Ventral Striatal Dopamine Increases following Hippocampal Sharp-Wave Ripples

Leading theories suggest that hippocampal replay drives offline learning through coupling with an internal teaching signal such as ventral striatal dopamine (DA); however, the relationship between hippocampal replay and dopamine is unknown. Simultaneous recording of putative hippocampal replay events (dorsal CA1 sharp-wave ripples, SWRs) and fiber photometry of ventral striatal DA in mice revealed a significant increase in DA following SWRs, peaking ∼0.3 s after SWRs. This result establishes for the first time a core theoretical requirement of offline learning in the mammalian brain.