Network oscillations are postulated to be instrumental for synchronizing the activity of anatomically distributed populations of neurons. Results from recent studies on the physiology of cortical interneurons suggest that through their interconnectivity, they can maintain large-scale oscillations at various frequencies (4-12 Hz, 40-100 Hz and 200 Hz). We suggest that networks of inhibitory interneurons within the forebrain impose co-ordinated oscillatory 'contexts' for the 'content' carried by networks of principal cells. These oscillating inhibitory networks may provide the precise temporal structure necessary for ensembles of neurons to perform specific functions, including sensory binding and memory formation.