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BOLD, CBF, and CMRO2 in the human primary motor cortex
NeuroImage
11, Number
52000,
Part 2 of 2 Parts 10
E-+1@
PHYSIOLOGY
BOLD, CBF, and CMR02 in the Human Primary Motor Cortex Jeffrey Atkinson*tS, Rick HogeBq/, Bradford Gill*?*, Christian Abbas F. Sadikot*$& G. Bruce Pike*?+ *McConnell
Duval*tS,
Brain Imaging Centre
TMcGill University SMontreal, Quebec, Canada $NMR Center ‘Massachusetts General Hospital IICharlestown, Massachusetts, USA Introduction: Previous work from our laboratory has demonstrated the relationship between BOLD, CBF, and CMROl in the human visual system. This work was important not only in improving the understanding of physiological basis of the BOLD signal, but also in establishing BOLD fMRI as a robust brain mapping tool. The degree to which the relationship between BOLD and CBF might vary with brain region, neuronal subpopulation, or specfic task demand is still not known. We sought to establish the relationship between these measures in areas activated with a simple motor task. Methods: Six healthy right-handed volunteers were studied using a 1.5 T Siemens Vision MR system. Subjects performed pronationsupination movements paced by a visual stimulus at frequencies ranging from 0.25 to 1.5 Hz over three scanning sessions. The amplitude and frequency of these movements was recorded using a laser displacement detector. In the first two sessions subjects performed movements at 0.25, 0.5, 0.75, and 1 Hz during the 2nd, 3rd, and 4th minutes of a separate six minute scanning runs. BOLD and perfusion data was acquired using a locally developed, single-slice, interleaved BOLD/FAIR pusle sequence. During the third scanning session subjects performed movments at 0.25, 1 and 1.5 Hz and inhaled three different concentrations of CO, (max. 5%) during the 2nd, 3rd, and 4th minutes of six separate six minute scanning runs. Data for this session was acquired using a locally developed, three slice, interleaved BOLD/FAIR pulse sequence. CBF and BOLD percent changes were calculated for each run and averaged over subjects for the motor task and the hypercapnia. Preliminary CMRO, calculations were made using a biophysical model.
Statistically significant activation was found in the contralateral primary motor cortex, SMA, and, ipsilateral cerebellum, for individual subjects. In the primary motor cortex percent change in BOLD signal increased with increasing motor task performance frequency and were linearly related to the FAIR signal percent changes increases. Similarly. for inhaled CO,, BOLD and CBF percent changes were linearly related. Conclusions: In the primary motor cortex BOLD responses vary as a function of motor frequency and show a linear relationship to changes in CBF. These results are consistent with those in the visual cortex and increase confidence in the general applicability of BOLD fMR1 as a qualitative and quantitative brain mapping tool.
S803
11, Number
52000,
Part 2 of 2 Parts 10
E-+1@
PHYSIOLOGY
BOLD, CBF, and CMR02 in the Human Primary Motor Cortex Jeffrey Atkinson*tS, Rick HogeBq/, Bradford Gill*?*, Christian Abbas F. Sadikot*$& G. Bruce Pike*?+ *McConnell
Duval*tS,
Brain Imaging Centre
TMcGill University SMontreal, Quebec, Canada $NMR Center ‘Massachusetts General Hospital IICharlestown, Massachusetts, USA Introduction: Previous work from our laboratory has demonstrated the relationship between BOLD, CBF, and CMROl in the human visual system. This work was important not only in improving the understanding of physiological basis of the BOLD signal, but also in establishing BOLD fMRI as a robust brain mapping tool. The degree to which the relationship between BOLD and CBF might vary with brain region, neuronal subpopulation, or specfic task demand is still not known. We sought to establish the relationship between these measures in areas activated with a simple motor task. Methods: Six healthy right-handed volunteers were studied using a 1.5 T Siemens Vision MR system. Subjects performed pronationsupination movements paced by a visual stimulus at frequencies ranging from 0.25 to 1.5 Hz over three scanning sessions. The amplitude and frequency of these movements was recorded using a laser displacement detector. In the first two sessions subjects performed movements at 0.25, 0.5, 0.75, and 1 Hz during the 2nd, 3rd, and 4th minutes of a separate six minute scanning runs. BOLD and perfusion data was acquired using a locally developed, single-slice, interleaved BOLD/FAIR pusle sequence. During the third scanning session subjects performed movments at 0.25, 1 and 1.5 Hz and inhaled three different concentrations of CO, (max. 5%) during the 2nd, 3rd, and 4th minutes of six separate six minute scanning runs. Data for this session was acquired using a locally developed, three slice, interleaved BOLD/FAIR pulse sequence. CBF and BOLD percent changes were calculated for each run and averaged over subjects for the motor task and the hypercapnia. Preliminary CMRO, calculations were made using a biophysical model.
Statistically significant activation was found in the contralateral primary motor cortex, SMA, and, ipsilateral cerebellum, for individual subjects. In the primary motor cortex percent change in BOLD signal increased with increasing motor task performance frequency and were linearly related to the FAIR signal percent changes increases. Similarly. for inhaled CO,, BOLD and CBF percent changes were linearly related. Conclusions: In the primary motor cortex BOLD responses vary as a function of motor frequency and show a linear relationship to changes in CBF. These results are consistent with those in the visual cortex and increase confidence in the general applicability of BOLD fMR1 as a qualitative and quantitative brain mapping tool.
S803