The simultaneous recording of the time series formed by the timing of neuronal discharges produced by a cell assembly reveals important features of the dynamic of information processing in the brain. Experimental evidence of firing sequences with precision of few milliseconds over intervals lasting hundreds of milliseconds have suggested that particular topologies of converging/diverging chains of neuronal assemblies may propagate the activity with the necessary time accuracy. Simulation studies of critical phases of brain development suggest the emergence of stimulus-driven cell assemblies that will form the 'wiring' of the adult brain out of randomly connected large scale networks. These results are presented from the viewpoint of dynamical systems and chaotic attractors.