The Brain FMRI Research Induced By Contact Heat Stimulations

Objective:A and C fiber nociceptors can be excited when people receivedcontact heat stimulation(CHS) and this excitation may be reflected byfunctional magnetic resonance imaging(fMRI). So the aim of this study wasto observe the different fMRI characteristics in CHS with distincttemperatures in healthy people and to explore the pain related functionalnetwork. Depending on the fMRI result, we can evaluate the value ofCHS-fMRI during the research of brain functional connectivity.Methods:22healthy volunteers were recruited to take part in this study (12female,10male). During the acquisition of functional magneticresonance imaging(fMRI), the right dorsal forearm received twodifferent CHS in41and51degree respectively(41℃CHS-fMRI group and51℃CHS-fMRI group), so two groups of fMRI data were obtained for eachsubject. Visual analogue scale (VAS) was used to score the temperaturestimulation for each subject after test. The process of fMRI data wasperformed using spm8software package.The brain activation of group wasobtained by using one sample t test for the41℃CHS-fMRI group and51℃CHS-fMRI group separately. The difference between41℃CHS-fMRIgroup and51℃CHS-fMRI group was analyzed by paired-sample t-test.Thecorrelation between the change of blood oxygen level dependent(BOLD)caused by stimulation and VAS was also evaluated. Finally, SPSS was used toassess the difference of VAS between41℃CHS-fMRI group and 51℃CHS-fMRI group as well as their correlation coefficients(p<0.01).Result:1.These activated brain areas in41℃CHS-fMRI group with statisticalsignificance (P <0.001) included bilateral superior temporal gyrus(STG),contralateral transverse temporal gyrus, contralateral amygdala,bilateral insula, bilateral inferior frontal gyrus(IFG), contralateralhippocampus, bilateral putamen, contralateral supramarginal, ipsilateralpostcentral, ipsilateral inferior parietal lobule(IPL), ipsilateral middletemporal gyrus(MTG), bilateral cerebelum, bilateral middle cingulatecortex(MCC) and bilateral posterior cingulate cortex(PCC).These activated brain areas in51℃CHS-fMRI group with statisticalsignificance (P <0.001) included bilateral STG, bilateral amygdala,contralateral hippocampus, bilateral thalamus, contralateral putamen, bilateralinsula, bilateral IFG, bilateral cerebellum, contralateral postcentral,contralateral superior parietal lobule(SPL), bilateral MTG, bilateral precuneus,contralateral cuneus.Compared with41℃CHS-fMRI group, the51℃CHS-fMRI groupshowed higher brain activation in bilateral cerebellum, ipsilateral precuneus,contralateral insula, contralateral IFG, contralateral postcentral (p<0.005).2. In41℃CHS-fMRI group，there had no areas with significantcorrelation(p>0.01) between VAS and brain activation intensity. By the same,in51℃CHS-fMRI group the brain areas that showed significant correlation(p<0.01) between VAS and BOLD intensity are located in contralateral ACC,contralateral island of IFG, contralateral precentral（M2）and contralateralpremotor area（M1）.3. The score of VAS in51℃CHS-fMRI group was higher than 41℃CHS-fMRI group with statistical significance(P <0.01), and thecorrelation of the VAS betweentwo groups had a significant correlation(r=0.706) with statistical significance (P <0.01).Conclusions:1.CHS may become one of the ideal pain stimulation methods and alsofMRI become one of the usefully measures for the research of pain relatednetwork. It could demonstrate that there were a series of pain-related cerebralareas in the brain which consisted of pain-related networks with CHS-fMRI，and supported a viewpoint that pain belonged to a synaesthesia.2.Compared the results from both group, we can find the common brainactivated areas and specific areas for each group.These results suggest thatexistence of two central pathways activated by A and C fiber who havedifferent effect in perception of pain and have their brain networkresponsively.