Figure 5.

One-Sided Silencing Depressed cIN Inhibition and dIN Excitation and Necessity for cIN Inhibition in dIN Rebound Firing

(A) The last cycles of a swimming episode, in which light (yellow bar) stopped swimming within one cycle. Different synaptic currents are labeled (c is used as a control cycle).

(B) Normalized synaptic currents in dINs in cycle 0, as shown in (A), in light silencing trials (eight dINs, 53 trials). Tonic inward current (IC) was measured as the difference between the clamping current at rest (dashed line in A) and the current level just before each cIN IPSC.

(C) Five superimposed trials with −DC injections, aligned to the last m.n. burst, showing synaptic currents in cycle 0.

(D) Normalized synaptic currents in dINs in cycle 0 in −DC injection experiments (seven dINs, 51 trials). Synaptic currents are normalized to those in control cycles in (B) and (D). All recordings are from the ArCh-GFP negative side or the side without −DC injections into dINs.

(E) dIN usually fires a single spike at the onset of a depolarizing pulse (220 pA, 1 s) but can also fire on rebound.

(F) The boxed area is expanded to show rebound spikes following cIN IPSPs (seven trials overlayed). IPSPs failing to evoke dIN rebound spikes are blue.

(G) The size of cIN IPSPs that evoked dIN rebound firing (black and gray) and the size of IPSPs that failed to evoke firing (blue). Error bars represent SE. ^∗∗p < 0.01.