Response characteristics of tooth pulp-driven postsynaptic neurons in the spinal trigeminal subnucleus oralis of the cat.
Neuronal activity in the spinal trigeminal subnucleus oralis in response to electrical tooth stimulation was recorded in the anaesthetized cat in order to compare the electrophysiological characteristics of the oralis neurons with those of subnucleus caudalis and interpolaris neurons recorded in previous studies. The most sensitive oralis neurons had lower thresholds and shorter latencies than the most sensitive caudalis and interpolaris neurons. The thresholds of the oralis neurons were lower and their strength-duration curves flatter than those depicting liminal dental pain in man but similar to those depicting liminal jaw reflexes in the cat. Noxious conditioning stimulus elevated the threshold of only 1 of 10 neurons tested. The converging input from the skin and oral mucosa was from low-threshold mechanoreceptors. The results indicate that the response properties of the subnucleus oralis neurons differ significantly from those of other spinal subnuclei. Human pain thresholds cannot be explained by the liminal response properties of oralis neurons. These neurons might be important in the mediation of liminal reflex events evoked by dental stimuli.
Huopaniemi
T
T
Department of Physiology, University of Helsinki, Finland.
Jyväsjärvi
E
E
Carlson
S
S
Lindroos
F
F
Pertovaara
A
A
D000818:Animals; D001369:Axons / Q000502:physiology; D002415:Cats; D003782:Dental Pulp / Q000502:physiology*; D004558:Electric Stimulation; D009474:Neurons / Q000502:physiology*; D009475:Neurons, Afferent / Q000502:physiology; D010146:Pain / Q000503:physiopathology; D012684:Sensory Thresholds / Q000502:physiology; D013116:Spinal Cord / Q000166:cytology / Q000502:physiology*; D013569:Synapses / Q000502:physiology*; D012668:Trigeminal Ganglion / Q000502:physiology*