WE present a biophysical model of a slowly inactivating potassium ion
current I-KS based on recent voltage-clamp data from layer V pyramidal
neurons in the cat sensorimotor cortex and show that the interplay be
tween a persistent sodium current I-NaP and I-KS is able to produce in
trinsic membrane potential oscillations in the 10- to 50-frequency ran
ge. A most notable characteristic of such rhythmicity is what may be t
ermed mixed-mode bursting, where clusters of action potentials alterna
te in time with epochs of small subthreshold oscillations.