Reverse Replay of Hippocampal Place Cells Is Uniquely Modulated by Changing Reward

•Reverse, but not forward, replays are sensitive to reward context•SWRs and replay rates adaptively code the given range of reward magnitudes•Reverse replay rates are altered by changes in reward from previous experience•Reverse replay rates reflect relative reward magnitudes in the same experience

SummaryHippocampal replays are episodes of sequential place cell activity during sharp-wave ripple oscillations (SWRs). Conflicting hypotheses implicate awake replay in learning from reward and in memory retrieval for decision making. Further, awake replays can be forward, in the same order as experienced, or reverse, in the opposite order. However, while the presence or absence of reward has been reported to modulate SWR rate, the effect of reward changes on replay, and on replay direction in particular, has not been examined. Here we report divergence in the response of forward and reverse replays to changing reward. While both classes of replays were observed at reward locations, only reverse replays increased their rate at increased reward or decreased their rate at decreased reward, while forward replays were unchanged. These data demonstrate a unique relationship between reverse replay and reward processing and point to a functional distinction between different directions of replay.Video Abstract To view the video inline, enable JavaScript on your browser. However, you can download and view the video by clicking on the icon belowHelp with MP4 filesOptionsDownload video (8900 K)