Quantitative Analysis Linking Inner Hair Cell Voltage Changes and Postsynaptic Conductance Change: A Modelling Study

Figure 9

The temporal response of the voltage dependent structures of the synapse anatomy resulting in a change in the postsynaptic conductance. The stimulating signal used is a 100 ms depolarising pulse of −30 mV (left column) and −50 mV (right column). (a) An illustration is shown of the superimposed opening and closing responses of a selection of a few calcium channels that are within a 50 nm radius around a randomly selected position just under the synaptic ribbon. The distance of 50 nm was chosen for clarity of the figure. Note that the most active channel is shown in red. (b) The free calcium ion concentration at the postulated “calcium sensor” of some of the synaptic vesicles that are ready for release. In blue the vesicle whose pattern of release is shown in the next panel. In green a selection of a few of its neighbouring vesicles, thus showing the differences of spatial allocation in calcium sensing. (c) The vesicle release mechanism discrete steps are shown with a red “” marking the release events. Note that having five bound onto the exocytotic mechanism does not always guarantee release (insert). (d) The aggregated response from the release of the synaptic vesicles is changing the postsynaptic conductance in response to the internal cell being depolarised.

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