Figure 9.

Comparing reliability across species with different wiring conditions. The reliability (measured as the CV) of the summated postsynaptic response as a function of the number of connections (A, n = 1; B, n = 12; C, n = 41), Pr, and transmission mode (i.e., UVR, MVR, no local variability). A, Single contacts, like that observed in the mammalian cochlea, exhibit highly variable responses. In this scenario, local variability in the synaptic response limits the reliability of transmission. B, C, Multiple synaptic contacts onto each fiber, like that observed in the amphibian papilla, dramatically improve reliability and minimize the total impact of local variability in the synaptic response. These conditions also greatly expand the range of release probabilities that can provide highly reliable signals.