Our hosting provider will be performing UPS maintenance on Tuesday, Oct 25, 2016 between 8 AM and 5 PM PDT. SciCrunch searching services will be down during this time.

Preparing your results

Our searching services are busy right now. Your search will reload in five seconds.

Forgot Password

If you have forgotten your password you can enter your email here and get a temporary password sent to your email.

Distinct subsets of unmyelinated primary sensory fibers mediate behavioral responses to noxious thermal and mechanical stimuli.


Behavioral responses to painful stimuli require peripheral sensory neurons called nociceptors. Electrophysiological studies show that most C-fiber nociceptors are polymodal (i.e., respond to multiple noxious stimulus modalities, such as mechanical and thermal); nevertheless, these stimuli are perceived as distinct. Therefore, it is believed that discrimination among these modalities only occurs at spinal or supraspinal levels of processing. Here, we provide evidence to the contrary. Genetic ablation in adulthood of unmyelinated sensory neurons expressing the G protein-coupled receptor Mrgprd reduces behavioral sensitivity to noxious mechanical stimuli but not to heat or cold stimuli. Conversely, pharmacological ablation of the central branches of TRPV1(+) nociceptors, which constitute a nonoverlapping population, selectively abolishes noxious heat pain sensitivity. Combined elimination of both populations yielded an additive phenotype with no additional behavioral deficits, ruling out a redundant contribution of these populations to heat and mechanical pain sensitivity. This double-dissociation suggests that the brain can distinguish different noxious stimulus modalities from the earliest stages of sensory processing.

Pubmed ID: 19451647


  • Cavanaugh DJ
  • Lee H
  • Lo L
  • Shields SD
  • Zylka MJ
  • Basbaum AI
  • Anderson DJ


Proceedings of the National Academy of Sciences of the United States of America

Publication Data

June 2, 2009

Associated Grants

  • Agency: NINDS NIH HHS, Id: NS14627
  • Agency: NINDS NIH HHS, Id: P01NS048499
  • Agency: Howard Hughes Medical Institute, Id:

Mesh Terms

  • Animals
  • Behavior, Animal
  • Brain
  • Cold Temperature
  • Diphtheria Toxin
  • Hot Temperature
  • Mice
  • Mice, Mutant Strains
  • Nerve Fibers, Unmyelinated
  • Pain
  • Receptors, G-Protein-Coupled
  • Stress, Mechanical
  • TRPV Cation Channels