English: Representative recording in clustered networks. The movie shows the spontaneous activity in the network depicted in Figure 1, showing the first of recorded activity. The original sequence was acquired at frames/s. It is reproduced here 15 times faster. The ignition of a cluster is revealed by a sharp increase in the fluorescence signal. Bursts of activity correspond to the ignition of clusters in a short time window. It is worth remarking the rich activity, the strong modularity, and the repetition of some sequences. Activity was driven solely by excitatory connectivity, with inhibition blocked with bicuculline.