Abstract
It has been known that masticatory movement, especially during chewing, is controlled by the brain stem. However, as mastication is a sequential action from food intake to swallowing, the higher brain, such as the cerebral cortex and basal ganglia, is thought to be needed for the control of mastication. In the cerebral cortex, the cortical masticatory area (CMA), to which repetitive electrical stimulation induces rhythmic jaw movements like masticatory movements, may be involved in the control of mastication. In the rabbit, the CMA is divided into two parts, based on induced jaw movement patterns. One is the part of CMA in which a jaw movement pattern (T-pattern) similar to food-transporting movement in natural mastication is evoked by electrical stimulation. The other part of the CMA is more dorso-medially located, and another jaw movement pattern (C-pattern) similar to chewing movement can be induced. What is the functional difference between two parts of the CMA? When we investigated the cortico-striatal pathway from two parts of the CMA in the rabbit, while the ventral part of the putamen receives the input from both parts, the input from the T-pattern inducing CMA was broader than that from the C-pattern inducing CMA. Recently, we also found that there were two parts of the CMA in the guinea pig as in the rabbit, and the distribution of the terminals of the cortico-cortical projections from these parts was different. From these findings, it is suggested that two parts in the CMA have different effects not only on the brain stem but also on the neuronal network in the higher brain. [J Physiol Sci. 2007;57 Suppl:S13]
