A possible neural mechanism for photosensitivity in chronic pain

Melissa E. Martenson, Omar I. Halawa, Karen J. Tonsfeldt, Charlene A. Maxwell, Nora Hammack, Scott Mist, Mark Pennesi, Robert (Rob) Bennett, Kim M. Mauer, Kim Jones, Mary Heinricher

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Patients with functional pain disorders often complain of generalized sensory hypersensitivity, finding sounds, smells, or even everyday light aversive. The neural basis for this aversion is unknown, but it cannot be attributed to a general increase in cortical sensory processing. Here, we quantified the threshold for aversion to light in patients with fibromyalgia, a pain disorder thought to reflect dysregulation of pain-modulating systems in the brain. These individuals expressed discomfort at light levels substantially lower than that of healthy control subjects. Complementary studies in lightly anesthetized rat demonstrated that a subset of identified pain-modulating neurons in the rostral ventromedial medulla unexpectedly responds to light. Approximately half of the pain-facilitating "ON-cells" and pain-inhibiting "OFF-cells" sampled exhibited a change in firing with light exposure, shifting the system to a pronociceptive state with the activation of ON-cells and suppression of OFF-cell firing. The change in neuronal firing did not require a trigeminal or posterior thalamic relay, but it was blocked by the inactivation of the olivary pretectal nucleus. Light exposure also resulted in a measurable but modest decrease in the threshold for heat-evoked paw withdrawal, as would be expected with engagement of this pain-modulating circuitry. These data demonstrate integration of information about light intensity with somatic input at the level of single pain-modulating neurons in the brain stem of the rat under basal conditions. Taken together, our findings in rodents and humans provide a novel mechanism for abnormal photosensitivity and suggest that light has the potential to engage pain-modulating systems such that normally innocuous inputs are perceived as aversive or even painful.

Original languageEnglish (US)
Pages (from-to)868-878
Number of pages11
JournalPain
Volume157
Issue number4
DOIs
StatePublished - Apr 1 2016

Fingerprint

Chronic Pain
Light
Pain
Somatoform Disorders
Neurons
Fibromyalgia
Smell
Brain Stem
Rodentia
Healthy Volunteers
Hypersensitivity
Hot Temperature
Brain

Keywords

  • Descending control
  • Fibromyalgia
  • Multisensory hypersensitivity
  • Pain-modulation
  • Rostral ventromedial medulla

ASJC Scopus subject areas

  • Clinical Neurology
  • Anesthesiology and Pain Medicine
  • Neurology
  • Pharmacology

Cite this

Martenson, M. E., Halawa, O. I., Tonsfeldt, K. J., Maxwell, C. A., Hammack, N., Mist, S., ... Heinricher, M. (2016). A possible neural mechanism for photosensitivity in chronic pain. Pain, 157(4), 868-878. https://doi.org/10.1097/j.pain.0000000000000450

A possible neural mechanism for photosensitivity in chronic pain. / Martenson, Melissa E.; Halawa, Omar I.; Tonsfeldt, Karen J.; Maxwell, Charlene A.; Hammack, Nora; Mist, Scott; Pennesi, Mark; Bennett, Robert (Rob); Mauer, Kim M.; Jones, Kim; Heinricher, Mary.

In: Pain, Vol. 157, No. 4, 01.04.2016, p. 868-878.

Research output: Contribution to journalArticle

Martenson, ME, Halawa, OI, Tonsfeldt, KJ, Maxwell, CA, Hammack, N, Mist, S, Pennesi, M, Bennett, RR, Mauer, KM, Jones, K & Heinricher, M 2016, 'A possible neural mechanism for photosensitivity in chronic pain', Pain, vol. 157, no. 4, pp. 868-878. https://doi.org/10.1097/j.pain.0000000000000450
Martenson ME, Halawa OI, Tonsfeldt KJ, Maxwell CA, Hammack N, Mist S et al. A possible neural mechanism for photosensitivity in chronic pain. Pain. 2016 Apr 1;157(4):868-878. https://doi.org/10.1097/j.pain.0000000000000450
Martenson, Melissa E. ; Halawa, Omar I. ; Tonsfeldt, Karen J. ; Maxwell, Charlene A. ; Hammack, Nora ; Mist, Scott ; Pennesi, Mark ; Bennett, Robert (Rob) ; Mauer, Kim M. ; Jones, Kim ; Heinricher, Mary. / A possible neural mechanism for photosensitivity in chronic pain. In: Pain. 2016 ; Vol. 157, No. 4. pp. 868-878.
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