Figure 4. The behavioural patterns of individual animals.

(a) Multi-colour bars show snapshots (95 s) of classifier scores for multiple trials of two individual flies. Blue triangles indicate a behavioural transition more frequent in fly no. 1 and yellow triangles indicate a transition more frequent in fly no. 2. Colours here and in b and d indicate behaviour type. In a–f, distinct trials for each fly were recorded on separate days. (b) Pie charts depicting fraction of time spent performing each behaviour for distinct trials from two individual animals, based on 2-h recordings per experiment per animal. (c) Left: spatial visualization of principal components (PCs) 1 and 2 underlying the inter-trial variance in fraction of time spent per behaviour in b. Shapes indicate multiple trials of an individual fly. Right: mean pairwise distance between and within flies in PC1–PC2 space at left. Bars are ±s.e.m. across n=153 inter-fly and n=12 intra-fly pairwise distances. See Supplementary Methods. (d) Ethograms of the same trials from b. Arrows indicate direction of transition and thickness indicates frequency. Self-transitions are omitted for clarity. Triangles as in a. See Supplementary Methods. (e) Left: spatial visualization of principal components 1 and 2 underlying the variance in the ethograms from d. Shapes indicate multiple trials across days of an individual fly. Right: mean pairwise distance between and within flies in PC1–PC2 space at left. Bars are ±s.e.m. across n=153 inter-fly and n=12 intra-fly pairwise distances. See Supplementary Methods. (f) Individuality in the average y coordinates of the left (red) and right (blue) hind legs during the transition from postural adjustment to motion. Shaded regions indicate ±s.e.m., with n varying according to the number of times each fly performed a postural adjustment–forward/backward running transition in each trial (48≤n≤282). (g) Running speed (z-score normalized across all experimental phases) during optomotor experiments as a function of stimulus. Bars are ±s.d. across n=5 flies. Blue/black patterns are representative top-to-bottom kymographs of the presented visual stimulus. CL, closed loop; OL, open loop. See Supplementary Methods. (h) Inter-fly variability (s.d.) of four different locomotor parameters, as a function of optomotor stimulus loop-closure status. Bar means in top graph correspond to error bars in g. The s.e. bars on the estimates of variability were determined by bootstrap resampling. L3 stride period and length were determined by inter-peak frequency analysis and are representative of all other legs. Forward-motion burst intervals were determined by the mode of the intervals between peaks of ball forward/backward velocity.