The FMRI Study On The Human Cerebellum Involving Somatosensory Acquisition And Discrimination

Objective: To study the human cerebellum involving somatosensory acquisition and discrimination processing with functional magnetic image (fMRI), to reveal the integrative links of the brain regions, and to investigate the neuro-anatomical mechanism.Materials and Methods: A total of 12 healthy subjects, 7 male, 5 female, all right-handed, ranging in age from 21 to 33 years (average 27.3 years) from the Zhejiang University participated in the study. Consent was obtained from each subject that underwent imaging and psychophysical testing procedures approved by the Zhejiang University Human Subjects Review Committee. Each subject was given a detailed description of the experimental design such that they were fully aware of the duration and intensity of cutaneous stimulation to be endured, and were informed that they were free to withdraw from the study at any time. Prior to final entry into the study, test stimuli (both cold and hot) were applied to each subject to ensure that the stimuli were tolerable.All subjects were imaged on a conventional GE Signa 1.5 T MRI system. Eachsubject lay in a supine position on the MRI table stretching their hands, and their head was stabilized in a standard quadrature headcoil with a soft pillow and foam padding. Imaging parametersAnatomical images: FSE sequence T₁WI, data were obtained from thickness 5 mm, spacing lmm, axial slices parallel to AC-PC line, total 22 slices covering the whole brain.Functional images were obtained with a GE-EPI sequence T₂*WI, the same slice to the anatomical images, 120/slice. Functional activation maps were superimposed onto high resolution T₁-weighted anatomical images finally.3D scanning: FSPGR sequence was applied, the duration was 13'39". Experimental protocol and stimuliThe experimental protocol was block design, all subjects underwent a scanning session which consisted of two functional experiments: task one was a warm-tactile experiment (warm water in the 50ml-beaker), task two was a cool-tactile experiment (ice in the 50ml-beaker). The stimulation duration was 30 seconds, and the interval was 30 seconds, the total time was 372 seconds.Prior to each stimulation experiment, subjects were instructed to attend to their perception during the experiment such that the overall intensity of perception could be obtained for the entire scanning sequence. All stimuli were delivered to the thenar eminence of the left hand via a bottom of 50ml-beaker with a stimulation surface area of 3×3 cm². The stimulation was consistently applied to all subjects such that the beaker was resting on the thenar eminence and that subjects did not report any additional pressure exerted by the beaker other than light contact with its surface. Functional imaging experiments were separated by an interval of 5-10 min to allow for acclimatization of the skin to room temperature.All data were tranfered to the work stations, and analyzied by AFNI (Analysis of Functional Neurolmages), acquired the coordinate and volume of each activated brain region finally. According to the related references,the activation was defined bythreshold=3.302, P<5.0×10 ^-5. r≥0.20 in this study.SPSS 10.0 (Statistical Package for the Social Science) was applied. All data were tested by t-test and ANOVA.Results:1, During the task one, functional imaging in 12 healthy subjects yielded the consistently task-related activations were the right dentate 8/12, both of dentates 4/12, but the left was smaller than the right significantly (P<0.05); both of prefrontal gyms 12/12, no significance between two sides (P>0.05); both of posterior cingulates 12/12, no significance between two sides (P>0.05); the right post central gyms 7/12, both of post central gyms 5/12, but the left was smaller than the right significantly (P<0.05).2,During the task two, functional imaging in 12 healthy subjects yielded the consistently task-related activations were the right dentate 9/12, both of dentates 3/12, but the left was smaller than the right significantly (P<0.05); both of prefrontal gyms 12/12, no significan...