Figure 9.

A TERPS and RCaMP imaging tool can identify excitatory monosynaptic connections between cells. A, Representative trace showing that optogenetic activation of A27h expressing NaChBac, in the presence of 2 μm TTX, induces a clear change in calcium levels (indicated by a change in RCaMP fluorescence) in aCC (∼200 A.U. above baseline, n = 5). The addition of the cholinergic blocker mecamylamine (200 μm) to the same preparation abolishes this response (right-hand panel). All that remains is a smaller light-induced artifact because of the activation of the blue LED. B, Representative trace for optogenetic activation of A31k-expressing NaChBac, in the presence of 2 μm TTX, shows that the activation of this premotor interneuron does alter calcium levels in aCC (no change in arbitrary units above baseline, in addition to the peak explained in C; n = 5). C, Representative trace for flashing Canton-S wild-type larvae, showing that it is light from the blue LED that produces the recording artifact (arrowhead; n = 1).