Modeling motoneurons after spinal cord injury: persistent inward currents and plateau potentials

A single-compartment conductance-based computational model to mimic the behavior of rat tail motoneurons after acute and chronic spinal cord injury (SCI) was developed. The model includes a calcium-dependent potassium current, IK(Ca), that contributes to after hyperpolarizations. In the chronic SCI model, the presence of sodium and calcium persistent inward currents (PICs) causes plateau potentials resulting in prolonged self-sustained firing. The interaction between the calcium PIC and IK(Ca) affects the magnitude and duration of plateau potentials as well as the hysteresis seen during injected current ramps. The model responses mimic experimental observations and may explain the spasticity observed after chronic SCI.