title: Higher pain rating results in lower variability of somatosensory cortex activation by painful mechanical stimuli: An fMRI study.
abstract: OBJECTIVE
  The aim of this study was to find pain-related brain activity which corresponds to self-report pain ratings based on degree of response and repeatability.
  
  
  METHODS
  Three painful mechanical stimuli were applied to the right hands of 25 healthy volunteers using monofilaments (forces of 0.98N, 2.94N, and 5.88N). Simultaneously, brain activities were evaluated using functional MRI for a constant stimulus conducted three times in a session. In first assessment, the average percent signal change (PSC) of neuronal response was measured for each region of interest (ROI), secondary repeatability of PSC conducted three times over the session was evaluated for each ROI.
  
  
  RESULTS
  Although the average PSCs for trice stimuli conducted in one session increased in accordance with pain ratings in the somatosensory cortex (S1) and anterior cingulate cortex (ACC), there was a different response between S1 and ACC when subjects rated intense pain; a stable response in S1 against a variable response in ACC.
  
  
  CONCLUSIONS
  These results imply that there are different cognitive responses between sensory discrimination and affective component to constant painful stimulus each time.
  
  
  CONCLUSIONS
  Consistency of brain activity based on PSC may be an important biomarker which, along with its neuronal activity, gauges self-report pain ratings.
authors.affiliation: Multidisciplinary Pain Center, Aichi Medical University, Japan; Department of Rehabilitation, Nagoya University Hospital, Japan. Electronic address: hayashi.k@med.nagoya-u.ac.jp.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Hayashi
authors.affiliation: Multidisciplinary Pain Center, Aichi Medical University, Japan; Institute of Physical Fitness, Sports Medicine and Rehabilitation, Aichi Medical University, Japan.
authors.forename: Tatsunori
authors.initials: T
authors.lastname: Ikemoto
authors.affiliation: National Hospital Organization, Hizen Psychiatric Center, Japan.
authors.forename: Takefumi
authors.initials: T
authors.lastname: Ueno
authors.affiliation: Multidisciplinary Pain Center, Aichi Medical University, Japan.
authors.forename: Young-Chang P
authors.initials: YC
authors.lastname: Arai
authors.affiliation: Multidisciplinary Pain Center, Aichi Medical University, Japan; Institute of Physical Fitness, Sports Medicine and Rehabilitation, Aichi Medical University, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Shimo
authors.affiliation: Multidisciplinary Pain Center, Aichi Medical University, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Nishihara
authors.affiliation: Department of Physical and Occupational Therapy, Graduate School of Medicine, Nagoya University, Japan.
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Suzuki
authors.affiliation: Multidisciplinary Pain Center, Aichi Medical University, Japan; Institute of Physical Fitness, Sports Medicine and Rehabilitation, Aichi Medical University, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Ushida
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010146:Pain / Q000175:diagnosis* / Q000378:metabolism*; D010147:Pain Measurement / Q000379:methods*; D010812:Physical Stimulation / Q000009:adverse effects; D057566:Self Report; D013003:Somatosensory Cortex / Q000378:metabolism*; D055815:Young Adult
keywords: Brain activity; Pain perception; Pain rating; Repeatability