Dynamics of reflex cocontraction in hermit crab abdomen: experiments and a systems model.
Dynamics of reflex cocontraction in hermit crab abdomen: experiments and a systems model.
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寄居蟹腹部反射协同收缩的动力学：实验和系统模型。
DOI：
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发表时间：
1993
影响因子：
2.5
通讯作者：
W. Chapple
中科院分区：
文献类型：
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作者：
W. Chapple
1.寄居蟹腹部腹面浅层肌(VSM)的伸展和释放都激活了完整动物和隔离腹部的VSM运动神经元。2.在VSM的牵拉和释放过程中，通过细胞内记录单个运动神经元支配的肌纤维来研究这种反射。右侧第四节的三个运动神经元对伸展和释放都有反应，并以持续约250ms的相性爆发作出反应。两个强直运动神经元的爆发由两部分组成，短爆发持续10-20ms，从伸展开始潜伏期为60-90ms；长爆发长度可变，潜伏期为120ms。用不同幅值和速度的斜拉图表明，第一分量与力的二阶导数的绝对值成正比，第二分量与力的一阶导数的绝对值成正比。3.牵拉和释放VSM还可同时在背侧浅肌和VSM环肌的运动神经元(纵向VSM的功能性拮抗剂)，以及同一节段的对侧同源和下一个前段的同侧同源中诱发相性爆发。这种共同激活的效果是在任何方向的扰动下使腹部变得僵硬。4.牵拉或释放VSM中的时相机械感受器可引起这种反射。对分离的肌肉进行等长电刺激也会激活它们，表明它们正在传递力量的变化，并表明它们通过正反馈来增加肌肉僵硬。5.建立了该反射的数学系统模型，该模型由两条平行通路激活运动神经元组成。第一个路径产生与力的二阶导数的绝对值成比例的信号，第二个路径产生与力的一阶导数成比例的信号。来自两个通路的信号的总和通过适应过程进行滤波，然后是代表肌肉激活动力学的低通滤波器。然后，肌肉激活信号被反馈给多个肌肉力量。6.使用该模型模拟产生了伸展和释放的相位爆发，并再现了这种反射的频率依赖性。这种反射的主要作用是增强肌肉僵硬。
1. Both stretch and release of the ventral superficial muscles (VSM) in the abdomen of the hermit crab, Pagurus pollicarus, activate the VSM motoneurons in the intact animal and in the isolated abdomen. 2. This reflex was studied by recording intracellularly from muscle fibers innervated by single motoneurons during stretch and release of the VSM. The three motoneurons of the right fourth segment respond to both stretch and release with a phasic burst lasting approximately 250 ms. The burst in the two tonic motoneurons has two components, a short burst lasting 10-20 ms, with a latency from the beginning of stretch of 60-90 ms, and a longer burst of variable length, with a latency of 120 ms. Ramp stretches of different amplitudes and velocities were used to show that the first component is proportional to the absolute value of the second derivative of force and the second component to the absolute value of the first derivative of force. 3. Stretch and release of the VSM also simultaneously evoke phasic bursts in the motoneurons of the dorsal superficial muscles and the VSM circular muscles (functional antagonists of the longitudinal VSM), as well as in contralateral homologues of the same segment and in ipsilateral homologues of the next anterior segment. The effect of this coactivation is to stiffen the abdomen in response to perturbations in any direction. 4. Stretch or release of phasic mechanoreceptors in the VSM evokes this reflex. Isometric electrical stimulation of the isolated muscle also activates them, showing that they are transducing changes in force and suggesting that they operate to increase muscle stiffness by positive feedback. 5. A mathematical systems model of this reflex, composed of two parallel pathways activating the motoneurons, was constructed. The first pathway produces a signal proportional to the absolute value of the second derivative of force, the second pathway a signal proportional to the first derivative of force. The sum of the signals from the two pathways is filtered by an adaptation process, which is followed by a low-pass filter representing muscle activation kinetics. The muscle activation signal is then fed back to multiple muscle force. 6. Simulations using this model generate the phasic bursts to stretch and release as well as reproducing the frequency dependence of this reflex. The predominant action of this reflex is to enhance muscle stiffness.