Figure 3. Coordination of migratory cells: running and rotating modes.

(a) The measurements of group polarization and angular momentum of a movie over time. The values of group polarization and angular momentum are within [0, 1]. We can project to a 2D space and classify the cluster movement into running and rotating. (b,c) Probability distribution of group polarization and angular momentum of four movies with purely rotating (b) or running (c). There are 116 time points for cluster rotating and 134 time points for running. In this 2D space, we can clearly see two distinct motion regimes, indicated by white arrows. (d,e) GMM fitting of group polarization and angular momentum of rotating (red surface) and running (blue surface). The decision boundary of these two modes, indicated by the yellow line, is the edge between the red and blue surface. (f) Polar axis (yellow) and plane (light grey) for a running movie. The relative position of the two polar cells is relatively stable during the running mode (Supplementary Movie 5). (g) Polar axis and polar plane for a rotating movies. The polar cell rotates with the whole cluster during the rotating mode. (Supplementary Movie 5).