The synaptic ribbon is critical for sound encoding at high rates and with temporal precision

• DOI: 10.7554/elife.29275
• Publication Date: 2018-01-12T13:00:23Z
• Authors: Philippe Jean; David Lopez de la...; Susann Michanski; Lina María Jaime ...; Rituparna Chakrab...; Maria Magdalena P...; Jakob Neef; SangYong Jung; Mehmet Gültas; Stephan Maxeiner; Andreas Neef; Carolin Wichmann; Nicola Strenzke; Chad Grabner; Tobias Moser
• Keywords: Ribbon synapse; Active zone; Spiral ganglion

We studied the role of synaptic ribbon for sound encoding at synapses between inner hair cells (IHCs) and spiral ganglion neurons (SGNs) in mice lacking RIBEYE (RBEKO/KO). Electron immunofluorescence microscopy revealed a lack ribbons an assembly several small active zones (AZs) each contact. Spontaneous sound-evoked firing rates SGNs their compound action potential were reduced, indicating impaired transmission ribbonless IHC-SGN synapses. The temporal precision was recovery SGN-firing from adaptation indicated slowed vesicle (SV) replenishment. Activation Ca2+-channels shifted to more depolarized potentials exocytosis reduced weak depolarizations. Presynaptic Ca2+-signals showed broader spread, compatible with altered Ca2+-channel clustering observed by super-resolution microscopy. postulate that disruption is partially compensated multi-AZ organization. remaining deficit indicates function SV-replenishment regulation.