title: Responses of single lingual nerve fibers to thermal and chemical stimulation.
abstract: The goals of this study were to characterize the responses of: (1) thermally-sensitive fibers of the lingual branch of the trigeminal nerve to cooling from 35 degrees to 10 degrees C at a rate of 1 degrees C/s; and (2) these neurons to a mid-range concentration of NaCl (150 mM), glucose (150 mM), citric acid (0.3 mM), and quinine-HCl (3 mM) at 35 degrees and 25 degrees C. A cluster analysis of 47 neurons' responses to cooling revealed two major groups and one minor group. Group 1 neurons (n=19) had a shorter latency, exhibited faster time-to-peak activity, and responded over a smaller range of temperature compared to Group 2 neurons (n=22). Group 3 neurons (n=6) exhibited the longest response latency and responded over a wider cooler range of temperature. Twenty-five out of thirty-one thermally-sensitive, non-tactile lingual neurons responded weakly to at least one chemical stimulus, with some neurons responding to 2, 3, or all 4 chemical stimuli. Group 1 neurons responded to more chemical stimuli at 35 degrees C, while Group 2 neurons responded more at 25 degrees C. Under their optimal temperature conditions, Group 1 and Group 2 neurons responded most often to citric acid and least often to glucose, with NaCl and Q-HCl eliciting an intermediate number of responses. As a whole, the responses of thermally-sensitive fibers to chemical stimulation were modest at best with an absence of chemical specificity. There was no evidence of a 'best' stimulus, although there was a suggestion of temporal coding.
authors.affiliation: The Florida State University, Department of Psychology, Tallahassee, FL 32306-1270, USA.
authors.forename: D W
authors.initials: DW
authors.lastname: Pittman
authors.forename: R J
authors.initials: RJ
authors.lastname: Contreras
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001831:Body Temperature / Q000502:physiology*; D002614:Chelating Agents / Q000494:pharmacology; D019343:Citric Acid / Q000494:pharmacology; D004594:Electrophysiology; D005947:Glucose / Q000494:pharmacology; D006358:Hot Temperature; D008036:Lingual Nerve / Q000166:cytology / Q000502:physiology*; D008297:Male; D009125:Muscle Relaxants, Central / Q000494:pharmacology; D009412:Nerve Fibers / Q000187:drug effects / Q000502:physiology*; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D011803:Quinine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D012965:Sodium Chloride / Q000494:pharmacology; D013268:Stimulation, Chemical; D013649:Taste / Q000502:physiology*; D014110:Touch / Q000502:physiology; D014276:Trigeminal Nerve / Q000166:cytology / Q000502:physiology
chemical_list: D002614:Chelating Agents; D009125:Muscle Relaxants, Central; D019343:Citric Acid; D012965:Sodium Chloride; D011803:Quinine; D005947:Glucose