Giuliani C A, Smith J L
J Neurosci. 1987 Aug;7(8):2537-46.
Adult cats develop spontaneous airstepping (walking motions without ground contact) 4-6 weeks after spinal transection (Giuliani and Smith, 1985). This unique preparation provides an in vivo model for studying the effects of hindlimb deafferentation on stepping behaviors without rostral input to lumbosacral segments. The primary purpose of this study was to characterize airstepping and, to a lesser extent, bipedal treadmill locomotion in chronic spinal cats after deafferentation. Five cats were spinalized at T12, and EMG electrodes were implanted in selected knee and ankle muscles. After spontaneous airstepping developed, one hindlimb was deafferented extensively. Movements of both hindlimbs were depressed following unilateral deafferentation. By the third week, spontaneous airstepping recovered in the normal hindlimb (N-Limb), but in the deafferented limb (D-Limb) airstepping was not spontaneous during the 3-4 months of testing. By the seventh week, bilateral airstepping was facilitated by tonic exteroceptive simulation (tail-pinch). During bouts of bilateral airstepping, assessed during the third month of deafferentation, D-Limb airstep cycles were characterized by erratic rhythm. Further, cycle periods and extensor burst durations were prolonged, but flexor burst durations were unmodified. In contrast, N-Limb cycles were rhythmic and of normal duration, but extensor burst durations were short and unrelated to cycle periods. Interlimb coordination was markedly unstable, showing only brief periods of alternating steps. When erratic bilateral airstepping was accompanied by micturition, rhythmic and alternate stepping emerged, with normalized intralimb synergies. During hindlimb treadmill locomotion, tested in 2 cats, the N-Limb took weight-bearing steps and followed changes in the belt speed. The D-Limb, however, stepped erratically, making contact on the dorsum of the paw; consistent bouts by bilateral stepping were not obtained. Lumbosacral afference of some type, either from the hindlimb or from regions remote from the limb, such as the bladder, appears to be essential for stabilizing the coupling between hindlimb generators for stable interlimb coordination. Future modeling of interlimb coordination should consider the role of afference.
成年猫在脊髓横断后4 - 6周会出现自发空中踏步（无地面接触的行走动作）（朱利亚尼和史密斯，1985年）。这种独特的制备方法提供了一种体内模型，用于研究后肢去传入对踏步行为的影响，且无需向腰骶段提供头端输入。本研究的主要目的是描述慢性脊髓损伤猫在去传入后的空中踏步情况，并在较小程度上描述双足跑步机行走情况。五只猫在T12水平进行脊髓横断，并将肌电图电极植入选定的膝关节和踝关节肌肉。自发空中踏步出现后，对一侧后肢进行广泛去传入处理。单侧去传入后，双侧后肢的运动均受到抑制。到第三周时，正常后肢（N - 肢）的自发空中踏步恢复，但在去传入肢体（D - 肢）中，在3 - 4个月的测试期间空中踏步并非自发产生。到第七周时，通过持续性外感受性刺激（捏尾巴）促进了双侧空中踏步。在去传入第三个月评估的双侧空中踏步发作期间，D - 肢空中踏步周期的特点是节律不稳定。此外，周期时长和伸肌爆发持续时间延长，但屈肌爆发持续时间未改变。相比之下，N - 肢周期有节律且时长正常，但伸肌爆发持续时间较短且与周期时长无关。肢体间协调性明显不稳定，仅显示出短暂的交替踏步期。当不稳定的双侧空中踏步伴有排尿时，会出现有节律的交替踏步，且肢体内部协同作用正常化。在对2只猫进行测试的后肢跑步机行走过程中，N - 肢进行负重踏步并跟随皮带速度的变化。然而，D - 肢踏步不稳定，爪子背部着地；未获得持续的双侧踏步发作。某种类型的腰骶传入，无论是来自后肢还是来自远离肢体的区域，如膀胱，似乎对于稳定后肢发生器之间的耦合以实现稳定的肢体间协调至关重要。未来肢体间协调的建模应考虑传入的作用。
