title: Pain dynamics observed by functional magnetic resonance imaging: differential regression analysis technique.
abstract: OBJECTIVE
  To observe the dynamic responses of the cortical areas related to the pain processing by using the differential regression analysis (DRA) technique in functional magnetic resonance imaging (fMRI) and investigation of pain mechanisms.
  
  
  METHODS
  For pain studies, thermal stimulation was applied by immersing the index finger into a hot bath of water with a temperature of 50-52 degrees C. Motor (finger tapping) and visual (flickering light) stimulation experiments were conducted to elucidate the physiological differences between the simple sensory tasks and pain tasks. To obtain dynamic responses, T values (regression analysis) were sequentially estimated by using a series of shifted differential window functions (narrow width).
  
  
  RESULTS
  By using the DRA technique, well-defined prompt responses were observed for both motor and visual stimuli. On the other hand, in the pain experiment, a set of sequentially varying responses was observed for the thalamus (Thal), the dorsal anterior cingulate cortex (dACC), the caudal ACC (cACC), and the rostral ACC (rACC). This time-dependent response suggests the dynamics of pain signal processing in cortical areas.
  
  
  CONCLUSIONS
  The results support the hypothesis that the activated areas are similar to the previously reported pain processing areas; however, new sequential responses were observed, suggesting that the technique may reveal dynamics of pain perception and their pathway, important elements in understanding the mechanism of pain. The DRA technique can provide a new opportunity for many spatiotemporal analyses, for example, the physiologically complex and little-studied physiological phenomena, such as pain dynamics.
authors.affiliation: Department of Radiological Sciences, University of California, Irvine, California 92697, USA. zcho@uci.edu
authors.forename: Zang-Hee
authors.initials: ZH
authors.lastname: Cho
authors.forename: Young-Don
authors.initials: YD
authors.lastname: Son
authors.forename: Chang-Ki
authors.initials: CK
authors.lastname: Kang
authors.forename: Jae-Yong
authors.initials: JY
authors.lastname: Han
authors.forename: Edward K
authors.initials: EK
authors.lastname: Wong
authors.forename: Sun-Joon
authors.initials: SJ
authors.lastname: Bai
mesh_terms: D002540:Cerebral Cortex / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009043:Motor Activity / Q000502:physiology; D009434:Neural Pathways / Q000502:physiology; D009619:Nociceptors / Q000502:physiology; D010146:Pain / Q000503:physiopathology*; D010775:Photic Stimulation; D012044:Regression Analysis; D013788:Thalamus / Q000502:physiology