Hernandez P, Elbert K, Droge M H
Department of Biology, Texas Woman's University, Denton 76204.
Exp Brain Res. 1991;85(1):66-74. doi: 10.1007/BF00229987.
The current paper presents our initial efforts to establish an in vitro spinal preparation for investigating locomotor pattern generation in mice. We have characterized the step cycle timing from EMG activity in the gastrocnemius (G) and tibialis anterior (TA) muscles of freely moving intact adult as well as neonatal mice and then compared those data with rhythmic EMG activity in an isolated spinal cord-hindlimb preparation. The motor output during the first four days of life was evaluated in an effort to identify the optimal post-partum period for in vitro locomotor studies. The in vitro pattern generating capabilities of the lumbosacral region were tested in both nonhemisected and hemisected preparations. Spontaneous as well as NMDA evoked in vitro activity in the antagonist set of hindlimb muscles included sequences of: 1) synchronous bursting; 2) mixed synchrony and alternation; and/or 3) irregular alternations. The alternating bursting observed in vitro was more often an alternation of sequences rather than a cycle-to-cycle phasing between G and TA muscles. In summary, while there was evidence of reciprocal inhibition in neonates, the circuitry for cycle-to-cycle alternation between antagonists was found to be labile.
本文展示了我们为建立用于研究小鼠运动模式生成的体外脊髓制备方法所做的初步努力。我们已对自由活动的成年及新生完整小鼠腓肠肌（G）和胫骨前肌（TA）的肌电图（EMG）活动中的步周期时间进行了表征，然后将这些数据与分离的脊髓 - 后肢制备物中的节律性EMG活动进行了比较。为了确定体外运动研究的最佳产后时期，我们评估了出生后前四天的运动输出。在未半切和半切的制备物中测试了腰骶部区域的体外模式生成能力。后肢拮抗肌群中自发的以及NMDA诱发的体外活动包括以下序列：1）同步爆发；2）同步与交替混合；和/或3）不规则交替。体外观察到的交替爆发更常见的是序列的交替，而不是G肌和TA肌之间逐周期的相位变化。总之，虽然有证据表明新生儿存在交互抑制，但发现拮抗肌之间逐周期交替的神经回路不稳定。
