McKenna J E, Whishaw I Q
Department of Psychology and Neuroscience, University of Lethbridge, Alberta, Canada, T1K 3M4.
J Neurosci. 1999 Mar 1;19(5):1885-94. doi: 10.1523/JNEUROSCI.19-05-01885.1999.
Each of the dorsal columns of the rat spinal cord conveys primary sensory information, by way of the medullary dorsal column nucleus, to the ventrobasal thalamus on the contralateral side; thus the dorsal columns are an important source of neural input to the sensorimotor cortex. Damage to the dorsal columns causes impairments in synergistic proximal or whole-body movements in cats and distal limb impairments in primates, particularly in multiarticulated finger movements and tactile foviation while handling objects, but the behavioral effects of afferent fiber lesions in the dorsal columns of rodents have not been described. Female Long-Evans rats were trained to reach with a forelimb for food pellets and subsequently received lesions of the dorsomedial spinal cord at the C2 level, ipsilateral to their preferred limb. Reaching success completely recovered within a few days of dorsal column lesion. Nevertheless, a detailed analysis of high-speed video recordings revealed that rotatory limb movements (aiming, pronation, supination, etc.) were irreversibly impaired. Compensation was achieved with whole-body and alternate limb movements. These results indicate the following: (1) in the absence of the dorsal columns, other sensorimotor pathways support endpoint success in reaching; (2) sensory input conveyed by the dorsal columns is important for both proximal and distal limb movements used for skilled reaching; and (3) detailed behavioral analyses in addition to endpoint measures are necessary to completely describe the effects of dorsal column lesions.
大鼠脊髓的每个背柱都通过延髓背柱核，将初级感觉信息传递至对侧的腹侧基底丘脑；因此，背柱是感觉运动皮层神经输入的重要来源。背柱损伤会导致猫的协同近端或全身运动受损，以及灵长类动物的远端肢体功能障碍，尤其是在操作物体时的多关节手指运动和触觉注视方面，但尚未描述啮齿动物背柱传入纤维损伤的行为影响。对雌性Long-Evans大鼠进行训练，使其用前肢够取食物颗粒，随后在其偏好肢体同侧的C2水平对脊髓背内侧进行损伤。背柱损伤后几天内，够取成功率完全恢复。然而，对高速视频记录的详细分析表明，旋转肢体运动（瞄准、旋前、旋后等）受到了不可逆的损害。通过全身和交替肢体运动实现了补偿。这些结果表明：（1）在没有背柱的情况下，其他感觉运动通路支持够取动作的终点成功；（2）背柱传递的感觉输入对于用于熟练够取的近端和远端肢体运动都很重要；（3）除了终点测量外，还需要进行详细的行为分析，以全面描述背柱损伤的影响。
