“…For example, neurons neither have any tendency to behave periodically on their own, nor are subject to any periodic forcing; nevertheless, they organize to produce a regular motion perceived at the macroscopic scale [28]. Various models of large families of interacting particles showing self-sustained oscillations have been proposed; we refer the reader to [1,2,4,5,7,[9][10][11]13,15,16,19,20], where possible mechanisms leading to a rhythmic behavior are discussed and many related references are given.…”