Figure 2. Functional network interaction in hippocampal cultures becomes stereotypic after four weeks in vitro.

(A) Schematic representation of the network burst analysis. Analysis of network interaction was carried out on multi-channel recordings of activity (5 representative channels in the left panel; rat hippocampal culture at DIV21) and was based for detection of non-zero periods of coordinated bursting (gray area in the middle panel) reflecting a functional connection between distinct neuronal clusters. (B) The stabilization of all the NB parameters after DIV28 demonstrated that spontaneous formation of the network connectivity requires four weeks in vitro and is associated with synchronization of the bursting activity of spatially remote neuronal clusters within 20–30 ms. ***P < 0.001; ns: non-significant (Duncan test). Data are shown as mean ± S.E.M.