Step, swim, and scratch motor patterns in the turtle
Step, swim, and scratch motor patterns in the turtle
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DOI：
10.1152/jn.2000.84.5.2181
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发表时间：
2000-11-01
影响因子：
2.5
通讯作者：
Stein, PSG
中科院分区：
文献类型：
--
作者：
Earhart, GM;Stein, PSG
海龟产生各种协调的后肢运动，包括不同形式的运动和抓挠。完整的海龟会向前迈步、向前游动和向后划水。在脊髓横断后，通过对壳的机械刺激可以诱发吻侧、囊袋和尾侧划痕。这六种行为的运动学和运动模式的比较提供了关于其产生的神经机制的见解。所有六种行为的特征都是交替的髋关节屈曲和伸展，以及在此期间对基底施加力的事件。髋关节屈曲或伸展运动所占的周期部分因行为而异。髋关节伸展占据了一半以上的周期在前进一步和尾部抓。该周期分为大约一半髋关节屈曲和一半髋关节伸展，用于向前游泳，背桨和喙部抓挠。髋关节屈曲在囊袋划痕中占据了一半以上的周期。游泳和抓挠形式的曲线，新月形的脚趾轨迹和单关节膝伸肌活动在每个周期中的一个单一的爆发。向前一步有一个线性的脚趾轨迹和两个爆发的膝盖伸肌活动在每个周期，一个在摆动和一个在立场。单关节膝伸肌起始的时间相似：向前游泳、吻侧抓挠和向前迈步的摆动相爆发;袋状抓挠和向前迈步的站立相爆发;以及背桨和尾侧抓挠。肌肉活动的振幅在六种行为之间变化;高振幅的活动与对基底施加力的事件相关。这些时间的力量施加：在向前一步的立场相，在向前游泳和backpaddle的powerstroke，和摩擦的肢体对壳的划痕形式。所研究的六种行为代表了一系列参数值，如髋关节屈曲至髋关节伸展的相对持续时间、膝关节伸肌定相和肌电图（EMG）振幅所证明的。这一系列的行为可以通过从一个共同的池中组装不同的神经元组合来产生，所有六种行为都可能共享一些基本的电路。共享电路的程度可以在具有相似时序的行为之间更大，例如，背部划水和尾部抓挠
The turtle generates a variety of coordinated hindlimb movements, including different forms of locomotion and scratching. The intact turtle produces forward step, forward swim, and backpaddle. Following spinal cord transection, rostral, pocket, and caudal scratches can be evoked by mechanical stimulation of the shell. Comparisons of the kinematics and motor patterns of these six behaviors provide insights regarding neuronal mechanisms underlying their production. All six behaviors were characterized by alternating hip flexion and extension and by an event during which force was exerted against a substrate. The portion of the cycle occupied by hip flexion or extension movement varied across behaviors. Hip extension occupied well over half the cycle period in the forward step and the caudal scratch. The cycle was split into approximately half hip flexion and half hip extension for the forward swim, the backpaddle, and the rostral scratch. Hip flexion occupied over half the cycle in the pocket scratch. The swim and scratch forms had curvilinear, crescent-shaped toe trajectories and a single burst of monoarticular knee extensor activity during each cycle. The forward step had a linear toe trajectory and two bursts of knee extensor activity during each cycle, one during swing and one during stance. Timing of monoarticular knee extensor onset was similar for: the forward swim, the rostral scratch, and the swing phase burst of forward step; the pocket scratch and the stance phase burst of forward step; and the backpaddle and the caudal scratch. Amplitudes of muscle activity varied among the six behaviors; high amplitudes of activity were associated with events during which force was exerted against a substrate. These times of force exertion were: stance phase in the forward step, powerstroke in the forward swim and the backpaddle, and rubs of the limb against the shell in the scratch forms. The six behaviors studied represent a range of parameter values, as evidenced by relative durations of hip flexion to hip extension, knee extensor phasing, and electromyogram (EMG) amplitudes. This range of behaviors could be produced by assembling different combinations of neurons from a common pool, with all six behaviors likely sharing some basic circuitry. The extent of shared circuitry may be greater between behaviors with similar timing, e.g., backpaddle and caudal scratch.