KINESTHETIC MECHANISMS IN THE TRIGEMINAL SYSTEM

三叉神经系统的动觉机制

基本信息

批准号：
2458581
负责人：
NORMAN CAPRA
金额：
$ 16.67万
依托单位：
UNIVERSITY OF MARYLAND BALTIMORE
依托单位国家：
美国
项目类别：
财政年份：
1990
资助国家：
美国
起止时间：
1990-08-01 至 1999-07-14
项目状态：
已结题

项目摘要

The objective of this project is to define neuronal mechanisms for mandibular kinesthesia. Orofacial position and movement information originates from receptors in jaw muscles, the temporomandibular joint (TMJ), and skin. This information is conveyed to trigeminal brainstem nuclei via neurons in the trigeminal ganglion and the mesencephalic nucleus. Our previous studies suggest the hypothesis that deep tissue inputs are somatotopically distributed in the trigeminal nuclei and in the thalamus so that perception old precise jaw movements results from spatially and temporally related activation of both deep (muscle and joint) and cutaneous receptors. Kinesthesia from postcranial structures requires thalamic relay of information to the somatosensory cortex. Although studies of cortical neurons support the existence of these pathways for jaw kinesthesia, little is known about the specific brainstem sources or the thalamic representation of this neural input. The first specific aim is to define the distribution, receptive field properties, and movement-related-responses of thalamic neurons by studying evoked potentials from nerve supplying the masseter muscle, the TMJ, and perioral region. Although kinesthetic information is signalled by larger diameter afferents, it is known that many smaller diameter afferents also respond to non-noxious mechanic;il stimuli including muscle stretch and joint movement in spinal systems. Similar properties for smaller diameter fibers supplying cranial tissues have not been documented. We hypothesize that some smaller diameter differents modulate central trigeminal neurons that process kinesthetic information. The second specific aim will examine the capacity of trigeminothalamic neurons to signal rate and positional changes during passive jaw movement. Algesic substances reliably activate small diameter muscle and joint afferents. The effects of intramuscular injections with an algesic substances on movement related-responses will be studied. The receptive fields of these neurons will be defined by graded mechanical and electrical stimulation, thalamic projections will be identified by antidromic stimulation. The third specific aim is to define the central distribution of physiologically-defined masseter muscle and TMJ afferents in Vi by intraaxonal staining. In the same experiment, thalamic projection neurons will be labeled by retrograde axonal transport methods. Ultrastructure of the synaptic input from identified afferents onto trigeminothalamic neurons will be studied. These experiments will lead to a fundamental understanding of oral sensory mechanisms important for adapting to acute changes in craniomandibular relationships and long term alterations related to aging or adaptation to dental prostheses.

该项目的目标是定义神经元机制下颌运动感觉。口面部位置和运动信息起源于颌肌、颞下颌关节的感受器（颞下颌关节）和皮肤。该信息被传达到三叉神经脑干细胞核通过三叉神经节和中脑神经元核。我们之前的研究提出了这样的假设：深层组织输入按体位分布在三叉神经核中丘脑，以便感知旧的精确下巴运动的结果深部（肌肉和肌肉）的空间和时间相关激活关节）和皮肤受体。颅后结构的动觉需要丘脑将信息传递到体感皮层。尽管皮层神经元的研究支持这些神经元的存在下颌运动的途径，具体的了解甚少脑干来源或该神经输入的丘脑表示。第一个具体目标是定义分布、感受野丘脑神经元的特性和运动相关反应研究供应咬肌的神经诱发电位颞下颌关节和口周区域。尽管动觉信息已发出信号通过较大直径的传入，我们知道许多较小直径的传入传入神经也对无害的机械刺激做出反应，包括脊柱系统中的肌肉伸展和关节运动。类似的属性对于供应颅骨组织的较小直径的纤维尚未记录在案。我们假设一些较小的直径差异会调节处理动觉信息的中枢三叉神经元。这第二个具体目标将检查三叉丘脑的能力被动下巴期间神经元发出信号速率和位置变化移动。止痛物质可靠地激活小直径肌肉，联合传入。肌肉注射止痛药的效果将研究与运动相关反应的物质。接受者这些神经元的领域将由分级机械和电刺激，丘脑投射将被识别逆向刺激。第三个具体目标是明确中央生理学定义的咬肌和颞下颌关节传入神经的分布在Vi中通过轴突内染色。在同一实验中，丘脑投射神经元将被逆行轴突运输标记方法。来自已识别传入的突触输入的超微结构将研究三叉丘脑神经元。这些实验将导致对口腔感觉机制的基本理解很重要适应颅颌关系的急剧变化和长期与衰老或适应假牙有关的术语变化。