2021 Fiscal Year Final Research Report

Brain pathways conveying sensation from jaw-closing muscle spindles and the scientific basis of treatment with a dental splint for Tourette syndrome

Research Project

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Project/Area Number	18KK0259
Research Category	Fund for the Promotion of Joint International Research (Fostering Joint International Research (B))
Allocation Type	Multi-year Fund
Review Section	Medium-sized Section 57:Oral science and related fields
Research Institution	Osaka University
Principal Investigator	Atsushi Yoshida 大阪大学, 歯学研究科, 教授 (90201855)
Co-Investigator(Kenkyū-buntansha)	古田貴寛大阪大学, 歯学研究科, 講師 (60314184) 佐藤文彦大阪大学, 歯学研究科, 助教 (60632130) 村上旬平大阪大学, 歯学部附属病院, 講師 (70362689) 大原春香大阪大学, 歯学部附属病院, 医員 (40754726)
Project Period (FY)	2018-10-09 – 2022-03-31
Keywords	シナプス / 神経回路 / 筋感覚 / スプリント / 小脳
Outline of Final Research Achievements	In the present study, we have planned to verify that the proprioception arising from the jaw-closing muscle spindles (JCMSs) is conveyed from the oval paracentral nucleus (OPC) of the intralaminar thalamic nuclei to the cerebral cortex by electronmicroscopically observing the synapses made on the cell bodies of the OPC neurons. However, we could not finish this study because the worldwide spread of the corona virus infection unfortunately stopped our visiting Korea. However, we successfully demonstrated that the JCMS proprioception is conveyed via the supratrigeminal nucleus (Su5) and, then, the OPC to the primary and secondary somatosensory cortices and the granular insular cortex. In the supplemental study, we revealed that the JCMS proprioception via the Su5 is also transported bilaterally to the granular layer of the cerebellar cortex (especially to that of the simple lobule B, the crus II, and the flocculus).
Free Research Field	神経解剖学
Academic Significance and Societal Importance of the Research Achievements	学術的意義：筋や関節などに生ずる深部感覚は、意識に上らないので高次脳機能は担わないと誤認されてきたが、fMRIなどを用い、無意識感覚も上位脳に伝達され、情動、記憶、学習などの高次脳機能や脳疾患に関わることがわかった。本研究は、筋紡錘感覚の脳内伝導路と機能を初めて解明した。社会的意義：我々は、歯科スプリント装着後の咬合でトゥレット症候群（TS）の症状が軽快することを報告した（Murakami et al., 2019 Mov Disord.）。本研究で明らかになった閉口筋筋紡錘感覚の、視床髄板内核経由の大脳皮質投射と小脳投射がTSの治療効果を発現させていることの科学的根拠となった。