The neural basis of touch and proprioreception in the primate orofacial sensorimotor cortex

项目总结 在理解大脑皮层的表征以及触觉和本体的整合方面存在着根本的差距。 总体上伴随着身体运动，特别是伴随着运动动作的感觉。这代表着- 这是一个重要的问题，因为在了解它之前，口腔面部疼痛、感觉和运动的潜在机制- TOR损伤，以及感觉运动整合仍将在很大程度上令人费解。建议的目标是 研究旨在分离自然喂养行为中触觉和本体感觉的大脑皮层表征 通过使用创新的神经阻滞序列以及多电极阵列记录和3D跟踪 非人灵长类的舌头和下巴运动。舌头是研究这一现象的独特结构 因为它处于持续运动并且在接触其他口腔结构(例如，牙齿， 味觉、牙龈)。更重要的是，支配触觉和本体感觉的传入纤维 舌分别在三叉神经(舌神经支)和舌下神经进入中枢神经系统 分别是脑神经。这种独特的解剖结构使触觉和本体感觉的实验性分离- 提顿。中心假设是舌头的姿势和与其他口腔结构的接触反映在 初级躯体感觉和初级运动神经元的本体感觉和触觉相关反应 (MIO)口面部感觉运动皮质(OSMcx)区。这一假设将通过以下三个方面的研究来检验： CICIC目标：(1)确定关于舌位和与其他口腔结构接触的信息是如何编码的 在自然喂养期间，通过消除对舌头和周围口腔结构的触觉刺激，在MIO和SIO中 经三叉神经上、下颌感觉支的序贯神经阻滞，(2) 用皮质内微刺激分离神经元的运动反应和本体感觉反应 当舌头和其他口腔结构的触觉输入被阻断时，(ICMS)引起肌肉抽动，以及(3) 用光谱表征OSMcx触觉和本体感觉相关区域之间的功能连接 相干性分析及低强度ICMS对触觉区和本体感受区的影响 反过来说。这项拟议的研究使用了一种创新的方法，利用了 不同脑神经对口腔区域的影响，并集成了同时记录和跟踪 3D中的舌头和下巴运动。这项拟议的研究意义重大，因为它将在以下方面的结果之间架起桥梁 口腔躯体感觉的皮质表征及舌/颌骨生物力学研究进展 在机动行为中的运动，从而填补了该领域的一个重要空白。从这一过程中获得的知识 这项工作将为今后口腔体感、疼痛机制和感觉运动的研究奠定基础。 整合。归根结底，这些知识有可能为制定治疗策略提供信息 与牙种植体相关的感觉障碍，三叉神经痛，颞下颌关节紊乱病，口臭- 疼痛，以及恢复用于脑机接口的感觉反馈。

PROJECT SUMMARY There is a fundamental gap in understanding the cortical representations and integration of tactile and proprio- ceptive sensations accompanying bodily movements in general and oromotor behavior in particular. This repre- sents an important problem because until it is understood, the mechanisms underlying orofacial pain, sensorimo- tor impairments, and sensorimotor integration will remain largely incomprehensible. The goal of the proposed research is to dissociate the cortical representations of touch and proprioception during natural feeding behavior by using an innovative sequence of nerve blocks together with multi-electrode array recordings and 3D tracking of tongue and jaw movements in non-human primates. The tongue is a unique structure for investigating this because it is in constant motion and assumes various postures when touching other oral structures (e.g., teeth, palate, and gingiva) during feeding. More importantly, the tactile and proprioceptive afferent fibers innervating the tongue enter the central nervous system separately in trigeminal (lingual nerve branch) and hypoglossal cranial nerves, respectively. Such unique anatomy enables experimental dissociation of touch and propriocep- tion. The central hypothesis is that tongue posture and contact with other oral structures are reflected in the proprioception- and tactile-related responses of neurons in the primary somatosensory (SIo) and primary motor (MIo) areas of the orofacial sensorimotor cortex (OSMcx). This hypothesis will be tested by pursuing three spe- cific aims: (1) determine how information about tongue posture and contact with other oral structures is encoded in MIo and SIo during natural feeding by eliminating tactile stimuli to the tongue and surrounding oral structures through sequential nerve blocks to the maxillary and mandibular sensory branches of the trigeminal nerve, (2) dissociate the neurons’ motor response from a proprioceptive response by using intracortical microstimulation (ICMS) to evoke muscle twitches while tactile inputs to the tongue and other oral structures are blocked, and (3) characterize the functional connectivity between tactile- and proprioceptive-related regions in OSMcx by spectral coherence analysis and by the effects of low-intensity ICMS of a tactile region on a proprioceptive one and vice versa. The proposed research uses an innovative approach that leverages the unique sensory innervation of the oral region by different cranial nerves and integrates the simultaneous neural recording and tracking of the tongue and jaw movements in 3D. The proposed research is significant because it will bridge the results of decades of research on cortical representation of oral somatosensation and on the biomechanics of tongue/jaw movements during oromotor behavior, thus filling an important gap in the field. The knowledge gained from this work will lay the groundwork for future studies on oral somatosensation, pain mechanisms, and sensorimotor integration. Ultimately such knowledge has the potential to inform the development of strategies for treatment of sensory impairments associated with dental implants, trigeminal neuralgia, temporomandibular disorders, orofa- cial pain, and for the restoration of sensory feedback for use in brain-machine interface.