Synchronization of neural activity in the brain is involved in a variety of brain functions including perception, cognition, memory, and motor behavior. Excessively strong, weak, or otherwise improperly organized patterns of synchronous oscillatory activity appear to contribute to the generation of symptoms of different neurological and psychiatric diseases. However, neuronal synchrony is frequently not perfect, but rather exhibits intermittent dynamics. So the same synchrony strength may be achieved with markedly different temporal patterns of activity (roughly speaking oscillations may go out of the synchronous state for many short episodes or few long episodes). I will discuss this situation from two perspectives: the phase-space perspective and associated considerations of dynamical systems theory and time-series analysis perspective. I will then proceed with the application of this analysis to the neurophysiological data in healthy brain, Parkinson's disease, and in drug addiction disorders.