KATO Tomohiro Gifu University, School of Medicine, Associate professor, 医学部附属病院, 助教授 (40224521)
KANEMATSU Masayuki Gifu University, School of Medicine, Associate professor, 医学部附属病院, 助教授 (40252134)
FUJITA Masafumi Gifu University, Graduate School of Medicine, Assistant professor, 大学院・医学研究科, 講師 (50021449)
FUJIWARA Shu Asahi University, Department of Dentistry, Associate professor, 歯学部, 助教授 (50229069)
KUBO Kin-ya Asahi University, Department of Dentistry, Assistant professor, 歯学部, 講師 (00329492)
|Budget Amount *help
¥14,700,000 (Direct Cost : ¥14,700,000)
Fiscal Year 2004 : ¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 2003 : ¥12,700,000 (Direct Cost : ¥12,700,000)
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
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