Changes in Postural Syntax Characterize Sensory Modulation and Natural Variation of C. elegans Locomotion
The left half of the figure (A-C) shows data from ZX46 worms expressing channelrhodopsin in the cholinergic motor neurons and the right half (D-F) from AQ2026 worms expressing channelrhodopsin in ASH, a neuron that detects aversive stimuli, as well as PVQ and ASI. (A, D) R2 between original body angles and nearest-neighbour template over time. The blue line is the mean and the gray shading indicates the standard deviation (n = 23 in A; n = 34 in D). Yellow box indicates light stimulation period. (B, E) The relative probability of observing each posture over time. Colour indicates whether a posture is over-represented (red) or underrepresented (blue) at each time. Postures with similar temporal profiles are clustered independently in B and E for visualization. (C, F) The top 2 n-grams that are most significantly overrepresented (red) or underrepresented (blue) during the indicated time periods for n = 1–3 for each strain. Grey numbers show the row number for each posture in the corresponding heatmap. Dots indicate worm head, dorsal and ventral sides are as indicated by the arrows. The gray dashed lines approximately connect body bends from one posture to the next and can be used to distinguish forward from reverse locomotion. Lines with a negative slope indicate body bends propagating backwards and therefore forward locomotion. Lines with a positive slope show reversals.