The inhibitory effects of thalamic stimulation on the spinal transmission of nociceptive information in the rat

Abstract

Single unit recordings were made in the lumbar dorsal horn of the halothane anaesthetized rat. Trains of electrical stimuli applied to the ipsilateral and contralateral ventrobasal thalamic complex could powerfully inhibit the activities of both convergent cells and neurones responding only to noxious inputs. Other neuronal classes were not influenced by the stimulation. The noxious and tactile related activities of the convergent cells were reduced by the thalamic stimulation. Electrolytic lesions of nucleus raphe magnus markedly reduced the inhibitory influences. The relevance of these effects to the analgesic effects of thalamic stimulation in man and animals is discussed.