Brain Function for Enjoying Meal-Study by Using Positron CT

首先，本研究利用FDG-PET定量分析下颌骨侧移过程中咀嚼肌和大脑的局部和整体活动。11名咀嚼功能正常的健康年轻男性志愿者参加了这项研究。每位受试者在肘静脉注射39.2 +/-5.2 MBq ^<18>的F-FDG。注射后，要求每位受试者以1.0 Hz的频率开始下颌骨左侧偏移，然后持续30分钟。结果表明，对侧翼状外侧肌和翼状内侧肌的平均sar明显高于双侧咬肌。各被试咀嚼肌功能过程中FDG积累量存在较大差异，且各被试的肌肉活动各有不同。然而，通过PET图像表征下颌骨功能过程中的脑活动是困难的。因此，功能磁共振成像（fMRI）也被用于分析咀嚼口香糖时的脑功能。在磁共振扫描仪（Siemens Magnetom Vision Plus, 1.5T）中，受试者（3名男性）戴着耳塞，仰卧位，被指示执行以下任务：咀嚼无味道和橙色味道的口香糖作为味觉刺激，观看橙色切割表面的投影图像和橙色马赛克作为视觉刺激。结合这些刺激，在四种情况下进行磁共振成像。结果表明，当味觉和视觉同时受到刺激时，顶叶和颞叶的活动要比不同时受到刺激时多。另一方面，橘子图像和被遮挡的图像作为视觉刺激，对有味觉刺激和没有味觉刺激的大脑活动差异没有影响。

At first, the study was designed to quantify the local and overall activity of masticatory muscles and the brain during lateral excursion of the mandible using FDG-PET. Eleven healthy young male volunteers who had normal masticatory function participated in the study. Each subject received an injection of 39.2 +/-5.2 MBq of ^<18>F-FDG into the cubital vein. Just after the injection, each subject was asked to start left lateral excursion of the mandible at 1.0 Hz and then continued for 30 min. As results, the mean SURs of contralateral lateral pterygoid and medial pterygoid muscles were significantly higher than those of the bilateral masseter muscles. There was large variation in the FDG accumulation of the masticatory muscles during function among subjects and muscle activities of each subject showed individual manner. However it was difficult to characterize the brain activities during mandibular function by PET images.Therefore functional magnetic resonance imaging (fMRI) was also applied to analyze the brain function during gum chewing. In the MR Scanner (Siemens Magnetom Vision Plus, 1.5T), subjects (three males) wearing earplugs in a supine position were instructed to perform the following task : chewing gum with no taste and orange taste as taste stimuli and watching the projected images of the cutting surface of an orange and an orange colored mosaic as visual stimuli. Combining these stimuli, MR imaging under four conditions were carried out. As results, much activities in the parietal and temporal lobes were observed when both of taste and visual stimuli were applied than when both were not. On the other hand, the image of an orange and the occluded image as visual stimuli had no effect on the difference between the brain activities with and without taste stimuli.