Supplementary Figure 2: Classification of tethered behavior on the ball

(a) Swing-stance periods (black or white, respectively) during a walking bout as defined by videography. Note that at steady forward walking (from 0.5 to 4 s), the fly displays tripod gate (see zoom-in, N=6 flies). (b) Examples of a subset of the first ten principal components (PCs) of the side-view fly video recordings (Fig. 1a,b). Asterisks indicate the PCs whose scores are shown in (c). (c) Time-varying scores for different PCs. A zoom-in into PC5’s scores reveals a periodic behavior of a principal component associated with leg movement. (d) A wavelet transformation of PC5 scores further indicates the bandwidth of the signal, matching the mean cycle period obtained from the swing-phase analysis. (e) The PCs scores and their wavelet transform (c,d) were used to train JAABA (top schematic) to classify walking and other possible behaviors of the fly on the ball (bottom color-coded image). (f) Example of a 1-minute trial displaying the fly’s forward (grey top trace), and angular (grey bottom trace) velocity signals during walking (pink background) and non-walking (blue background) segments. For angular velocity, CCW turns are positive sign values. For forward velocity, negative sign indicates backward walking. Arrowheads show activity segments (i.e., non-walking but non-stationary segments).