Neuronal oscillations within the electroencephalogram beta and gamma bands (15-80 Hz) are associated with intense mental activity and cognitive function in general. Specifically, recent advances have implicated gamma oscillations in the processing of sensory stimuli and demonstrated that synchronous gamma oscillations, appearing concurrently in spatially separate brain regions, can induce beta activity. beta activity generated in this manner represents established synchronous communication between brain regions and is thought to represent a neuronal network correlate of the "binding phenomenon" in cognitive theory. This review will outline the mechanisms of generation of these oscillations at the cellular and network level, and will highlight the effects of drugs that may modify these mechanisms. Possible modification of fast oscillations by disease processes and clinical intervention are discussed.