Contribution of the motor cortex to the structure and the timing of hindlimb locomotion in the cat: A microstimulation study
Contribution of the motor cortex to the structure and the timing of hindlimb locomotion in the cat: A microstimulation study
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DOI：
10.1152/jn.01245.2004
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发表时间：
2005-07-01
影响因子：
2.5
通讯作者：
Drew, T
中科院分区：
文献类型：
--
作者：
Bretzner, F;Drew, T
我们使用微刺激检查的贡献的运动皮层的结构和时间的后肢步骤周期在运动过程中的完整的猫。刺激施加到后肢表示的运动皮层在34个网站在3只猫使用标准的玻璃绝缘微电极（16个网站在1只猫）或长期植入的微丝电极（18个网站在2只猫）。猫在休息时以阈上强度刺激，在大多数部位（21/34，62%）产生多关节运动，但在其他13/34（38%）部位诱发的反应仅限于单个关节，通常为踝关节。在运动过程中的刺激通常比在休息时的相同刺激引起更大的反应，并经常激活额外的肌肉。刺激在所有34个网站诱发相位依赖性反应，其中刺激在摆动产生短暂的活动增加屈肌，而在立场刺激产生短暂的活动减少伸肌。刺激与长（200毫秒）列车的刺激，在摆动产生的活动水平和持续时间的屈肌，而不产生周期持续时间的变化。相反，在站立时的刺激减少了伸肌活动的持续时间，并启动了一个新的和过早的摆动期，重置步骤周期。刺激这三只猫中的两只以及另外两只猫的锥体束产生了类似的效果。结果表明，运动皮层能够影响后肢活动在运动过程中以类似的方式看到的前肢。
We used microstimulation to examine the contribution of the motor cortex to the structure and timing of the hindlimb step cycle during locomotion in the intact cat. Stimulation was applied to the hindlimb representation of the motor cortex in 34 sites in three cats using either standard glass-insulated microelectrodes (16 sites in 1 cat) or chronically implanted microwire electrodes (18 sites in 2 cats). Stimulation at just suprathreshold intensities with the cat at rest produced multijoint movements at a majority of sites (21/34, 62%) but evoked responses restricted to a single joint, normally the ankle, at the other 13/34 (38%) sites. Stimulation during locomotion generally evoked larger responses than the same stimulation at rest and frequently activated additional muscles. Stimulation at all 34 sites evoked phase-dependent responses in which stimulation in swing produced transient increases in activity in flexor muscles while stimulation during stance produced transient decreases in activity in extensors. Stimulation with long (200 ms) trains of stimuli in swing produced an increased level of activity and duration of flexor muscles without producing changes in cycle duration. In contrast, stimulation during stance decreased the duration of the extensor muscle activity and initiated a new and premature period of swing, resetting the step cycle. Stimulation of the pyramidal tract in two of these three cats as well as in two additional ones produced similar effects. The results show that the motor cortex is capable of influencing hindlimb activity during locomotion in a similar manner to that seen for the forelimb.