Cross interval histograms of all 57 MU firing patterns for the NS basic model and the four methods of MUs’ synchronization using Δt ± 6 ms.

The cross-interval histograms are depicted with maximal bin normalization, considering a bins width of 1 ms within a bin interval of ± 15 ms. The amplitude of the central bin, presenting a minimal cross-interval difference of ± 0.5 ms, is proportional to the derived index of synchronization (CISI).