SPINOHYPOTHALAMIC AND SPINOTELENCEPHALIC TRACTS

几年前，我们在电生理研究中注意到 大鼠腰椎脊髓内的大量神经元可能是 从下丘脑逆行激活使用少量的 电流。这些发现表明，存在一种投影，即 从脊髓携带体感和伤害性信息 直接进入下丘脑。我们用了几个解剖学和 生理技术来证实这种投射的存在。 有趣的是，我们的逆行追踪研究表明，在老鼠身上 下丘脑脊束和丘脑脊束总数 神经元是相似的。在脊髓的胸段和骶段，有 下丘脑棘束神经元的数量要比 脊髓丘脑束神经元。下丘脑脊束是 感兴趣，因为d可能是以下领域的重要投入来源 下丘脑被认为在自主神经中发挥重要作用， 神经内分泌和对躯体感觉刺激的情感反应。在……里面 在拟议的实验中，我们将继续对此进行研究 投影。在第一系列研究中，我们将确定 猴子的下丘脑棘束存在。这是一个很重要的问题 应该直接检查，因为有几个体感系统， 包括脊丘脑束，在不同物种之间有相当大的差异。 在第二组实验中，我们将使用一个强大的新替身 确定脊髓数目和位置的标记技术 投射到大鼠丘脑和下丘脑的神经元。 在第三组研究中，我们将使用电生理学 在大鼠中确定上升位置的技术 脊髓下丘脑束轴突通过延髓、桥脑、 和中脑。这些研究还将表明， 脊髓下丘脑束轴突向脑区投射侧支投射 参与躯体感觉的脑干和中脑 正在处理。如果是这样的话，显著的电生理证据 来自SHT轴突的侧支投射将用Double评估 标记研究。在第四组也是最后一组研究中，我们将使用 解剖学和生理学技术检查大量的 胸段脊髓内的脊髓下丘脑束神经元。在这些 研究中，我们将确定下丘脑的面积(和 端脑)，接受来自神经元的直接投射 胸髓。此外，我们还将对 胸段脊髓下丘脑束神经元对多种不同刺激的反应 定量的机械和热刺激。我们还将确定 哺乳仔鼠是否激活了胸腺SHT神经元。这个 拟议中的研究将极大地扩展我们对脊柱的了解 投射到下丘脑的脊髓神经元。

Several years ago, we noted during electrophysiological studies that a number of neurons in the lumbar spinal cords of rats could be antidromically activated from the hypothalamus using small amounts of current. These findings suggested the existence of a projection that carries somatosensory and nociceptive information from the spinal cord directly to the hypothalamus. We used several anatomical and physiological techniques to confirm the existence of this projection. Interestingly, our retrograde tracing studies indicated that in rats the total numbers of spinohypothalamic tract and spinothalamic tract neurons are similar. In thoracic and sacral levels of the cord, there are considerably more spinohypothalamic tract neurons than spinothalamic tract neurons. The spinohypothalamic tract is of interest because d may be an important source of input to areas of the hypothalamus that are thought to play important roles in autonomic, neuroendocrine and affective responses to somatosensory stimuli. In the proposed experiments we will continue our studies of this projection. In the first series of studies, we will determine whether a spinohypothalamic tract exists in monkeys. This is an issue that should be examined directly because several somatosensory systems, including the spinohypothalamic tract, vary considerably among species. In the second set of experiments, we will use a powerful new double labeling technique to determine the number and location of spinal cord neurons that project to both the thalamus and hypothalamus in rats. In the third set of studies, we will use electrophysiological techniques in rats to determine the location of ascending spinohypothalamic tract axons as they ascend through the medulla, pons, and midbrain . These studies will also indicate whether spinohypothalamic tract axons issue collateral projections to areas in the brainstem and midbrain that are involved in somatosensory processing. If so, electrophysiological evidence of prominent collateral projections from SHT axons will be evaluated with double labeling studies. In the fourth and final set of studies, we will use anatomical and physiological techniques to examine the large number of spinohypothalamic tract neurons in the thoracic spinal cord. In these studies, we will determine the areas of the hypothalamus (and telencephalon) that receive a direct projection from neurons in thoracic cord. In addition, we will physiologically examine the responses of thoracic spinohypothalamic tract neurons to a variety of quantitative mechanical and thermal stimuli. We will also determine whether thoracic SHT neurons are activated by suckling pups. The proposed studies should considerably expand our knowledge about spinal cord neurons that project to the hypothalamus.