Intrinsic persistent firing in CA1 encodes elapsed time across behaviorally relevant scales

The ability to encode and maintain temporal relationships is crucial for learning, predicting, and forming episodic memories. While hippocampal time cells and entorhinal temporal context cells are well-established in vivo, it remains unclear whether single neurons can sustain representations of elapsed time over multi-second intervals, independent of synaptic drive. Here, using whole-cell patch-clamp recordings in rodent hippocampal CA1 slices under synaptic blockade, we show that following a brief current pulse, many neurons exhibit exponentially decaying firing rates with a broad distribution of time constants extending to tens of seconds. This indicates that single neurons possess intrinsic mechanisms capable of covering behaviorally relevant temporal scales. These results highlight that single neurons can encode temporal information over more than an order of magnitude, providing a potential cellular substrate for temporal coding in the brain.