Department of Oral Anatomy and Neurobiology, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan.
Department of Oral Anatomy and Neurobiology, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan; Department of Oral and Maxillofacial Surgery 2, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan.
Brain Res. 2020 Jul 15;1739:146830. doi: 10.1016/j.brainres.2020.146830. Epub 2020 Apr 9.
An invasive intralaminar thalamic stimulation and a non-invasive application of oral splint are both effective in treating tic symptoms of patients with Tourette syndrome (TS). Therefore, these two treatments may exert some influence on the same brain region in TS patients. We thus hypothesized that the proprioceptive input arising from the muscle spindles of jaw-closing muscles (JCMSs), known to be increased by the application of oral splint, is transmitted to the intralaminar thalamic nuclei. To test this issue, we morphologically and electrophysiologically examined the thalamic projections of proprioceptive input from the JCMSs to the intralaminar thalamic nuclei of rats. We first injected an anterograde tracer, biotinylated dextranamine, into the electrophysiologically identified supratrigeminal nucleus, which is known to receive proprioceptive inputs from the JCMSs via the trigeminal mesencephalic neurons. A moderate number of biotinylated dextranamine-labeled axon terminals were bilaterally distributed in the oval paracentral nucleus (OPC) of the intralaminar thalamic nuclei. We also detected electrophysiological responses to the electrical stimulation of bilateral masseter nerves and to sustained jaw-opening in the OPC. After injection of retrograde tracer (cholera toxin B subunit or Fluorogold) into the OPC, neuronal cell bodies were retrogradely labeled in the rostrodorsal portion of the bilateral supratrigeminal nucleus. Here, we show that proprioceptive inputs from the JCMSs are conveyed to the OPC in the intralaminar nuclei via the supratrigeminal nucleus. This study can help to understand previously unrecognized pathways of proprioception ascending inputs from the brainstem to the thalamus, which may contribute to treatments of TS patients.
侵入性内板层丘脑刺激和非侵入性口腔夹板应用均可有效治疗抽动秽语综合征（TS）患者的抽动症状。因此，这两种治疗方法可能对 TS 患者的同一脑区产生一些影响。我们因此假设，咀嚼肌（JCMS）的肌梭产生的本体感受输入，已知通过应用口腔夹板会增加，会传递到内板层丘脑核。为了检验这个问题，我们形态学和电生理学检查了来自 JCMS 的本体感受输入到大鼠内板层丘脑核的丘脑投射。我们首先将顺行示踪剂生物素化葡聚糖胺注入电生理鉴定的三叉神经中脑核，已知该核通过三叉神经中脑神经元接收来自 JCMS 的本体感受输入。在中线核的卵圆形旁中央核（OPC）中双侧分布着大量生物素化葡聚糖胺标记的轴突末梢。我们还在 OPC 中检测到双侧咬肌神经电刺激和持续张口引起的电生理反应。在 OPC 中注射逆行示踪剂（霍乱毒素 B 亚单位或 Fluorogold）后，双侧三叉神经中脑核的头侧背侧部分标记有神经元胞体。在这里，我们表明 JCMS 的本体感受输入通过三叉神经中脑核传递到中线核的 OPC。这项研究有助于理解从前未被认识的从脑干到丘脑的本体感受传入的上行途径，这可能有助于治疗 TS 患者。
