Quantifying the Spatiotemporal Dynamics of Locomotory Waves*

Locomotor waves in animals show intricate spatiotemporal dynamics. For example, in the roundworm C. elegans, body waves can travel in opposite directions and at different speeds. Current quantification and modeling methods cannot extract information about such non-uniform wave propagation. Here, we develop methods to quantify locomotor wave dynamics at a high spatiotemporal resolution. We compute the frequency, wavenumber, and wave-velocity as a function of space and time. Additionally, we can decompose the body waves into a superposition of interpretable wave patterns. Applying these analyses to video data of C. elegans worms, we reveal that wave properties vary non-monotonically along the body, with head and tail showing higher frequency oscillations compared to the body. Analysis of transgenic worms suggests that motor neurons might be involved in maintaining the phase relationships along the body, while premotor neurons govern the frequency and amplitude of body bends. This work lays the foundation to examine and model the oscillatory neural network activities that organize C. elegans locomotion. It is also generally applicable to the locomotion of other slender-bodied animals.