Neuromodulation of Axon Terminals

Area of Science:

• Neuroscience
• Cellular Biophysics

Background:

• Understanding cellular compartment sensitivity is crucial for neuromodulation.
• Experimental models for central nervous system (CNS) stimulation are lacking, particularly regarding axon terminal responses.

Purpose of the Study:

• To investigate and quantify the biophysical changes in axon terminals during weak direct current stimulation (DCS).
• To elucidate the role of axon terminal polarization in both suprathreshold and subthreshold neuromodulation.

Main Methods:

• Simultaneous intracellular recording from neuron soma and axon terminals (blebs) in mouse cortical slices.
• Extracellular stimulation using weak, sustained (DC) uniform electric fields.

Main Results:

• Axon terminals exhibited 4x greater sensitivity to electrical polarization compared to somas.
• Even minor axon terminal polarization (<2 mV) significantly altered action potential dynamics (amplitude, duration, conduction velocity).

Conclusions:

• Axon terminal polarization is a key mechanism in neuromodulation.
• Suprathreshold CNS stimulation activates action potentials at terminals, while subthreshold methods modulate synaptic efficacy via polarization.
• Neuromodulation influences analog-digital information processing through axon polarization and altered action potential dynamics.