This model, diverged from oscillatory parameters seen in live cells and failed to produce characteristic ectopic discharge patterns. Here we show that use of a more complete set of Na+ conductances--which includes several delayed components--enables simulation of the entire repertoire of oscillation-triggered electrogenic phenomena seen in live dorsal root ganglion (DRG) neurons. This includes a physiological window of induction and natural patterns of spike discharge. An INa+ component at 2-20 ms was particularly important, even though it represented only a tiny fraction of overall INa+ amplitude. With the addition of a delayed rectifier IK+ the singlet firing seen in some DRG neurons can also be simulated. The model reveals the key conductances that underlie afferent ectopia, conductances that are potentially attractive targets in the search for more effective treatments of neuropathic pain.
Model Type: Neuron or other electrically excitable cell
Cell Type(s): Dorsal Root Ganglion (DRG) cell
Currents: I K; I Sodium; Late Na
Model Concept(s): Bursting; Ion Channel Kinetics; Pathophysiology
Simulation Environment: NEURON
Implementer(s): Devor, Marshall [marshlu at vms.huji.ac.il]
Kovalsky Y, Amir R, Devor M. (2009). Simulation in sensory neurons reveals a key role for delayed Na+ current in subthreshold oscillations and ectopic discharge: implications for neuropathic pain. Journal of neurophysiology. 102 [PubMed]