An exploratory investigation of the effects of whole-head vibration on jaw movements.

The perturbing effects of vibration applied to head and body structures are known to destabilize motor control and elicit corrective responses. Although such vibration response testing may be informative for identifying sensorimotor deficits, the effect of whole-head vibration has not been tested on oromotor control. The purpose of this study was to determine how jaw movements respond to the perturbing effects of whole-head vibration during jaw motor tasks. Ten healthy adults completed speech, chewing, and two syllable repetition tasks with and without whole-head vibration. Jaw movements were recorded using 3D optical motion capture. The results showed that the direction and magnitude of the response were dependent on the task. The two syllable repetition tasks responded to vibration, although the direction of the effect differed for the two tasks. Specifically, during vibration, jaw movements became slower and smaller during the syllable repetition task that imposed speed and spatial precision demands, whereas jaw movements became faster and larger during the syllable repetition task that only imposed speed demands. In contrast, jaw movements were unaffected by the vibration during speech and chewing. These findings suggest that the response to vibration may be dependent on spatiotemporal demands, the availability of residual afferent information, and robust feedforward models.