Abstract
The purpose of this study was to determine whether any definite change in the brain development could be produced by the difference amounts of mastication. All teeth in the unilateral mandible of Wistar rats were enucleated at 2 weeks after birth and histological changes in the brain were examined at 4 and 8 weeks after birth.
In 4 week old rats, the number of pyramidal cells in the contralateral cerebral cortex of the no teeth side were much less than those of the ipsilateral side. However in 8 week old rats, there was no difference. In Hebb and Williams' maze test, Wistar rats weaned at 20 days of age were divided into two groups. Group 1 was fed on pellets, while Group 2 was fed on powder. At 4 and 8 weeks after birth, both groups were used or a Hebb and Williams' maze test.
In 8 week old rats, the total error score of the pellet group was less than that in the powder group. However in 4 week old rats, there was no difference in the total error score between the groups. From these results, it is deduced oral afferent impulses may stimulate the development of the brain in the animals chewing on the hard diet.
