Cover picture: Illustration of a music score generated by the spikes of parallel-recorded hippocampal pyramidal neurons (MIDI code) in the behaving rat. Recurring patterns of spikes can be recognized by listening to the hippocampal "music" in real time (FTP://speedy2.md.huji.ac.il/pub/neuron.mid). The middle panel was extracted from traces of local field and spike activity during slow-wave sleep dominated by 200 Hz intermittent field ripples. The panel was distorted by a whirl effect to mimic the oscillatory nature of population events and the structure that generated it. For details, see the article by Nádasdy et al., in this issue (pages 9497-9507).