Adaptive brain activity changes during tongue movement with palatal coverage from fMRI data

Yuka Inamochi,Nobuo Usui,Noriyuki Wakabayashi,Masato Taira,Kenji Fueki

doi:10.1038/s41598-021-93332-3

Yuka Inamochi, Nobuo Usui + Show 3 more

Open Access

https://doi.org/10.1038/s41598-021-93332-3

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Abstract

Successful adaptation to wearing dentures with palatal coverage may be associated with cortical activity changes related to tongue motor control. The purpose was to investigate the brain activity changes during tongue movement in response to a new oral environment. Twenty-eight fully dentate subjects (mean age: 28.6-years-old) who had no experience with removable dentures wore experimental palatal plates for 7 days. We measured tongue motor dexterity, difficulty with tongue movement, and brain activity using functional magnetic resonance imaging during tongue movement at pre-insertion (Day 0), as well as immediately (Day 1), 3 days (Day 3), and 7 days (Day 7) post-insertion. Difficulty with tongue movement was significantly higher on Day 1 than on Days 0, 3, and 7. In the subtraction analysis of brain activity across each day, activations in the angular gyrus and right precuneus on Day 1 were significantly higher than on Day 7. Tongue motor impairment induced activation of the angular gyrus, which was associated with monitoring of the tongue’s spatial information, as well as the activation of the precuneus, which was associated with constructing the tongue motor imagery. As the tongue regained the smoothness in its motor functions, the activation of the angular gyrus and precuneus decreased.

Highlights

The tongue plays important roles in mastication1, swallowing[2], and articulation[3]
Difficulty with tongue movement was significantly higher on Day 1 compared to Days 0, 3, and 7, and non-significant differences were observed between Day 0, Day 3, and Day 7 (Fig. 1)
To the best of our knowledge, this is the first report on adaptive changes to palatal coverage in light of the relationship between tongue motor control and changes in brain activity

Summary

Introduction

The tongue plays important roles in mastication1, swallowing[2], and articulation[3]. Oral environment changes caused by the palate being covered impaired masticatory performance, but chewing ability fully recovered by day 7 post-insertion. Subjects may have been impaired tongue movement especially in bolus formation and transportation during mastication immediately post-insertion. After their chewing ability was recovered by 7 days, brain activity in which is known to be associated with chewing may have fully recovered. This recovery suggests that adapting to palatal coverage may be associated with cortical activity changes in certain specific regions required to learn tongue motor control. To observe the association between behavioral tongue movement and brain activity, subjects performed the new tongue motor task to simplify the tongue movement of bolus formation or transportation

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