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Investigation of the relative efficacy of tasks and stimuli for activation of motor and somatosensory cortex by fMRI: Comparison of per-cent signal change, extent and laterality measurements
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SENSORIMOTOR
Investigation of the Relative Efficacy of Tasks and Stimuli for Activation of Motor and Somatosensory Cortex by fMRI: Comparison of Per-cent Signal Change, Extent and Laterality Measurements Arshad Zaman*f,
Krish Shy&M,
N. Roberts*?
*Magnetic Resonance & Image Analysis Research Centre (MARIARC),
University of Liverpool, UK
t Walton Centre of Neurology and Neurosurgery (WCNN), Liverpool, UK *Department of Vision Sciences, University of Aston, Birmingham, UK The purpose of this study was to investigate inter-subject variability in the fMFU response of motor and somatosensory cortex due to a range of motor tasks and sensory stimuli. Method MB data were acquired for ten healthy subjects (7 male and 3 female; mean age 29.9 years, range 24 to 40 years) on a 1.5 T LX/Nvi system (General Electric, Milwaukee, USA). Twenty two contiguous axial T2* weighted gradient-echo EPI slices (TE 4Oms, TR 3s, flip angle 90”. matrix 64*64, Field of View 24 cm, slice thickness 5mm) were prescribed through the brain. A two condition boxcar design was used in which conditions alternated every 15 seconds, for a total of five minutes. Visual instructions were generated by using HyperCard software on a Macintosh computer, and were presented to the subject using an Epslon LMP7300 projector via a backprojection screen. Subjects performed 5 motor tasks, namely, (i) tongue curling, (ii) lips pursing, (iii) finger curling (bilateral), (iv) hand squeeze (right) and toe curling (bilateral) and also (vi) imagination of fingers lengthening (right). A compressed air &vice developed in house with digitally controlled valves was used to provide an air-puff stimulus to (i) foot (right instep), (ii) lower leg (right calf), (iii) hand (right palm), (iv) lips and (v) forehead. Data were analysed with SPM99 software (Wellcome Functional Imaging Laboratory) which included motion correction, spatial normalisation and smoothing with a 6 mm Gaussian kernel. Single subject data were co-registered with and displayed on a 3D Tl-weighted MB image obtained for each subject. Group analyses were also performed.
Group analysis confirmed the presence of motor and sensory-motor homunculi along the pte-central and post-central gyms, respectively, with lower extremities represented on the superior-medial aspect and the head represented at the inferior-lateral extreme of the gyrus. Au motor tasks and the imagination task produced significant activation in primary motor cortex, SMA and cerebellum in single subject analyses. The air-puff stimulus produced significant activation in foot, hand lips and forehead but not lower leg. The magnitude of the BOLD signal change and the extent of activations was larger for motor tasks than for the air-puff stimuli. Furthermore, the BOLD response of motor cortex was inherently more bilateral than that in sensory-motor cortex. Condusion The comparison of single subject and group analyses presented in this study provides data relevant for establishing pre-surgical procedures to be used in individual patients for defining possible resection margins for lesions in motor and sensory-motor cortex.
s1284
SENSORIMOTOR
Investigation of the Relative Efficacy of Tasks and Stimuli for Activation of Motor and Somatosensory Cortex by fMRI: Comparison of Per-cent Signal Change, Extent and Laterality Measurements Arshad Zaman*f,
Krish Shy&M,
N. Roberts*?
*Magnetic Resonance & Image Analysis Research Centre (MARIARC),
University of Liverpool, UK
t Walton Centre of Neurology and Neurosurgery (WCNN), Liverpool, UK *Department of Vision Sciences, University of Aston, Birmingham, UK The purpose of this study was to investigate inter-subject variability in the fMFU response of motor and somatosensory cortex due to a range of motor tasks and sensory stimuli. Method MB data were acquired for ten healthy subjects (7 male and 3 female; mean age 29.9 years, range 24 to 40 years) on a 1.5 T LX/Nvi system (General Electric, Milwaukee, USA). Twenty two contiguous axial T2* weighted gradient-echo EPI slices (TE 4Oms, TR 3s, flip angle 90”. matrix 64*64, Field of View 24 cm, slice thickness 5mm) were prescribed through the brain. A two condition boxcar design was used in which conditions alternated every 15 seconds, for a total of five minutes. Visual instructions were generated by using HyperCard software on a Macintosh computer, and were presented to the subject using an Epslon LMP7300 projector via a backprojection screen. Subjects performed 5 motor tasks, namely, (i) tongue curling, (ii) lips pursing, (iii) finger curling (bilateral), (iv) hand squeeze (right) and toe curling (bilateral) and also (vi) imagination of fingers lengthening (right). A compressed air &vice developed in house with digitally controlled valves was used to provide an air-puff stimulus to (i) foot (right instep), (ii) lower leg (right calf), (iii) hand (right palm), (iv) lips and (v) forehead. Data were analysed with SPM99 software (Wellcome Functional Imaging Laboratory) which included motion correction, spatial normalisation and smoothing with a 6 mm Gaussian kernel. Single subject data were co-registered with and displayed on a 3D Tl-weighted MB image obtained for each subject. Group analyses were also performed.
Group analysis confirmed the presence of motor and sensory-motor homunculi along the pte-central and post-central gyms, respectively, with lower extremities represented on the superior-medial aspect and the head represented at the inferior-lateral extreme of the gyrus. Au motor tasks and the imagination task produced significant activation in primary motor cortex, SMA and cerebellum in single subject analyses. The air-puff stimulus produced significant activation in foot, hand lips and forehead but not lower leg. The magnitude of the BOLD signal change and the extent of activations was larger for motor tasks than for the air-puff stimuli. Furthermore, the BOLD response of motor cortex was inherently more bilateral than that in sensory-motor cortex. Condusion The comparison of single subject and group analyses presented in this study provides data relevant for establishing pre-surgical procedures to be used in individual patients for defining possible resection margins for lesions in motor and sensory-motor cortex.
s1284