SATO Sadao Kanagawa Dental College, Dentistry, Professor (00084799)
UEMATSU Hiroshi Tokyo Medical and Dental University, Dentistry, Professor (80100957)
KANEMATSU Masayuki Gifu University Hospital, Faculty of Medicine, Associate professor (40252134)
WATANABE Kazuko Seijo University, Rehabilitation, Professor (40158621)
|Budget Amount *help
¥40,430,000 (Direct Cost: ¥31,100,000、Indirect Cost: ¥9,330,000)
Fiscal Year 2007: ¥7,280,000 (Direct Cost: ¥5,600,000、Indirect Cost: ¥1,680,000)
Fiscal Year 2006: ¥33,150,000 (Direct Cost: ¥25,500,000、Indirect Cost: ¥7,650,000)
The goal of this project is to elucidate the crosstalk mechanism(s) between the masticatory organs and the higher brain including the cerebral and the hippocampus. Especially, we focused on the preventive effect of Chewing stimulus on memory processes in aged humans, using the functional magnetic resonance imaging (fMRI) technique and the behavioral method. In the first experiment, using fMRI during rhythmic gum-chewing and no chewing, we examined the effect of aging on brain regional activity during chewing in young adult, middle-aged, and aged intact humans. 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 with ages.
We did another fMRI experiment, in which we examined the effect of chewing on the hippocampal activities, by employing a task using photographs containing spatial cognitive function. As a result, the hippocampus in young subjects was strongly activated, but no significant difference was seen between before and after chewing. In contrast, activation in the elderly was quite small in comparison with the young subjects. However, the activation area and the intensity of fMRI signals increased by chewing. Furthermore, according to the results from the recall test, aged subjects showed a significant increase in memory acquisition after chewing.
Furthermore, increases in hippocampal activities and memory acquisition were recognized after denture wearing. These results strongly suggest that, in the elderly, chewing causes an enhancement and/or maintaining in hippocampus-dependent cognitive memory.