Cerebral activation related to the control of mastication during changes in food hardness.

To investigate the neural network involved in the control of mastication during changes in food hardness, we employed functional magnetic resonance imaging while 15 healthy subjects chewed gum whose hardness was changed by chewing. By comparing the areas activated when the hardness of the bolus varied widely with those seen when the hardness of the bolus had stabilized, we identified selective activations of the supplementary motor area, the dorsolateral prefrontal cortex, the superior temporal gyrus of the left hemisphere, and the premotor area and inferior parietal lobule of the right hemisphere. These findings indicate that these areas are probably related to processes linking sensory input and motor output involved in the change of hardness food during mastication.