Data from: A load-based mechanism for inter-leg coordination in insects

Animals rely on an adaptive coordination of legs during walking. However, which specific mechanisms underlie coordination during natural locomotion remains largely unknown. One hypothesis is that legs can be coordinated mechanically based on a transfer of body load from one leg to another. To test this hypothesis, we simultaneously recorded leg kinematics, ground reaction forces and muscle activity in freely walking stick insects (Carausius morosus). Based on torque calculations, we show that load sensors (campaniform sensilla) at the proximal leg joints are well suited to encode the unloading of the leg in individual steps. The unloading coincides with a switch from stance to swing muscle activity, consistent with a load reflex promoting the stance-to-swing transition. Moreover, a mechanical simulation reveals that the unloading can be ascribed to the loading of a specific neighbouring leg, making it exploitable for inter-leg coordination. We propose that mechanically mediated load-based coordination is used across insects analogously to mammals.动物在行走过程中依赖腿部的自适应协调运动。然而，自然运动状态下腿部协调的具体机制仍未被充分阐明。有假说提出，腿部可通过机械方式实现协调，核心原理为身体载荷从单条腿部转移至其他腿部。为验证该假说，我们对自由行走的竹节虫（Carausius morosus）同步记录了腿部运动学数据、地面反作用力以及肌肉活动信号。通过扭矩计算分析，我们发现腿部近端关节处的载荷传感器（campaniform sensilla，钟形感器）能够有效编码单一步态周期中腿部的卸荷过程。腿部卸荷与肌肉活动从站立相到摆动相的转换同步发生，这与促进站立-摆动转换的载荷反射机制相符。此外，力学模拟结果显示，目标腿部的卸荷可归因于特定相邻腿部的加载，这一机制可用于腿部间的协调控制。我们提出，机械介导的载荷依赖型协调机制在昆虫类群中广泛存在，其功能与哺乳动物中的同类机制相似。