UCL Institute of Cognitive Neuroscience, Queen Square, London, UK; UCL Institute of Neurology, Queen Square, London, UK.
Donders Institute for Brain Cognition and Behaviour, Radboud University, Nijmegen, the Netherlands.
Curr Biol. 2022 Jan 10;32(1):64-73.e5. doi: 10.1016/j.cub.2021.10.033. Epub 2021 Nov 2.
Neuronal "replay," in which place cell firing during rest recapitulates recently experienced trajectories, is thought to mediate the transmission of information from hippocampus to neocortex, but the mechanism for this transmission is unknown. Here, we show that replay uses a phase code to represent spatial trajectories by the phase of firing relative to the 150- to 250-Hz "ripple" oscillations that accompany replay events. This phase code is analogous to the theta phase precession of place cell firing during navigation, in which place cells fire at progressively earlier phases of the 6- to 12-Hz theta oscillation as their place field is traversed, providing information about self-location that is additional to the rate code and a necessary precursor of replay. Thus, during replay, each ripple cycle contains a "forward sweep" of decoded locations along the recapitulated trajectory. Our results indicate a novel encoding of trajectory information during replay and implicates phase coding as a general mechanism by which the hippocampus transmits experienced and replayed sequential information to downstream targets.
神经元“回放”（replay）是指在休息时重现最近经历过的轨迹的位置细胞放电，被认为介导了从海马体到新皮层的信息传递，但这种传递的机制尚不清楚。在这里，我们表明回放使用相位编码通过与伴随回放事件的 150-250Hz“涟漪”（ripple）振荡的放电相位来表示空间轨迹。这种相位编码类似于导航过程中位置细胞放电的θ相位超前，在导航过程中，当位置细胞的位置场被穿越时，位置细胞在 6-12Hz 的θ振荡中以逐渐提前的相位放电，提供了关于自身位置的信息，该信息是速率编码的补充，也是回放的必要前提。因此，在回放过程中，每个涟漪周期都包含沿着重现轨迹的解码位置的“前向扫描”（forward sweep）。我们的结果表明在回放过程中轨迹信息的一种新的编码方式，并暗示相位编码是海马体将经历和重放的序列信息传递给下游靶标的一般机制。
