1. Vesicular release probabilities define effective convergence.
Vesicular release probabilities define effective convergence. A, Normalized peak IPSC amplitude decreases as the spontaneous spiking frequency increases in single cartwheel cells. Red dots are generated by the two-pool depletion model. Black dots are generated by the same model but lacking the low-Pr pool. Gray dotted line indicates the assumed effective inhibition strength needed to inhibit a fusiform cell from spiking (50% of maximum IPSC). B, Number of effective inputs predicted by the model when two pools are used (red dots) or only when the model lacks the low-Pr pool (black dots). The effective number is derived by dividing the effective inhibition strength (0.5) by each dot in A. When the synapse lacks the low-Pr pool, it requires a much larger number of inputs to effectively inhibit fusiform cell spiking compared with when both pools are present. For example, when cartwheel cells spontaneously fire at 10 Hz, it only requires 2–3 cells to provide effective inhibition when the two pools are present at the synapse. The effective convergence ratio increases to ∼30 cartwheel cells when the synapse lacks the low-Pr pool.
Hsin-Wei Lu, and Laurence O. Trussell J. Neurosci. 2016;36:
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