Adaptive mechanisms coupling the four limbs during quadrupedal locomotion

在包括人类在内的陆生哺乳动物中，行走涉及所有四肢的协调活动。 虽然在行走过程中协调手臂和腿的机制知之甚少，但据认为，位于脊髓的颈和腰骶水平的功能网络之间的联系也参与其中。 本研究的目的是调查一些反射途径，耦合的颈和腰骶神经网络的脊髓在四足跑步机运动的猫，在这些网络的条件下，可以在功能上解耦。 为了实现这一目标，四足运动将在4向分裂带跑步机上进行研究，该跑步机可以分离每条腿的节奏（即速度），从而分离控制每条肢体的脊髓网络的功能。 猫将植入记录和刺激电极，分别记录四肢的肌肉活动和刺激外周神经。 将进行神经刺激以引起耦合手臂和腿的反射反应。 例如，供应足背和前爪的神经将被刺激以分别在前肢和后肢的肌肉中引起反射反应。 我们的目标是研究这些反射通路在四足运动时，四肢走在同一速度和条件下，每个肢体的节奏是独立控制使用各种组合。 这种方法将展示反射通路如何在这些条件下适应，并且还提供关于感觉反馈在调节位于一个腰带（例如手臂）到另一个腰带（例如腿）的网络活动中的作用的机械见解。 实验数据将提供一个框架，系统地研究神经结构参与的控制和适应四足运动。

In terrestrial mammals, including humans, walking involves coordinated activity of all four limbs. Although mechanisms coordinating the arms and legs during walking are poorly understood, it is thought that a linkage between functional networks located at the cervical and lumbosacral levels of the spinal cord are involved. The goal of this study is to investigate some of the reflex pathways that couple the cervical and lumbosacral networks of the spinal cord during quadrupedal treadmill locomotion in the cat, in conditions where these networks can be functionally uncoupled. To accomplish this goal, quadrupedal locomotion will be studied on a 4-way split-belt treadmill that can uncouple the rhythm (i.e. speed) of each leg, thus separating the functioning of the spinal networks controlling each limb. Cats will be implanted with recording and stimulating electrodes to record muscular activity in all four limbs and to stimulate peripheral nerves, respectively. The nerve stimulation will be done to evoke reflex responses that couple the arms and legs. For instance, the nerves supplying the dorsum of the foot and forepaw will be stimulated to evoke reflex responses in muscles of the forelimbs and hindlimbs, respectively. The goal is to study these reflex pathways during quadrupedal locomotion when the four limbs walk at the same speed and under conditions where the rhythm of each limb is independently controlled using various combinations. Such an approach, will demonstrate how reflex pathways adapt under these conditions, and also provide mechanistic insight as to the role of sensory feedback in regulating the activity of networks located at one girdle (e.g. arms) to another (e.g. legs). The experimental data will provide a framework to systematically investigate the neural structures involved in the control and adaptation of quadrupedal locomotion.