Intrinsic Properties of Nucleus Reticularis Thalami Neurones of the Rat Studied in Vitro

J Physiol. 1989 Sep;416:111-22. doi: 10.1113/jphysiol.1989.sp017752.

Abstract

1. Neurones of the nucleus reticularis thalami of the rat were studied by intracellular recordings from in vitro slices. The resting membrane potential was -56.28 +/- 5.86 mV (mean value +/- S.D.); input resistance was 43.09 +/- 9.74 M omega; the time constant tau was 16.51 +/- 3.99 ms. At the resting membrane potential tonic firing is present, while at membrane potentials more negative than -60 mV a burst firing mode gradually prevails. 2. Prolonged depolarizing current pulses superimposed on a steady hyperpolarization consistently activated sequences of burst-after-hyperpolarization complexes. The all-or-none burst response consisted of Na+-mediated, TTX-sensitive fast action potentials superimposed on a low threshold spike (LTS). The burst was followed by a stereotyped after-hyperpolarization lasting 100-120 ms (BAHP), with a maxima -85 mV. The BAHP was blocked by Cd2+ and apamine but not by 8-Br cyclic AMP. The early component of BAHP was significantly attenuated by TEA. The oscillatory rhythmic discharges were abolished by agents which blocked the BAHP. 3. The presence of strong after-hyperpolarizing potentials (SAHP and BAHP) in RTN neurones plays a significant role in determining two different functional states, defined as tonic and oscillatory burst firing modes, respectively.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / drug effects
  • Animals
  • Apamin / pharmacology
  • Cadmium / pharmacology
  • Cyclic AMP / pharmacology
  • Electric Stimulation
  • In Vitro Techniques
  • Membrane Potentials
  • Rats
  • Rats, Inbred Strains
  • Tetraethylammonium
  • Tetraethylammonium Compounds / pharmacology
  • Tetrodotoxin / pharmacology
  • Thalamic Nuclei / physiology*

Substances

  • Tetraethylammonium Compounds
  • Cadmium
  • Apamin
  • Tetrodotoxin
  • Tetraethylammonium
  • Cyclic AMP