Figure 5.

Aberrant timing and decreased recovery of spontaneous activity at hair-cell ribbon synapses in nsfa^I209N/st53 mutants

(A) Representative traces of spontaneous afferent activity in WT (green and orange traces) and nsfa^I209N/st53 mutants (brown and blue traces).

(B and C) Mean ISI (B) and ISI CV (C) for spontaneous activity for WT (n = 8 cells) and nsfa^I209N/st53 mutants (n = 4 cells). Mean ± SEM are shown; p values were determined by unpaired Student’s two-tailed t tests; *p < 0.05, **p < 0.01, ***p < 0.001.

(D–G) Recurrence plots reveal regularity of the timing of consecutive spikes (spike time n plotted versus spike time n – 1) for the four cells shown in (A). Note the greater spread and clustering in three quadrants for the mutant panels, indicating a more irregular, bursting pattern in mutant neurons.

(H–K) Recovery of spontaneous activity is delayed in nsfa^I209N/st53 mutants. (H) Representative traces show the return of spontaneous activity after a prolonged stimulation of hair cells at 60 Hz. (I and J) Corresponding recurrence plots for the first 900 recovered spontaneous spikes for the recordings shown in (H).

(K) Recovery of spontaneous spike rate as shown by cumulative spike number over time following cessation of 90 s of 60-Hz stimulation. Shading represents error. n indicates cell number.