When nervous systems are engaged with the environment, coordinated oscillations of activity in cell ensembles emerge that change rapidly as the relationship between environment and the subject evolves. Understanding the essential mechanisms determining fluctuating oscillations in brain circuits is a crucial introduction to a proper comprehension of their role in adaptive and pathological processes, as alterations of brain coordination dynamics result in behavioural deviations. In this talk, after an overview of main principles of nervous system dynamics, some possible common features underlying brain dynamics in neuropsychiatric disorders will be explored and the hypothesis will be proposed that a common aspect of neuropsychiatric disorders is less spatio-temporal fluctuations in the coordinated activity of brain cell ensembles which results in widespread and/or long-lasting brain synchrony. Specific examples of manners to perturb the transition towards hypersynchrony will be discussed, particularly in the control of epileptiform activity, illustrating how theoretical/computational observations guide experimental approaches to control abnormal brain function.