Study of adaptability to oral environmental changes from brain plasticity perspective

9名受试者（平均年龄28.7岁）在咀嚼口香糖的过程中进行了功能性磁共振成像的左侧颌骨，有和没有树脂帽的舌侧区域的上颌左犬齿。本研究中使用的fMRI采集协议已在我们的试点研究中进行了优化。分别于戴帽前、戴帽后即刻及戴帽后30 min进行fMRI检查。9名受试者中的6名被要求在每种情况下咀嚼下颌左侧的蜡块以确定咀嚼效率。采用SPM 2软件对fMRI数据进行分析（统计参数映射2）以确定大脑活动的差异（p=0.001未校正，范围阈值= 20体素）。在左侧咀嚼口香糖期间，双侧小脑后叶和右侧缘上回近端在应用树脂帽后即刻较应用前激活，小脑的激活可能反映了小脑在应用树脂帽时的活动。运动学习”。左侧咀嚼口香糖时，右侧小脑后叶在戴树脂帽后30 min较戴树脂帽后即刻活动减少，提示左侧咀嚼肌的运动学习和对戴区域帽咀嚼口香糖的适应是成功的，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、右侧扣带回、右侧中央后回、右侧中央前回、右侧中央后回右侧上级颞回、右侧小脑后叶和右侧小脑前叶。结果提示，戴帽后即刻，右侧小脑后叶和前叶被激活，完成左侧咀嚼肌的运动学习，以弥补咀嚼效率的降低;戴帽后30 min，随着咀嚼效率的提高和运动学习的完成，右侧小脑后叶和前叶的激活程度降低。

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.