DENTAL PAIN: STUDIES ON TRIGEMINAL NUCLEUS CAUDALIS

该项目的目的是首次确定功能 最近发现的一种途径的特征，该途径被提出 是一条特定的疼痛路径。亚核尾侧亚核(SNC)是 参与处理疼痛信息的三叉神经感觉复合体 出现在口面部，并将其传递到丘脑。主 丘脑SNC的投射部位为腹后内侧核(VPM)。 板层内核团的位置越靠中间。据信， 疼痛的感觉辨别方面在VPM和 丘脑内侧区域的动机-情感成分。然而， 很少有研究研究内侧丘脑在疼痛中的作用。 尽管它与临床疼痛状态有潜在的相关性，但它的处理。 最近的解剖学研究描述了一种迄今未知的途径 发源于黑质边缘层，向中下核投射 (SM)位于丘脑内侧，终止于腹外侧眶(VLO) 大脑皮层。间接证据有力地表明，这条途径与 特别是在处理和传递疼痛信号方面。没有生理学上的 研究已经解决了这一潜在的非常重要的途径。这个 拟议的电生理学实验将研究功能 这条途径的性质。微电极将被放置在VLO皮质， 麻醉猫SM和SNc及其逆行兴奋SNc的实验研究 投射到Sm和Sm神经元的神经元，再投射到VLO皮质。 这些SNC和Sm投射神经元的功能特征将 通过应用各种伤害性和非伤害性来确定 对口腔面部的机械、热和电刺激 包括牙髓。黑质神经元的形态及其相互作用 SNC内的位置将通过细胞内注射确定 辣根过氧化物酶。刺激下行通路的作用 起源于大脑皮质、中脑导水管周围灰质和大脑中缝大脑角 我们将研究黑质神经元的反应。这些研究的结果 研究将有助于我们了解涉及到的机制 口腔面部的牙痛和其他疼痛状况，并可能 可能导致改进控制疼痛的临床方法。

This project aims to determine, for the first time, the functional characteristics of a recently discovered pathway which has been proposed to be a specific pain pathway. Subnucleus caudalis (SNC) is the major site in the trigeminal sensory complex involved in processing pain information arising in the orofacial region and in relaying it to thalamus. The main thalamic projection sites of SNC are the ventroposteromedial nucleus (VPM) and the more medially located intralaminar nuclei. It is believed that the sensory-discriminative aspects of pain are processed in VPM and the motivational-affective components in medial regions of thalamus. However, few studies have investigated the role of the medial thalamus in pain processing in spite of its potential relevance to clinical pain states. Recent anatomical studies have described a hitherto unknown pathway originating in the marginal layer of SNC, relaying in nucleus submedius (Sm) in medial thalamus and terminating in the ventrolateral orbital (VLO) cortex. Indirect evidence strongly suggests that this pathway is involved specifically in processing and relay of pain signals. No physiological studies have addressed this potentially very important pathway. The proposed electrophysiological experiments will study the functional properties of this pathway. Microelectrodes will be placed in VLO cortex, Sm and SNC of anesthetized cats and used to antidromically stimulate SNC neurons which project to Sm and Sm neurons which project to VLO cortex. The functional characteristics of these SNC and Sm projection neurons will be determined by applying various nociceptive and nonnociceptive mechanical, thermal and electrical stimuli to the orofacial region including the tooth pulp. The morphology of the SNC neurons and their location within SNC will be determined by intracellular injection of horseradish peroxidase. The effect of stimulating descending pathways originating in the cortex, periaqueductal gray and raphe magnus on the responses of SNC neurons will be investigated. The results of these studies will contribute to our understanding of the mechanisms involved in dental pain and other painful conditions of the orofacial region and may possibly lead to improved clinical methods for the control of pain.