The theory of non-linear dynamic systems applied to biological neurone networks where a determinist chaotic behaviour was proved explains in a surprising way the deposition and rapid recollection of memory traces, By means of phasic transition and synchronization of oscillations it is possible to interpret the epileptic activity as a manifestation of universal properties of determinist chaotic systems, Models of cerebral activity based on chaotic neurones ave a better idea of the actual behaviour of biological neurones.