Fig. 2

CSF-cNs are minimally activated during fictive escapes when no muscle contraction occurs.

(a) Schematic view of the experimental setup combining 2-photon laser scanning microscope for calcium imaging and electrophysiological recordings of the ventral nerve root. 10 ms-long water jets delivered to the otic vesicle triggered fictive escapes in paralyzed larvae. (b) Lateral view showing expression of GCaMP6f in MNs in the double transgenic larva Tg(mnx1:Gal4, UAS:GCaMP6f;cryaa:mCherry) and in CSF-cNs in Tg(pkd2l1:gal4, UAS:GCaMP6f;cryaa:mCherry). ROIs indicate cells included in the analysis. Only the dorsalmost MNs were analyzed in the mnx1 line. Scale bar: 20 µm. (c) Typical calcium transients recorded in MNs (blue) and in CSF-cNs (red) during fictive escapes; ‘stimulus’ indicates when the water jet was triggered, average response in coloured lines. (d) Quantification of calcium transient amplitude in MNs and CSF-cNs (each data point represents one recording from one cell; plots use median as the measure of central tendency; inset is the cumulative histogram of calcium responses). Responses in both populations are greater than baseline (204 MNs from 6 larvae: mean ΔF/F=1.2, P<1.0 × 10^-8; 192 CSF-cNs from 7 larvae: mean ΔF/F=0.042, P=3.78 × 10^-8), but CSF-cNs exhibit significantly less activity than MNs (P=0.014).