Event-related neural activities: what about phase?

The main topic of this overview is an analysis of the concepts of phase and synchrony, as used in neurophysiology, in their various meanings. A number of notions related to the concepts of phase and synchrony, which are incorporated in contemporary neurophysiology, particularly in the domain of neuro-cognitive physiology are discussed. These notions need a critical examination, since their use sometimes is not clear, or it may even be ambiguous. We present some of these concepts, namely (a) (des)synchronization, (b) phase resetting, (c) phase synchrony and phase/time delays, and (d) phase clustering within one signal, while discussing what type of neuronal activities may underlie these EEG phenomena.