Abstract
Hippocampal place and time cells encode spatial and temporal aspects of experience. Both have the same neural substrate, but have been modeled as having different functions and mechanistic origins, place cells as continuous attractors, and time cells as leaky integrators. Here, we show that both types emerge from two dynamical regimes of a single recurrent network (RNN) modeling hippocampal CA3 as a predictive autoencoder. The network receives simulated, partially occluded ``experience vectors" containing spatial patterns (location-specific activity sampled during environmental traversal) and/or temporal patterns (correlated activity pairs separated by ``void" intervals), and is trained to reconstruct missing input. During spatial navigation, the network generates stable attractor-like place fields. But trained on temporally structured inputs, the network produces sequentially broadened fields, recapitulating time cells. By varying spatio-temporal input patterning, we observe hidden units transition smoothly between time cell-like and place cell-like representations. These results suggest a shared origin, but task-driven difference, between place and time cells.
Abstract (translated)
海马体的位置细胞和时间细胞分别编码经验的时空方面。两者具有相同的神经基质，但传统上被建模为具有不同的功能和机制起源：位置细胞作为连续吸引子，时间细胞作为渗漏积分器。在此，我们证明这两种细胞类型均源于一个单一循环神经网络（RNN）的两种动态机制，该网络将海马CA3区建模为预测自编码器。该网络接收模拟的、部分遮挡的“经验向量”，其中包含空间模式（环境遍历期间采样的位置特异性活动）和/或时间模式（由“空隔”间隔分隔的相关活动对），并被训练以重建缺失的输入。在空间导航过程中，网络产生稳定的类吸引子位置场。但在接受时间结构输入训练后，网络产生序列展宽的场，重现了时间细胞特征。通过改变时空输入模式，我们观察到隐藏单元在时间细胞样与位置细胞样表征之间平滑过渡。这些结果提示位置细胞和时间细胞具有共同起源，但受任务驱动产生差异。
URL
https://arxiv.org/abs/2604.00036
