After hyperpolarization conductance time-course and repetitive firing in a motoneurone model with early inactivation of the slow potassium conductance system.

Early inactivation of the slow potassium conductance system (GK), responsible for the spike afterhyperpolarization (AHP) in spinal alpha motoneurones, has been introduced in a motoneurone model whose GK kinetics give rise to an exponentially decaying AHP conductance. After this modification, the model displays a plateau shaped time-course of the AHP conductance and a faster shortening of the first interval during repetitive firing induced by current steps of increasing intensities. Both features increase the resemblance between the model and the motoneurone behaviour. Comparison with real motoneurones also suggests that GK inactivation may be more developed in "slow" than in "fast" motoneurones.