Centre for Neuroscience, University of Alberta, Edmonton, Alberta, Canada.
J Neurophysiol. 2012 Dec;108(11):3034-42. doi: 10.1152/jn.00013.2012. Epub 2012 Sep 12.
Electrical stimulation of the lateral gastrocnemius-soleus (LGS) nerve at group I afferent strength leads to adaptations in the amplitude and timing of extensor muscle activity during walking in the decerebrate cat. Such afferent feedback in the stance leg might result from a delay in stance onset of the opposite leg. Concomitant adaptations in hip abductor and adductor activity would then be expected to maintain lateral stability and balance until the opposite leg is able to support the body. As many hip abductors and adductors are also hip extensors, we hypothesized that stimulation of the LGS nerve at group I afferent strength would produce increased activation and prolonged burst duration in hip abductor and adductor muscles in the premammillary decerebrate walking cat. LGS nerve stimulation during the extensor phase of the locomotor cycle consistently increased burst amplitude of the gluteus medius and adductor femoris muscles, but not pectineus or gracilis. In addition, LGS stimulation prolonged the burst duration of both gluteus medius and adductor femoris. Unexpectedly, long-duration LGS stimulus trains resulted in two distinct outcomes on the hip abductor and adductor bursting pattern: 1) a change of burst duration and timing similar to medial gastrocnemius; or 2) to continue rhythmically bursting uninterrupted. These results indicate that activation of muscle afferents from ankle extensors contributes to the regulation of activity of some hip abductor and adductor muscles, but not all. These results have implications for understanding the neural control of stability during locomotion, as well as the organization of spinal locomotor networks.
电刺激外侧腓肠肌-比目鱼肌(LGS)神经的 I 类传入纤维强度,会导致去大脑猫行走时伸肌活动的幅度和时间发生适应性变化。这种支撑腿的传入反馈可能是由于对侧腿支撑起始延迟所致。然后,预计髋关节外展肌和内收肌的协同适应将维持侧向稳定性和平衡,直到对侧腿能够支撑身体。由于许多髋关节外展肌和内收肌也是髋关节伸肌,我们假设,以 I 类传入纤维强度刺激 LGS 神经,会导致去大脑行走猫的前乳突区的髋关节外展肌和内收肌的激活增加和爆发持续时间延长。在运动周期的伸肌阶段进行 LGS 神经刺激, consistently increased burst amplitude (一致增加爆发幅度) of the gluteus medius and adductor femoris muscles(臀中肌和股内收肌),但不包括 pectineus 或 gracilis(耻骨肌或髂腰肌)。此外,LGS 刺激延长了臀中肌和股内收肌的爆发持续时间。出乎意料的是,长时间的 LGS 刺激会导致髋关节外展肌和内收肌爆发模式出现两种截然不同的结果:1)爆发持续时间和时机的变化类似于内侧腓肠肌;2)继续无中断的节律性爆发。这些结果表明,来自踝关节伸肌的肌肉传入纤维的激活有助于调节一些髋关节外展肌和内收肌的活动,但不是全部。这些结果对于理解运动过程中的稳定性神经控制以及脊髓运动网络的组织具有重要意义。