Fig. 8: Electrical IHC coupling coordinates Ca2 + channel activity. | Nature Communications

Fig. 8: Electrical IHC coupling coordinates Ca2 + channel activity.

From: Macromolecular and electrical coupling between inner hair cells in the rodent cochlea

Fig. 8

The signaling steps of IHCs and their synapses, simulated in the Neuron modeling environment for three non-coupled IHCs (left) and three coupled IHCs with a junctional resistance of 25 MΩ (right). a Simplified representation of IHCs, color-coded for the simulation results presented below. b Depiction of the sinusoidal mechanical stimulus (identical for all three cells). c Realization of the stochastic gating of mechanotransducer channels (specific for each cell, identical for coupled and uncoupled cells). d Membrane voltage variations of the three IHCs. They differ from each other because the mechanotransduction currents differ, but that difference is mitigated by electric coupling (right). e Illustration of the average open probability, as would result from very many realizations of Ca2+ channel gating given the voltage trajectories above. f Different conductance states (O open, C closed) of one channel in each IHC. g Modeling stimulus-secretion-coupling and refractoriness for 35,000 independent realizations of (f), an approximate probability to observe an AP in a SGN during a 200 µs window is calculated. Numbers in the central column are Pearson correlation coefficients rp, averages of correlations between pairs of traces from two different IHCs. In parenthesis are the average correlations between the IHC parameter and the sinusoidal stimulus. For those correlations, time lags of 0.3 ms for the voltage and 0.5 ms for the Ca2+ channels are compensated for. AP action potential, IHC inner hair cell.

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