Characteristics of complex voluntary mandibular movements in the monkey before and after destruction of most jaw muscle spindle afferents

Abstract

<h2>Summary</h2> To study the role of proprioception in voluntary movement, two monkeys were trained to use their mandible to control the position of a lever that electronically loaded the jaw. They "tracked" stationary and moving targets both with and without visual feedback. Lesions of the tract of the mesencephalic nucleus of the fifth nerve, which destroyed most jaw muscle proprioceptors, did not interfere, even transiently, with the ability to perform the basic requirements of the jaw tracking tasks. There was an increase in low-frequency jaw tremor, and a small increase in the tracking error when the visual feedback signal was present, but these effects may have resulted from damage to other neural pathways. We conclude that muscle spindles are not necessary to perform well-practiced movements.