Figure 6.

Longitudinal imaging suggests systematic changes in the complement of presynaptic inputs in developing vestibulospinal neurons. A, Two-photon volumes of vestibulospinal neurons in a Tg(nefma:GAL4);Tg(UAS:GCaMP6s) larva during longitudinal imaging experiments at 4 and 7 dpf. Colored overlays indicate the same neurons located in the volume across the two time points. B, Mean peak calcium response of all neurons at 4 dpf are correlated with their mean peak response at 7 dpf (ρ = 0.51) but is more variable than expected by remounting alone (fit line ± SD of residuals from repeated mounting experiment in Fig. 2D). C, Mean peak ΔF/F responses across all responsive neurons for ipsilateral and contralateral rolls of 10, 20, and 30° magnitudes at 4 dpf (black) and 7 dpf (magenta). Error bars indicate ± SEM. D, Probability distributions of longitudinal changes in ipsilateral (top) and contralateral (bottom) calcium response sensitivity (n = 70 cells; see above, Materials and Methods). Dashed vertical lines represent cutoffs for significant sensitivity change. E, Longitudinal sensitivity changes in individual neurons across ipsilateral and contralateral roll tilts. F, Longitudinal sensitivity changes for ipsilateral (top) and contralateral (bottom) roll tilts split by neurons that have significant magnitude-dependent responses to roll steps in that direction at 4 dpf (Early-Tuned, green) versus nontuned at 4 dpf (Non-Tuned, black).