Activity-Dependent Changes in Axonal Action Potential Latency Coordinated with Synaptic Potentiation in Individual Hippocampal Neurons.

Neural plasticity enables the nervous system to adapt its structure and function in response to experience. Although synaptic plasticity is a central cellular mechanism underlying learning and memory, action potential propagation along axons is also subject to plastic regulation and critically shapes neural computation. However, how these distinct forms of plasticity are coordinated within individual neurons remains poorly understood. Here, we simultaneously monitored synaptic responses and antidromically evoked action potentials in hippocampal CA1 pyramidal neurons from male rats using whole-cell recordings. High-frequency stimulation reliably induced long-term potentiation (LTP) and was accompanied by a delayed yet transient reduction in antidromic action potential latency. The magnitude of latency shortening correlated with the degree of synaptic potentiation across multiple post-high-frequency stimulation time windows, including a late phase during which synaptic responses remained persistently elevated. Blocking the induction of LTP by intracellular Ca