ROLES OF GABA, GLUTAMATE, ACETYLCHOLINE AND STN STIMULATION ON THALAMIC VM IN RATS

THE effects of high frequency stimulation of the subthalamic nucleus ( STN) and of iontophoretic application of different neurotransmitters o n neuronal activities of the ventromedial thalamic nucleus (VM) were i nvestigated in rats. GABA, when applied iontophoretically, inhibited V M neuronal activity while bicuculline, L-glutamic acid and acetylcholi ne enhanced the firing rates of the same VIM neurons. High frequency s timulation of the STN increased VM neuronal activity in a frequency-de pendent manner, which could be blocked by MK801. These results suggest that GABAergic, cholinergic and glutamatergic input information conve rge in the same VM neurons and that an increase in the delivery of glu tamatergic neurotransmitter activities in the VM is involved in the pr ocess of high frequency stimulation of the STN.