• movement disorders;
  • basal ganglia;
  • discharge pattern;
  • spike morphology;
  • single unit recordings


In the dtsz hamster, a model of idiopathic paroxysmal dystonia, recent findings indicated a decreased neuronal activity within the globus pallidus (GP) and an impaired gamma aminobutyric acid (GABA)ergic function when compared to nondystonic controls. Therefore, in the present study, extracellular single-unit recordings combined with systemical application of a subconvulsant prodystonic dose of pentylenetetrazole (PTZ) were used to compare the electrophysiological properties of GP neurons in anesthetized dtsz hamsters and nondystonic controls. The spontaneous discharge rate of GP neurons was not decreased but a trend towards a wide-ranged distribution was found in mutants compared to controls. Since the single-unit activity of striatal neurons was recently shown to be significantly increased in dtsz hamsters, the lack of significant changes in GP discharge rates was unpredicted. We suggest that this is due to antagonistic convergent striatal and subthalamic inputs and to lateral monosynaptic inhibition known for striatum and GP. While no significant changes of the discharge rate of GP neurons could be detected, the spike morphology was significantly altered in dtsz hamsters, suggesting subtle impaired information processing in the GP. The lack of marked changes in basal firing pattern may be related to the anesthesia. Administration of PTZ (25 mg/kg i.p.) at a subconvulsant dose, which aggravates dystonia in awake dtsz hamsters, seemed to induce more marked changes in spike morphology and firing pattern in mutants than in controls, although the discharge rate did not differ significantly between both animal groups in response to PTZ. In view of recent findings, we assume that GABAergic dysfunctions in dystonic hamsters are of regionally different extent. J. Neurosci. Res. 57:894–905, 1999. © 1999 Wiley-Liss, Inc.