Task-dependent modification of leg motor neuron synaptic input underlying changes in walking direction and walking speed.
Task-dependent modification of leg motor neuron synaptic input underlying changes in walking direction and walking speed.
复制标题
腿部运动神经元突触输入的任务依赖性修改导致步行方向和步行速度的变化。
DOI：
10.1152/jn.00006.2015
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发表时间：
2015
影响因子：
2.5
通讯作者：
A. Büschges
中科院分区：
文献类型：
--
作者：
P. Rosenbaum;J. Schmitz;Joachim Schmidt;A. Büschges
动物不断调整自己的行为，以便在环境中充分发挥作用。在陆地运动中存在多种形式的适应。两个任务是步行方向和步行速度的变化。我们研究了竹节虫运动输出的这两种变化，以了解它们是如何在腿部运动神经元水平上产生的。我们使用了一种半完整的制备方法，在这种方法中我们可以记录行走过程中腿部运动神经元的细胞内活动。在这种单腿准备中，动物的中间腿在踏轮上以垂直平面行走。对腹部或头部的刺激可分别引起固定和其他失活的胸-髋关节有效的前向或后向运动活动。随着行走方向的改变，只有胸-髋-关节运动神经元量角器和牵开器的活动发生改变。量角器在向前行走时从摆动活动切换到后退行走时的站立活动，牵开器从站立活动切换到摆动。这种相位转换是由于相突触输入在步进周期的特定阶段从抑制性到兴奋性的相应变化，反之亦然。除了相位突触输入外，还存在运动神经元的强直性去极化。站立时步伐速度的变化与屈肌运动神经元的活动有显著的相关性，而与向前行走时牵张和抑制运动神经元的活动无显著的相关性。这些结果表明，竹节虫行走系统中的不同任务仅通过改变特定腿部关节运动神经元的突触输入而产生。
Animals modify their behavior constantly to perform adequately in their environment. In terrestrial locomotion many forms of adaptation exist. Two tasks are changes of walking direction and walking speed. We investigated these two changes in motor output in the stick insect Cuniculina impigra to see how they are brought about at the level of leg motor neurons. We used a semi-intact preparation in which we can record intracellularly from leg motor neurons during walking. In this single-leg preparation the middle leg of the animal steps in a vertical plane on a treadwheel. Stimulation of either abdomen or head reliably elicits fictive forward or backward motor activity, respectively, in the fixed and otherwise deafferented thorax-coxa joint. With a change of walking direction only thorax-coxa-joint motor neurons protractor and retractor changed their activity. The protractor switched from swing activity during forward to stance activity during backward walking, and the retractor from stance to swing. This phase switch was due to corresponding change of phasic synaptic inputs from inhibitory to excitatory and vice versa at specific phases of the step cycle. In addition to phasic synaptic input a tonic depolarization of the motor neurons was present. Analysis of changes in stepping velocity during stance showed only a significant correlation to flexor motor neuron activity, but not to that of retractor and depressor motor neurons during forward walking. These results show that different tasks in the stick insect walking system are generated by altering synaptic inputs to specific leg joint motor neurons only.