The Journal of Neurophysiology Vol. 85 No. 2 February 2001, pp. 523-538
Copyright ©2001 by the American Physiological Society
1The Center for Hearing Sciences and Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205; and 2Division of Otolaryngology-Head and Neck Surgery, Department of Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7070
Kanold, Patrick O. and
Paul B. Manis.
A Physiologically Based Model of Discharge Pattern Regulation by
Transient K+ Currents in Cochlear Nucleus Pyramidal
Cells. J. Neurophysiol. 85: 523-538, 2001. Pyramidal cells in the dorsal cochlear nucleus (DCN) show three
characteristic discharge patterns in response tones: pauser, buildup,
and regular firing. Experimental evidence suggests that a rapidly
inactivating K+-current
(IKIF) plays a critical role in
generating these discharge patterns. To explore the role of
IKIF, we used a computational model
based on the biophysical data. The model replicated the dependence of
the discharge pattern on the magnitude and duration of hyperpolarizing
prepulses, and IKIF was necessary to
convey this dependence. Phase-plane and perturbation analyses show that responses to depolarization are critically controlled by the amount of
inactivation of IKIF. Experimentally,
half-inactivation voltage and kinetics of
IKIF show wide variability. Varying
these parameters in the model revealed that half-inactivation voltage,
and activation and inactivation rates, controls the voltage and time
dependence of the model cell discharge. This suggests that pyramidal
cells can adjust their sensitivity to different temporal patterns of inhibition and excitation by modulating the kinetics of
IKIF. Overall,
IKIF is a critical conductance
controlling the excitability of DCN pyramidal cells.