de Guzman C P, Roy R R, Hodgson J A, Edgerton V R
Neuromuscular Research Laboratory, Department of Kinesiology, Los Angeles, CA 90024.
Brain Res. 1991 Aug 2;555(2):202-14. doi: 10.1016/0006-8993(91)90343-t.
The coordination of the motor pools of two ankle plantar-flexor, i.e. the soleus (Sol) and medial gastrocnemius (MG), and an ankle dorsiflexor, i.e. the tibialis anterior (TA) was quantified by comparing the EMG amplitude relationships in muscle pairs in normal and trained adult spinalized cats during treadmill walking across a range of relatively slow speeds (0.1 to 1.0 m/s). The effects of increased tactile stimulation or loading on locomotor performance were also studied in the spinal cats. Joint probability density distributions in the spinalized cats showed a low level of MG activation relative to Sol which did not change as speed increased. In general, the coordination between Sol and MG was similar in normal and spinal cats. However, towards the final phase of the extensor burst, the MG EMG amplitude decayed prematurely in spinal cats, particularly at higher speeds. Preferential elevation of MG relative to Sol activity was seen as a result of tactile stimulation. An elevated load resulted in a higher level of MG activation relative to Sol, prolonged MG activity at the end of the extensor burst, and the reduction in the clonic pattern of EMG typical of spinal cats. Spinalized cats showed an increased incidence of Sol-TA coactivation, especially at the higher speeds, due in part to the tonic activity in the TA. However, the overall reciprocal relationship between these antagonists was maintained. This reciprocity was preserved, but the high level of coactivation was unaffected by tactile stimulation. An elevated load, however, resulted in less Sol-TA coactivation. These results suggest that the coordination between synergists (Sol-MG) and between antagonists (Sol-TA and MG-TA), as well as the level of activation are modulated in the adult spinal cat similar to that observed in the normal cat. Further, there are specific types of proprioceptive-cutaneous information that can affect selected phases of the step cycle such that full weight-supporting stepping is significantly improved.
通过比较正常和受过训练的成年脊髓损伤猫在跑步机上以一系列相对较慢速度（0.1至1.0米/秒）行走时肌肉对中的肌电图（EMG）幅度关系，对两个踝关节跖屈肌即比目鱼肌（Sol）和内侧腓肠肌（MG）以及一个踝关节背屈肌即胫骨前肌（TA）的运动神经元池的协调性进行了量化。还研究了脊髓损伤猫中增加触觉刺激或负荷对运动表现的影响。脊髓损伤猫的联合概率密度分布显示，相对于Sol，MG的激活水平较低，且不会随着速度增加而改变。一般来说，正常猫和脊髓损伤猫中Sol和MG之间的协调性相似。然而，在伸肌爆发的最后阶段，脊髓损伤猫的MG肌电图幅度过早衰减，尤其是在较高速度时。触觉刺激导致MG相对于Sol活动的优先升高。负荷增加导致相对于Sol的MG激活水平更高，伸肌爆发结束时MG活动延长，以及脊髓损伤猫典型的肌电图阵挛模式减少。脊髓损伤猫中Sol-TA共激活的发生率增加，尤其是在较高速度时，部分原因是TA中的紧张性活动。然而，这些拮抗肌之间的整体相互关系得以维持。这种相互关系得以保留，但高水平的共激活不受触觉刺激影响。然而，负荷增加导致Sol-TA共激活减少。这些结果表明，成年脊髓损伤猫中协同肌（Sol-MG）之间以及拮抗肌（Sol-TA和MG-TA）之间的协调性以及激活水平与正常猫中观察到的情况类似受到调节。此外，存在特定类型的本体感觉 - 皮肤信息可以影响步周期的选定阶段，从而显著改善完全负重行走。
