Shimamura M, Tanaka I, Fuwa T
Department of Neurophysiology, Tokyo Metropolitan Institute for Neurosciences, Japan.
Neurosci Res. 1990 Feb;7(4):358-68. doi: 10.1016/0168-0102(90)90010-c.
To analyze changes in the excitability of both the spinal cord and brainstem in thalamic cats stepping on a moving treadmill, we examined the cutaneous propriospinal (PSR) and spino-bulbo-spinal (SBS) reflex responses in 20 adult cats. Tracheal cannulation, spinal transection at the T10 segment, and decerebration at the stereotaxic A12 level were performed under ether anesthesia. Immediately after decerebration, the ether was withdrawn. The head was fixed in a stereotaxic device, the T2 spinal process clamped to a metal frame, and the lumbar region suspended by a hammock, with bilateral forelimb contact on the floor of a treadmill. Electrical stimulation was applied to the superficial radial nerve with a cuff electrode, and two reflex responses (PSR and SBS) were recorded from the biceps brachii muscle in the same forelimb. Shortly before the appearance of forelimb stepping, both PSR and SBS reflex responses were elevated in amplitude. During forelimb stepping, the amplitudes of PSR and SBS reflex responses fluctuated depending on the phase of the step cycle. The PSR response was enhanced in the early phase of the swing, whereas the SBS response was elevated during a wider period from the beginning of the stance to the middle of the swing. The SBS response was completely absent in the late phase of the swing. This period corresponded to the transfer from flexion to extension and the appearance of the EMG of the triceps brachii muscle of the same forelimb. The fluctuation of the SBS response during stepping may be produced at the brainstem level, and not the spinal cord level, because the PSR response was enhanced only during narrow periods. The generation of locomotion thus seems to result in an enhancement of excitability of reflex pathways in the spinal cord and particularly in the brainstem.
为了分析丘脑猫在移动跑步机上行走时脊髓和脑干兴奋性的变化，我们检测了20只成年猫的皮肤固有脊髓（PSR）和脊髓 - 延髓 - 脊髓（SBS）反射反应。在乙醚麻醉下进行气管插管、T10节段脊髓横断以及在立体定位A12水平进行去大脑手术。去大脑手术完成后立即停止使用乙醚。将头部固定在立体定位装置中，将T2棘突夹在金属框架上，腰部区域用吊床悬吊，双侧前肢接触跑步机地面。用袖带电极对桡神经浅支进行电刺激，并在同一前肢的肱二头肌记录两种反射反应（PSR和SBS）。在前肢开始迈步前不久，PSR和SBS反射反应的幅度均升高。在前肢迈步过程中，PSR和SBS反射反应的幅度根据步周期的阶段而波动。PSR反应在摆动早期增强，而SBS反应在从站立开始到摆动中期的更广泛时间段内升高。SBS反应在摆动后期完全消失。这个时期对应于同一前肢从屈曲到伸展的转变以及肱三头肌肌电图的出现。迈步过程中SBS反应的波动可能发生在脑干水平，而非脊髓水平，因为PSR反应仅在狭窄时间段内增强。因此，运动的产生似乎导致脊髓尤其是脑干中反射通路兴奋性的增强。
