Identification of tonic Ib and phasic Is motoneuron GAL4 drivers. A, Comparison of synaptic and biophysical properties of Ib and Is motoneurons in Drosophila larvae. B, Confocal image of UAS-CD8-GFP driven by MN1-Ib GAL4 (GMR94G06) in the third instar larval VNC from the FlyLight Project GAL4 collection. Arrows denote the paired MN1-Ib cell bodies in each abdominal segment, and arrowheads denote GFP expression in axons exiting the VNC. Scale bar, 50 µm. C, Diagram of MN1-Ib innervation in a larval abdominal hemisegment. D, Immunostaining for anti-GFP (green) to label MN1-Ib and HRP (magenta) to label all axons in a MN1-Ib GAL4; UAS-CD8-GFP third instar larva. Muscles M1 and M2 are indicated. Scale bar, 20 µm. E, Diagram of MNISN-Is and MNSNb/d-Is innervation in a larval abdominal hemisegment. F, Immunostaining for anti-GFP (green) to label MNIs and HRP (magenta) to label all axons in a MNIs GAL4 (6-58); UAS-CD8-GFP third instar larva. Muscles M1 and M2 are indicated. Scale bar, 20 µm.