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.

该项目的目的是定义神经元机制下颌运动率。口面位置和移动信息起源于下颌肌肉中的受体，颞下颌关节（TMJ）和皮肤。这些信息被传达给三叉神经脑干三叉神经节和中脑中神经元的核通过神经元的核核。我们先前的研究表明了深层组织的假设输入是在三叉神经核中分布的，在丘脑，以使人们感知旧精确的下颌运动来自在空间和时间上相关的深度激活（肌肉和关节）和皮肤受体。颅后结构的动力学需要将信息传递到体感皮层。尽管皮质神经元的研究支持了这些下颌动力学的途径，对特定的特定知之甚少脑干源或该神经输入的丘脑表示。第一个具体目的是定义分布，接受场特性和丘脑神经元的运动相关反应研究从供应咬合肌肉的神经中诱发的潜力， TMJ和牙区。尽管动力学信息是发出信号的通过较大的直径传入，已知许多较小的直径传入还对非毒性的机械师； IL刺激作出反应脊柱系统中的肌肉拉伸和关节运动。相似的属性对于供应颅组织的较小直径纤维尚未记录。我们假设一些较小的直径差异调节处理动力学信息的中央三叉神经元。这第二个特定目的将检查三角形丘脑的能力被动下颌期间信号速率和位置变化的神经元移动。高度物质可靠地激活小直径肌肉和关节传入。肌内注射的作用将研究运动相关子弹的物质。接受这些神经元的场将通过分级机械和电刺激，丘脑投影将通过抗体刺激。第三个具体目的是定义中央生理定义的咬肌和TMJ传入的分布在VI中通过律内染色。在同一实验中，丘脑投射神经元将通过逆行轴突转运标记方法。来自已识别传入的突触输入的超微结构将研究进入trigeminothalamic神经元。这些实验会导致对口服感觉机制的基本理解适应颅骨关系的急性变化和长期变化与牙齿假体衰老或适应相关的术语更改。