FIGURE 5

FIGURE 5

Spontaneous calcium activity at the presynapse requires Ca_V1.3 channels. (A) Diagram illustrating the hair cells with the hair bundles highlighted by a dashed box where we measure their spontaneous calcium activity. The structure of a single ribbon synapse at the base of a hair cell is illustrated, as well as the calcium channels beneath it. (B–D) Representative memGCaMP6s temporal traces show that disruption of Ca_V1.3a channels using cav1.3a mutants (B,C) or pharmacological block using 10 µM isradipine (D) does not impact spontaneous activity in apical hair bundles. (E) Diagram illustrating the hair cells with the presynaptic area highlighted by a dashed box where we measure the spontaneous presynaptic calcium activity. (F–H) Representative memGCaMP6s temporal traces show that disruption of calcium channels using cav1.3a mutants (F–G) or pharmacological block using 10 µM isradipine (H) completely blocked spontaneous activity at the hair cell presynapse. All measurements were performed in immature hair cells at day 3.