Study of adaptability to oral environmental changes from brain plasticity perspective

9名受试者（平均年龄28.7岁）在左颌咀嚼口香糖时接受了功能磁共振成像检查，上颌左犬齿舌区有或没有树脂帽。本研究中使用的fMRI采集方案已在我们的试点研究中进行了优化。在涂树脂帽前、涂后和涂后30min分别进行功能磁共振成像（fMRI）。在每种情况下，9名受试者中有6人被要求咀嚼下颌左侧的蜡立方，以确定咀嚼效率。使用SPM2 （Statistical Parametric Mapping 2）分析fMRI数据，以确定脑活动的差异（未经校正的p=0.001，范围阈值=20体素）。在左侧咀嚼口香糖时，使用树脂帽后，双侧小脑后叶和右侧边缘上回近端比使用树脂帽前更活跃。小脑的激活可能反映了“运动学习”过程中小脑的活动。左侧咀嚼口香糖时，树脂帽敷后30min右侧小脑后叶活性低于敷后即刻。这一结果可能说明左咀嚼肌的运动学习和对带区帽左咀嚼口香糖的适应是有成就的。与咀嚼效率呈负相关的脑区为双侧中央后回、左侧中央前回、右侧扣带回、右侧颞上回、右侧小脑后叶和右侧小脑前叶。上述结果提示，树脂帽应用后立即激活右侧小脑后叶和前叶实现左侧咀嚼肌运动学习，以弥补咀嚼效率下降的缺陷；树脂帽应用后30min，随着咀嚼效率的提高和运动学习的实现，右侧小脑后叶和前叶的激活程度有所降低。

Nine subjects (mean age 28.7) underwent fMRI during chewing gum on the left side of jaw, with and without a resin cap on the lingual region of the maxillary left canine. fMRI acquisition protocol used in the present study has been optimised in our pilot study. fMRI was performed before, immediately after and 30min after applying resin cap. Six out of nine subjects were asked to masticate a wax cube on the left side of jaw in each condition to determine masticatory efficiency. fMRI data were analyzed with SPM2 (Statistical Parametric Mapping 2) to determine differences of brain activity (p=0.001 uncorrected, extent threshold=20voxels).During left side gum chewing, bilateral cerebellar posterior lobe and the proximal part of right supramarginal gyrus were more activated immediately after applying resin cap than before applying it. The activation of cerebellum might show the activity of cerebellum during "motor learning". During left side gum chewing, right cerebellar posterior lobe were less activated 30min after applying resin cap than immediately after applying it. This result might show that the motor learning of left masticatory muscles and the adaptation to left gum chewing with regin cap were achievement.The brain regions showing negative correlation to masticatory efficiency were bilateral postcentral gyrus, left precentral gyrus, right cingulate gyrus, right superior temporal gyrus, right cerebellar posterior lobe and right cerebellar anterior lobe. These findings suggest that right cerebellar posterior and anterior lobe were activated to achieve motor learning of left masticatory muscles to remedy reduced masticatory efficiency immediately after applying resin cap, and were less activated with the improvement of masticatory efficiency and achievement of motor learning 30min after applying resin cap.