The paper by Kopell et al. explores the different synchronization properties of gamma (30–70 Hz) and beta (12–29 Hz) rhythms in the CA1 region of the hippocampus. Using a simplified model, they demonstrate that these rhythms employ distinct dynamical mechanisms based on different ionic currents. Gamma rhythms are better suited for local computations, while beta rhythms are better adapted for higher-level interactions involving distant brain structures. The study shows that beta rhythms can synchronize over longer conduction delays, which gamma rhythms cannot tolerate. This is attributed to the presence of an additional after-hyperpolarization (AHP) current in beta rhythms, which provides a feedback mechanism for timing. The analysis is supported by large-scale models, which confirm that beta rhythms can maintain synchronization even with conduction delays exceeding 10 ms, whereas gamma rhythms cannot. The findings suggest that the hierarchical use of oscillation frequencies in the brain may reflect the anatomical hierarchy of sensory information processing.The paper by Kopell et al. explores the different synchronization properties of gamma (30–70 Hz) and beta (12–29 Hz) rhythms in the CA1 region of the hippocampus. Using a simplified model, they demonstrate that these rhythms employ distinct dynamical mechanisms based on different ionic currents. Gamma rhythms are better suited for local computations, while beta rhythms are better adapted for higher-level interactions involving distant brain structures. The study shows that beta rhythms can synchronize over longer conduction delays, which gamma rhythms cannot tolerate. This is attributed to the presence of an additional after-hyperpolarization (AHP) current in beta rhythms, which provides a feedback mechanism for timing. The analysis is supported by large-scale models, which confirm that beta rhythms can maintain synchronization even with conduction delays exceeding 10 ms, whereas gamma rhythms cannot. The findings suggest that the hierarchical use of oscillation frequencies in the brain may reflect the anatomical hierarchy of sensory information processing.