Jaw sensorimotor control in healthy adults and effects of aging

Summary

The orofacial sensorimotor system is a unique system significantly distinguished from the spinal sensorimotor system. The jaw muscles are involved in mastication, swallowing and articulatory speech movements and their integration with respiration. These sensorimotor functions are vital for sustaining life and necessitate complex neuromuscular processing to provide for exquisite sensorimotor control of numerous orofacial muscles. The function of the jaw muscles in relation to sensorimotor control of these movements may be subject to aging-related declines. This review will focus on peripheral, brainstem and higher brain centre mechanisms involved in reflex regulation and sensorimotor coordination and control of jaw muscles in healthy adults. It will outline the limited literature bearing on age-related declines in jaw sensorimotor functions and control including reduced biting forces and increased risk of impaired chewing, speaking and swallowing. The mechanisms underlying these alterations include age-related degenerative changes within the peripheral neuromuscular system and in brain regions involved in the generation and control of jaw movements. In light of the vital role of jaw sensorimotor functions in sustaining life, normal aging involves compensatory mechanisms that utilize the neuroplastic capacity of the brain and the recruitment of additional brain regions involved in sensorimotor performance and closely associated functions (e.g., cognition and memory). However, these regions are themselves susceptible to detrimental age-related changes. Thus, better understanding of the peripheral and central mechanisms underlying age-related sensorimotor impairment is crucial for developing improved treatment approaches to prevent or cure impaired jaw sensorimotor functions and to thereby improve health and quality of life.

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