The hippocampus encodes distinct contexts with unique patterns of activity. Representational shifts with changes in context, referred to as remapping, have been extensively studied. However, less is known about transitions between representations. In this study, we leverage a large dataset of neuronal recordings taken while rats performed an olfactory memory task with a predictable temporal structure involving trials and intertrial intervals (ITIs), separated by salient boundaries at the trial start and trial end. We found that trial epochs were associated with stable hippocampal representations despite moment‐to‐moment variability in stimuli and behavior. Representations of trial and ITI epochs were far more distinct than spatial factors would predict and the transitions between the two were abrupt. The boundary was associated with a large spike in multiunit activity, with many individual cells specifically active at the start or end of each trial. Both epochs and boundaries were encoded by hippocampal populations, and these representations carried information on orthogonal axes readily identified using principal component analysis. We suggest that the hippocampus orthogonalizes representations of the trial and ITI epochs and the activity spike at trial boundaries might serve to drive hippocampal activity from one stable state to the other.

中文翻译：

---

海马状态在试验时期之间的边界转换。

海马体编码具有独特活动模式的不同背景。随着上下文变化的表征变化，称为重新映射，已被广泛研究。然而，人们对表征之间的转换知之甚少。在这项研究中，我们利用了大鼠执行嗅觉记忆任务时拍摄的大量神经元记录数据集，该任务具有可预测的时间结构，涉及试验和试验间隔 (ITI)，在试验开始和试验结束时由显着边界分隔。我们发现，尽管刺激和行为在瞬间发生变化，但试验时期与稳定的海马表征相关。试验和 ITI 时代的表现比空间因素预测的要明显得多，而且两者之间的过渡是突然的。该边界与多单元活动的大峰值有关，许多单个细胞在每次试验的开始或结束时都特别活跃。时代和边界都由海马种群编码，这些表示在正交轴上携带信息，使用主成分分析很容易识别。我们建议海马体正交化试验和 ITI 时期的表示，试验边界处的活动峰值可能有助于将海马活动从一种稳定状态驱动到另一种稳定状态。