with the affected limb decreased with increasing age at lesion. Recovery of distal skills, i.e. grasping and wrist rotation, did not occur in animals operated on after the 23rd postnatal day (PND), and recovery of proximal skills, i.e. amplitude and precision of the reaching movement, did not occur in animals operated on after the 45th PND. The critical time for the recovery of distal skills lies somewhere between the 23rd and 30th PND, whereas for the recovery of proximal skills it lies somewhere between the 45th and 60th PND. These critical dates for the recovery of motor skills support the Kennard doctrine. Different critical times for proximal and distal skills may be explained in terms of different stages of sensorimotor development in kitten. It is hypothesised that recovery only occurs if brain damage is inflicted before maturation of the nervous system underlying a given motor skill.
为了确定不同出生后年龄造成的脑损伤的影响，对成年猫的前肢运动和运动技能进行了研究。单侧损伤包括猫的锥体束起源的皮质区域：对应于运动皮层的4区和6区；对应于初级体感皮层的3区、2区和1区；以及对应于次级体感皮层的岛前2区的一部分。通过将受损半球对侧的肢体（受影响肢体）与完整半球对侧的肢体（未受影响肢体）进行比较，评估了一项需要近端和远端肌肉的取食任务的前肢表现，未受影响肢体似乎能像对照动物的双肢一样完成任务。在简单的与任务相关的运动中，无论损伤时的年龄如何，所有接受手术的动物都能迅速用受影响的肢体实现目标。在复杂任务中，用受影响肢体实现目标的能力随着损伤时年龄的增加而下降。出生后第23天（PND）后接受手术的动物未出现远端技能（即抓握和手腕旋转）的恢复，出生后第45天PND后接受手术的动物未出现近端技能（即伸手动作的幅度和精度）的恢复。远端技能恢复的关键时间在第23天至第30天PND之间，而近端技能恢复的关键时间在第45天至第60天PND之间。这些运动技能恢复的关键日期支持肯纳德学说。近端和远端技能的不同关键时间可以根据小猫感觉运动发育的不同阶段来解释。据推测，只有在给定运动技能的神经系统成熟之前造成脑损伤，恢复才会发生。
