Chewing effects on intelligent activities in the elderly

包括预防老年痴呆在内的老年人保健是日本老龄化社会面临的关键问题之一。目前人们关注的焦点是老年人咀嚼对认知等高级脑功能的影响。在这项研究中，我们使用功能性磁共振成像（fMRI）来评估衰老对年轻人（19-26岁）、中年人（42-55岁）和老年人（65-73岁）咀嚼相关的大脑区域活动的影响。在有节奏咀嚼口香糖和休息（不咀嚼）的循环中，我们发现，在所有受试者中，咀嚼导致感觉运动皮层、小脑、丘脑、辅助运动区和脑岛的双侧BOLD信号增加，而右侧前额叶区域的单侧BOLD信号增加。在前三个区域，信号的增加以年龄依赖的方式减弱，而在右前额叶区域，相反的情况被看到。其余两个区域在年龄上没有显著差异。这些发现表明，咀嚼可能会刺激大脑皮层中与功能性记忆相关的区域。此外，在记忆测试的图像编码过程中，咀嚼引起海马（记忆形成不可或缺的大脑区域）BOLD信号的显著增加，这表明咀嚼参与了海马网络系统。此外，长期佩戴假牙的老年受试者在佩戴新全口义齿两周后，在图像编码时海马BOLD信号值升高。此外，在图像编码过程中，咀嚼引起的海马BOLD信号的增加明显高于不咀嚼的海马，海马被认为是大脑中记忆形成不可或缺的区域，这意味着咀嚼参与了海马网络系统。此外，未佩戴全口义齿的老年受试者在佩戴全口义齿两周后，在图像编码时海马BOLD信号值升高，受试者在记忆测试中得分更高。这些结果表明，咀嚼功能在维持和/或恢复老年人的学习和记忆中起着至关重要的作用。少

Health care of the elderly including prevention of senile dementia is one of the key issues facing Japanese aged society. Much attention is currently focused on chewing effects in the elderly on higher brain function such as cognition. In this study, we used functional magnetic resonance imaging (fMRI) to assess the effect of aging on brain regional activity associated with chewing in young adult (19-26 yrs), middle-aged (42-55 yrs), and aged (65-73 yrs) healthy humans.Using fMRI during cycles of rhythmic gum-chewing and rest (no chewing), we found that, in all subjects, chewing resulted in a bilateral increase in the BOLD signals in the sensorimotor cortex, cerebellum, thalamus, supplementary motor area, and insula, and a unilateral increase in the right prefrontal area. In the first three regions, the signal increases were attenuated in an age-dependent manner, whereas, in the right prefrontal area, the converse was seen. The remaining two regions showed no significant differences wi … More th ages. These findings suggest that chewing may stimulate functionally memory-related regions in the cerebral cortex.Furthermore, chewing caused a significantly higher increase of the BOLD signals in the hippocampus, an indispensable brain region for memory formation, during picture encoding in the memory test, in comparison with those without chewing, implying involvement of chewing in the hippocampal network system. Furthermore, two weeks after wearing the new full proper dentures of the aged subjects whose denture was improper for long time, higher value of the hippocampal BOLD signals were caused during picture encoding.In addition, during picture encoding, chewing caused a significantly higher increase of the BOLD signals in the hippocampus, being believed to play an indispensable brain region for memory formation, in comparison with those without chewing, implying involvement of chewing in the hippocampal network system. Furthermore, two weeks after wearing the full dentures of the aged subjects who had never worn them, higher value of the hippocampal BOLD signals were caused during picture encoding, and the subject got higher scores in the memory test.These results indicate that masticatory function plays a crucial role in maintaining and/or recovering learning and memory in the elderly. Less