Fig. 6: The conduction and fidelity of spikes at the nerve terminal are impaired in Scn2a cKO mice.

A Illustration of the calyx of Held recording with a bipolar stimulator placed in the midline of the brainstem. B Representative traces of presynaptic action potential (AP) train stimulated at 200 Hz from control (black) and Scn2a cKO (red) mice. Gray arrowheads indicate AP failure during the train in Scn2a cKO mice. C (Left) Violin plots of AP failure rate from control and Scn2a cKO mice stimulated at varied frequencies (from 50 Hz to 500 Hz, 11 control cells vs. 18 cKO cells, p = 0.0048). Solid and dashed lines represent median and first and third quartile, respectively. (Right) The average of AP failure rate at varied stimulating frequencies. D The average stimulating intensity to initiate a single AP (Threshold intensity, TI, 11 control cells vs. 9 cKO cells) from control and Scn2a cKO. p values from two-tailed unpaired t-test shown with asterisk. E Representative traces of 200 Hz AP train from Scn2a cKO mice stimulated with TI, 20% increment from TI, and 40% increment from TI. Note that increasing stimulation intensity reduced AP failures. F (Left) Violin plots of 200 Hz AP failure rate reduced by incremental stimulating intensities in control and Scn2a cKO. Circles and squares indicate individual datapoint (11 control cells vs. 9 cKO cells). (Right) Summary from the left showing the average failure rate from incremental stimulating intensities. Data are shown as mean ± s.e.m. The median and quartiles were presented with solid and dashed line respectively, and p-values from two-way ANOVA with multiple comparison shown at the top of figure (C, F). * p < 0.05, ** p < 0.01. Source data are provided as a Source Data file.