The study by Sirota et al. investigates the communication between the neocortex and hippocampus during sleep in rodents. The authors found a robust correlation between neuronal discharges in the somatosensory cortex and the hippocampus on both slow and fine time scales. Neuronal bursts in deep cortical layers, associated with sleep spindles and delta waves/slow rhythms, triggered hippocampal discharges related to fast (ripple) oscillations. This suggests that oscillation-mediated temporal links coordinate specific information transfer between neocortical and hippocampal cell assemblies, which may be crucial for memory consolidation. The study used multisite recording of unit and field activity in the hippocampus and somatosensory cortex, demonstrating that neocortical activity can time the occurrence of hippocampal sharp waves and ripples. These findings provide insights into how the interaction between the neocortex and hippocampus during sleep supports the encoding and consolidation of memories.The study by Sirota et al. investigates the communication between the neocortex and hippocampus during sleep in rodents. The authors found a robust correlation between neuronal discharges in the somatosensory cortex and the hippocampus on both slow and fine time scales. Neuronal bursts in deep cortical layers, associated with sleep spindles and delta waves/slow rhythms, triggered hippocampal discharges related to fast (ripple) oscillations. This suggests that oscillation-mediated temporal links coordinate specific information transfer between neocortical and hippocampal cell assemblies, which may be crucial for memory consolidation. The study used multisite recording of unit and field activity in the hippocampus and somatosensory cortex, demonstrating that neocortical activity can time the occurrence of hippocampal sharp waves and ripples. These findings provide insights into how the interaction between the neocortex and hippocampus during sleep supports the encoding and consolidation of memories.