Investigation of human frontal cortex under noxious thermal stimulation of temporo-mandibular joint using functional near infrared spectroscopy

Amarnath Yennu, Rohit Rawat, Michael T. Manry, Robert Gatchel, Hanli Liu

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

1 Scopus citations


According to American Academy of Orofacial Pain, 75% of the U.S. population experiences painful symptoms of temporo-mandibular joint and muscle disorder (TMJMD) during their lifetime. Thus, objective assessment of pain is crucial for efficient pain management. We used near infrared spectroscopy (NIRS) as a tool to explore hemodynamic responses in the frontal cortex to noxious thermal stimulation of temporomadibular joint (TMJ). NIRS experiments were performed on 9 healthy volunteers under both low pain stimulation (LPS) and high pain stimulation (HPS), using a temperature-controlled thermal stimulator. To induce thermal pain, a 16X16 mm2 thermode was strapped onto the right TMJ of each subject. Initially, subjects were asked to rate perceived pain on a scale of 0 to 10 for the temperatures from 41°C to 47°C. For the NIRS measurement, two magnitudes of temperatures, one rated as 3 and another rated as 7, were chosen as LPS and HPS, respectively. By analyzing the temporal profiles of changes in oxy-hemoglobin concentration (HbO) using cluster-based statistical tests, we were able to identify several regions of interest (ROI), (e.g., secondary somatosensory cortex and prefrontal cortex), where significant differences (p<0.05) between HbO responses to LPS and HPS are shown. In order to classify these two levels of pain, a neural-network-based classification algorithm was used. With leave-one-out cross validation from 9 subjects, the two levels of pain were identified with 100% mean sensitivity, 98% mean specificity and 99% mean accuracy to high pain. From the receiver operating characteristics curve, 0.99 mean area under curve was observed.

Original languageEnglish
Title of host publicationOptical Tomography and Spectroscopy of Tissue X
StatePublished - 2013
EventOptical Tomography and Spectroscopy of Tissue X - San Francisco, CA, United States
Duration: 3 Feb 20136 Feb 2013

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
ISSN (Print)1605-7422


OtherOptical Tomography and Spectroscopy of Tissue X
Country/TerritoryUnited States
CitySan Francisco, CA


  • Hemodynamic responce
  • NIRS
  • Neural network based classification
  • Temporo-mandibular joint
  • Thermal stimulation


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