Adaption of the central masticatory pattern to the biomechanical properties of food

We propose that mastication is the result of the interaction of an intrinsic rhythmical pattern of neural commands and sensory feedback generated by the interaction of the effector system (muscles, bones, joints, teeth, tongue, lips and cheeks) with food. The main sources of variability in the pattern of human masticatory cycles are the subjects themselves, their age, the type of food being eaten and the position of the cycle within a series of movements. The intrinsic rhythmical pattern of mastication is generated by an assembly of neurons, a Central Pattern Generator (CPG), located at the ponto-bulbar junction of the brainstem. This simple neural program is modified by inputs that descend from higher centres of the brain and by feedback from sensory receptors. We describe the features of the masticatory CPG together with the interaction between the CPG and inputs from muscle spindles and periodontal pressoreceptors, which have especially powerful effects on movement parameters.