Activity-dependent changes in axonal action potential latency coordinated with synaptic potentiation in individual...

Area of Science:

• Neuroscience
• Cellular Neuroscience
• Systems Neuroscience

Background:

• Neural plasticity allows the nervous system to adapt to experiences, with synaptic plasticity being key for learning and memory.
• Action potential propagation along axons is also plastic and influences neural computation, but its coordination with synaptic plasticity is unclear.

Purpose of the Study:

• To investigate how synaptic plasticity and action potential propagation are coordinated within individual hippocampal neurons.
• To determine if changes in synaptic strength are associated with dynamic regulation of action potential timing.

Main Methods:

• Whole-cell recordings were used to simultaneously monitor synaptic responses and antidromically evoked action potentials in hippocampal CA1 pyramidal neurons.
• High-frequency stimulation induced long-term potentiation (LTP), and changes in action potential latency were measured at different axonal locations.
• LTP induction was blocked using intracellular Ca2+ chelation or NMDA receptor antagonism to assess signaling pathway involvement.

Main Results:

• Long-term potentiation (LTP) was accompanied by a transient reduction in action potential latency, which correlated with the degree of synaptic potentiation.
• Latency shortening was dependent on LTP-related signaling, as blocking LTP abolished the effect.
• The timing and spatial distribution of latency changes varied along the axon, with earlier changes at proximal sites and delayed changes at distal sites.

Conclusions:

• Synaptic potentiation is coordinated with spatially and temporally organized changes in action potential latency within individual neurons.
• These findings reveal a novel layer of activity-dependent plasticity that integrates synaptic strength with action potential timing.
• This coordinated plasticity may play a crucial role in fine-tuning neural computation and information processing.