Analysis of spontaneous activity in neuronal cultures through recurrence plots: impact of varying connectivity

We analyzed spontaneous activity of cortical neuronal networks in vitro using recurrence plots (RPs). Our data encompasses fluorescence traces of average network activity from two experimental explorations, namely the development of connections during the maturation of the network and the gradual weakening of connections through chemical action. The dynamical richness of the networks in these connectivity-evolving scenarios was examined through recurrence quantification analysis. Measures such as determinism and laminarity were used to portray the degree of uniformity and periodicity of the spontaneous activity patterns. The analysis shows that RPs are a powerful tool to visualize and interpret neuronal networks dynamics, and pinpoint its hallmarks.