This model investigates the impact of mitochondria on action potential propagation in thin, unmyelinated axons. Mitochondria act as regions of increased internal resistivity along the axon. Simulations showed that when the propagating action potential encounters a mitochondrion, conduction velocity decreases delaying action potential propagation, an effect that is stronger in small axons. The model is based on measurements from electron micrographs of unmyelinated axons of the HVC neurons that project to the premotor nucleus RA (robust nucleus of the arcopallium) (HVC(RA) neurons) in canaries. The model neuron consists of a passive soma with an axon containing fast sodium and delayed rectifier potassium conductances in addition to a leak conductance. The description of the active currents was taken from the model of Cohen et al. 2020 (https://modeldb.science/260967). The axon consists of two types of sections, one containing a mitochondrion and the other only axoplasm. The mitochondrion containing compartments have increased internal resistivity that depends on the cross-sectional mitochondrial occupancy.
Model Type: Axon; Neuron or other electrically excitable cell
Region(s) or Organism(s):
Cell Type(s):
Currents: I Potassium; I Sodium
Receptors:
Genes:
Transmitters:
Model Concept(s): Axonal Action Potentials; Delay
Simulation Environment: NEURON
Implementer(s): Castelfranco, Ann M
References:
Castelfranco AM, Alcami P. (2025). Mitochondria delay action potential propagation. Communications biology. 8 [PubMed]