Figure 3

Ace-mScarlet reports single action potentials in cultured neurons with high sensitivity and brightness. (a) Representative fluorescence traces from Ace-mScarlet (top) and Ace2N-mNeon (bottom) faithfully track single action potentials and subthreshold changes in potential in simultaneous electrophysiology recordings. (b) Each sensor’s average fluorescence traces (colored solid lines) in response to single action potentials (n = 180 spikes from 6 neurons each; shaded region represents mean ± s.d.) closely match the average waveform of electrically recorded action potentials (black line). (c) Ace-7aa-mScarlet’s, Ace-8aa-mScarlet’s, VARNAM’s, and Ace2N-mNeon’s average peak response to action potentials (n = 10 neurons each; mean ± s.e.m.). (d) ΔF/F vs. brightness of Ace-7aa-mScarlet, Ace-8aa-mScarlet, Ace2N-mNeon, VARNAM (n = 10 neurons each; mean ± s.e.m.) and FlicR1 (n = 5 neurons; mean ± s.e.m.) in response to single action potentials. Ace-mScarlet variants had both higher sensitivity and brightness than other red GEVIs. Dashed lines represent d’ isocontours (Methods).