Ultrasound observations of tongue motor behavior.

In this investigation of motor skills of the tongue and age-related changes in motor behavior, upward and downward tongue movements with the teeth in centric occlusion and regulated by a metronome were recorded. The recordings were made by use of ultrasound diagnostic equipment with a 5 MHz electronic convex section scanning probe and a physiologic signal unit connected to a heart sound microphone in a group of young subjects and a group of older subjects. The results were as follows. (1) The system provided a useful method to evaluate motor skills of the tongue with sound signals showing clear images of the tongue surface and its movements. (2) The rhythm of tongue movements in older persons varied more than in younger persons. (3) The velocity in the upward and downward movements decreased and were statistically significant (p less than 0.01) in the older group. (4) The time lag between the sound signal and the start of touching the palate and floor of the mouth was longer (p less than 0.01) and the variations were greater in the older group. (5) The study showed age-related changes in motor behavior of the tongue.