Data from: The speed–curvature power law in Drosophila larval locomotion

We report the discovery that the locomotor trajectories of Drosophila larvae follow the power-law relationship between speed and curvature previously found in the movements of human and non-human primates. Using high-resolution behavioural tracking in controlled but naturalistic sensory environments, we tested the law in maggots tracing different trajectory types, from reaching-like movements to scribbles. For most but not all flies, we found that the law holds robustly, with an exponent close to three-quarters rather than to the usual two-thirds found in almost all human situations, suggesting dynamic effects adding on purely kinematic constraints. There are different hypotheses for the origin of the law in primates, one invoking cortical computations, another viscoelastic muscle properties coupled with central pattern generators. Our findings are consistent with the latter view and demonstrate that the law is possible in animals with nervous systems orders of magnitude simpler than in primates. Scaling laws might exist because natural selection favours processes that remain behaviourally efficient across a wide range of neural and body architectures in distantly related species.

本研究报道一项发现：果蝇（Drosophila）幼虫的运动轨迹遵循速度与曲率间的幂律关系——该规律此前仅在人类及非人类灵长类动物的运动中被观测到。本研究在可控且自然化的感官环境中，采用高分辨率行为追踪技术，针对形成涵盖类似伸手动作至乱涂轨迹等多种轨迹类型的果蝇幼虫，验证了该幂律规律。研究发现，在绝大多数（而非全部）果蝇个体中，该规律稳健成立，其幂指数趋近于3/4，而非几乎所有人类运动场景中常见的2/3，这表明除纯粹的运动学约束外，还存在附加的动力学效应影响。关于灵长类动物中该规律的起源，目前已提出多种假说：其一假说认为该规律源于皮层计算，另一假说则认为其与黏弹性肌肉特性及中枢模式发生器（central pattern generators）相关。本研究结果与后一种假说相符，同时证明：即便神经系统复杂度比灵长类低数个数量级的动物，也能够呈现这类幂律规律。标度律之所以普遍存在，可能是因为自然选择更青睐那些在远缘物种的多样神经与躯体结构中，仍能保持行为高效性的过程。