This single cell example shows release dynamics of two synapses innervating the same IHC from either pillar or modiolar side. iGluSnFR signals (bandstop filtered at 33.3 Hz) in response to 50-ms-long step depolarizations to the given depolarization voltages are depicted (ruptured patch-clamp, 10 mM intracellular EGTA, 5 mM [Ca2+]e). The middle panel shows ΔF images of iGluSnFR, recorded from the mid-section of the IHC. * depict the first detected response in the given synapse. Note that pillar synapse 1 is already active at -49 mV, while modiolar synapse 2 starts responding only at -41 mV. (Scale bar 2 μm) A' The normalized iGluSnFR-AUC as a function of depolarization voltage. Dynamic range and V1/2 of the synapses are depicted in the lower panel. 