Evaluation of the effective and functional connectivity estimators for microelectrode array recordings during in vitro neuronal network maturation

During maturation, neurons and neuronal ensembles interact and build connections. Changes in the network structure have effects on the overall electrophysiological activity, and consequently on the observable connectivity. In this paper, we assessed effective and functional connectivities during neuronal network development by means of directed connectivity and synchronization, respectively. For that, we analyzed in vitro dissociated mouse cortical neuronal networks during four weeks using microelectrode arrays. Functional and effective connectivities were estimated with CorSE and transfer entropy (TE), respectively. Here, we describe the advantages of the methods relative to each other. We observed that the functional connectivity analysis may provide networking information in earlier phases of network development than effective connectivity. On the other hand, effective connectivity analysis provides information on the sources and targets of information flows. By corroborative analysis using CorSE and TE, one can investigate possible effects of early synchronizations on information transfer during the later stages of network development. In conclusion, using effective and functional connectivity assessments jointly provides for enhanced analysis of the development of information transfer during the structural development of a neuronal network.