Abstract
We have been focusing on research of the function of human prefrontal cortex, in order to develop methods that can maintain and/or improve cognitive functions as well as quality of life. The prefrontal cortex is known to have an important cognitive function named executive function which plays important roles in making a future plan, decision making, control for behaviors, etc. In general, people feel decline of their cognitive functions by themselves after middle age. However, in fact, the functions of the prefrontal cortex decline linearly from age 20. The recent investigations of cognitive neuroscience show beneficial effects by cognitive trainings to prevent such age related decline of cognitive functions. Particularly, the working memory training is the one can improve non-trained prefrontal functions and induce plasticity for brain structures of the prefrontal cortex. Previously, we measured brain activity during movements of mouth, tongue, or rip by functional MRI. We found only the sensori-motor area of the bilateral cortices was activated, and no activation in the prefrontal cortex. Our results combined with the fact that mastication does not require working memory function lead a conclusion that one cannot improve cognitive functions only by mastication.
