title: The role of the Supplementary Motor Area (SMA) in the execution of primary motor activities in brain tumor patients: functional MRI detection of time-resolved differences in the hemodynamic response.
abstract: BACKGROUND
  Interpreting volume of activation maps of brain tumor patients remains difficult using blood oxygenation-level dependent (BOLD) functional magnetic resonance imaging (fMRI) methods. A time-resolved fMRI may offer an informative strategy for investigating the possibility of functional reorganization by elucidating temporal variations in the activation of cortical structures . The aim of this study is to use time-resolved fMRI to investigate potential alterations in the spatially-varying and time-dependent hemodynamic response function within the supplementary motor area (SMA) and primary motor cortex (PMC) in the presence of an adjacent brain tumor, relative to normal control subjects.
  
  
  METHODS
  Fifteen patients and eight healthy volunteers were recruited. By utilizing a brief motor paradigm that exerts a differential effect on the activation of these structures, latency differences in the hemodynamic responses of such areas may be sensitively investigated. The present study determines the utility of this approach in brain tumor patients by examining the time to peak of the BOLD hemodynamic response within the SMA and PMC.
  
  
  RESULTS
  In patients with glial tumors involving the PMC, the activation of the SMA was delayed and approached that of the PMC with time-to-peak difference between the PMC and SMA averaging 0.2 s. This delay in SMA activation was seen in all patients with glial tumors involving the PMC.
  
  
  CONCLUSIONS
  The results suggest that in patients with high-grade brain tumors invading the PMC , the SMA may assume a greater role in the execution of primary motor activities, in addition to its role in executive motor planning.
authors.affiliation: Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA. peckk@mskcc.org
authors.forename: Kyung K
authors.initials: KK
authors.lastname: Peck
authors.forename: Michelle S
authors.initials: MS
authors.lastname: Bradbury
authors.forename: Bob L
authors.initials: BL
authors.lastname: Hou
authors.forename: Nicole Petrovich
authors.initials: NP
authors.lastname: Brennan
authors.forename: Andrei I
authors.initials: AI
authors.lastname: Holodny