title: Spinal cord response to stepwise and block presentation of thermal stimuli: a functional MRI study.
abstract: OBJECTIVE
  To examine the characteristics of the spinal cord and brainstem blood oxygenation level-dependent (BOLD) responses to peripheral stimulation in which the temperature is raised in a stepwise fashion, in order to enhance receptor responses, compared to a block design.
  
  
  METHODS
  Functional magnetic resonance imaging (fMRI) studies of the spinal cord and brainstem were carried out in 14 healthy volunteers at 3T. Thermal sensory stimuli were applied to the right hand in a block-design paradigm, and in a stepwise paradigm to the same peak temperature. Data were analyzed by means of a general linear model, region of interest analyses, and by structural equation modeling.
  
  
  RESULTS
  Results demonstrated BOLD responses in a number of consistent regions between the two paradigms as well as significant differences (P < .001) in the locations and magnitudes of some responses. Specifically, the BOLD response in the dorsal horn was significantly higher in the stepwise compared to the block condition (P < .001). However, more significant connections (T >2) between regions were observed in the block condition.
  
  
  CONCLUSIONS
  Results from this study demonstrate the means to design thermal sensory paradigms to probe components of sensory processing in the brainstem and spinal cord.
authors.affiliation: Centre for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada.
authors.forename: Rachael L
authors.initials: RL
authors.lastname: Bosma
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Stroman
mesh_terms: D000293:Adolescent; D000328:Adult; D001933:Brain Stem / Q000502:physiology*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006358:Hot Temperature; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology*; D010812:Physical Stimulation / Q000379:methods; D013116:Spinal Cord / Q000502:physiology*; D013697:Thermosensing / Q000502:physiology*; D055815:Young Adult
keywords: BOLD; brainstem; functional MRI; human; spinal cord; structural equation modeling