Ionic mechanisms for intrinsic slow oscillations in thalamic relay neurons

Biophys J. 1993 Oct;65(4):1538-52. doi: 10.1016/S0006-3495(93)81190-1.


The oscillatory properties of single thalamocortical neurons were investigated by using a Hodgkin-Huxley-like model that included Ca2+ diffusion, the low-threshold Ca2+ current (lT) and the hyperpolarization-activated inward current (lh). lh was modeled by double activation kinetics regulated by intracellular Ca2+. The model exhibited waxing and waning oscillations consisting of 1-25-s bursts of slow oscillations (3.5-4 Hz) separated by long silent periods (4-20 s). During the oscillatory phase, the entry of Ca2+ progressively shifted the activation function of lh, terminating the oscillations. A similar type of waxing and waning oscillation was also observed, in the absence of Ca2+ regulation of lh, from the combination of lT, lh, and a slow K+ current. Singular approximation showed that for both models, the activation variables of lh controlled the dynamics of thalamocortical cells. Dynamical analysis of the system in a phase plane diagram showed that waxing and waning oscillations arose when lh entrained the system alternately between stationary and oscillating branches.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Biological Clocks
  • Biophysical Phenomena
  • Biophysics
  • Calcium / metabolism*
  • Cats
  • Kinetics
  • Membrane Potentials
  • Models, Neurological
  • Neurons / physiology
  • Potassium / metabolism
  • Thalamus / cytology
  • Thalamus / physiology*


  • Potassium
  • Calcium