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

Figure 2

(a) and (b) show a top view of the active zone which has roughly 90 calcium channels. The synaptic ribbon extent is outlined by the green line as an oval circle, the filled circles represent calcium channels, and the open circles represent synaptic vesicles (red signifies ribbon tethered vesicles, whereas blue signifies freely floating vesicles). The line indicates the radius of the active zone. (a) illustrates an immature synapse characterised by the uniform distribution spread of calcium channels shown in (c). (b) illustrates a mature synapse characterised by the normal distribution spread of calcium channels with the peak of distribution being the centre of the synapse shown in (d). (c) and (d) show the probability distribution of channel placement along the active zone diameter. (c) is a uniform distribution limited to the extent of the active zone diameter. (d) is a normal distribution with a standard deviation (SD) equal to one-fourth of the radius, that is, . Note that the selection of is a conjecture based on visual inspection and descriptions of the maturation of the synapse [6, 9, 26].

(a)

(b)

(c)

(d)