Fig. 1

RME neurons are synchronously inhibited during backward locomotion. a Schematic of RME. b Representative fluorescent and transmitted-light microscopy images of a transgenic animal (jqIs72) expressing G-CaMP7 and DsRed during forward movement (Top) and backward movement (Bottom). Pseudocolor images show the fluorescence intensity ratio (R = G-CaMP7/DsRed). Scale bar represents 10 μm. c A representative calcium trace of RME during spontaneous locomotion. The gray line shows raw data, and the black line shows the moving average data across a 0.27 s window. Periods of forward locomotion (green bars) and backward locomotion (red bars) are indicated on the top of the trace. d Quantitative analysis of fluorescence ratio changes from each RME cell type. n = 8–10 from 6 to 9 animals. **P < 0.01, Student’s two-tailed t-test. Error bars, SEM. e Typical calcium dynamics of RMEL (red) and RMED (blue) associated with the directional change from forward (green bar) to backward (red bar) locomotion. In both neurons, calcium decrease begins at the onset of reversal and persists during backward movement. Light colors show raw data, and dark colors show moving averages of ratio values (R). f ChR2-mediated photostimulation (blue bars) of ASH and simultaneous calcium imaging of RME. g Mean fluorescence ratio changes during the optogenetically induced reversals (n = 12 from seven animals) were comparable with those during spontaneous reversals (n = 14 from six animals). n.s. = not significant, Student’s two-tailed t-test. Error bars, SEM