SPINOHYPOTHALAMIC AND SPINOTELENCEPHALIC TRACTS

几年前，我们在电生理学研究中注意到， 大鼠腰髓中的一些神经元可能 从下丘脑逆向激活，使用少量 电流 这些发现表明存在一种预测， 从脊髓传递躯体感觉和伤害感受信息 直接传送到下丘脑 我们使用了几种解剖学和 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，在大鼠中， 脊髓下丘脑束和脊髓丘脑束总数 神经元是相似的。 在脊髓的胸椎和骶骨水平， 脊髓下丘脑束神经元比 脊髓丘脑束神经元。 脊髓下丘脑束是 因为d可能是对这些领域的重要投入来源， 下丘脑被认为在自主神经， 对躯体感觉刺激的神经内分泌和情感反应。 在 我们将继续进行这项研究， 投影 在第一系列研究中，我们将确定 猴子中存在脊髓下丘脑束。 这一问题 应该直接检查，因为几个躯体感觉系统， 包括脊髓下丘脑束，在物种之间差异很大。 在第二组实验中，我们将使用一个强大的新替身 标记技术确定脊髓的数量和位置 在大鼠中，神经元投射到丘脑和下丘脑。 在第三组研究中，我们将使用电生理学 在大鼠中确定上行位置的技术 脊髓下丘脑束轴突，当它们通过延髓，脑桥， 和中脑这些研究还将表明， 脊髓下丘脑束轴突发出侧支投射到 脑干和中脑参与躯体感觉 处理. 如果是这样的话， SHT轴突的侧支投射将用双 标签研究。 在第四组也是最后一组研究中，我们将使用 解剖和生理技术来检查大量的 胸脊髓中的脊髓下丘脑束神经元。 在这些 研究，我们将确定下丘脑（和 端脑），其接收来自脑内神经元的直接投射， 胸髓 此外，我们还将从生理学角度研究 胸脊髓下丘脑束神经元对各种 定量的机械和热刺激。 我们还将确定 胸部SHT神经元是否被哺乳期幼崽激活。 的 拟议的研究将大大扩展我们对脊柱的认识， 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.