Comparison of decay time constants (τ_decay) of spontaneous synaptic currents (mEPCs) between wild-type and acetylcholinesterase-null (zim^tm205) 72–82-hpf larval zebrafish. (A) Sample mEPCs from wild-type fast (left) and wild-type slow (right) skeletal muscle. The 10–90% decay phase is fit to a single-exponential function (red) to obtain τ_decay. (B) Sample mEPCs from zim^tm205 fast (left) and zim^tm205 slow (right) skeletal muscle, each fit in the same manner as those in A. (C) The frequency histogram of τ_decay values for individual mEPCs from wild-type fast muscle (black; n = 14 recordings), zim^tm205 fast muscle (red; n = 28 recordings), wild-type slow muscle (green; n = 15 recordings), and zim^tm205 slow muscle (blue; n = 15 recordings). (D) The mean τ_decay values for each recording (filled circles) along with the overall mean ± SD (open circle) are shown for each condition.