RETICULOSPINAL & VESTIBULOSPINAL CONTROL OF BACK MUSCLES

下行系统包括延髓网状脊髓和外侧网状脊髓 前庭脊髓神经元已被证明是负责 促进哺乳动物行为的执行， 对细胞和分子分析来说是不寻常的： 雌激素依赖性生殖行为，脊柱前凸。收缩 深背部肌肉的程度没有看到其他行为， 对特定皮肤区域的体感刺激，是 脊柱前凸的神经肌肉基础。这里提出的研究逻辑上 扩展了我们实验室之前的电生理和行为工作。 I.已经建立了网状脊髓和侧前庭脊髓 控制深背部肌肉外侧最长肌，内侧 最长肌和横棘肌，我们将确定感觉 上行神经元和脑干下行神经元， 网状脊髓和前庭脊髓神经元群负责。使用 微刺激电流为30 μ alpha或更低，我们将确定 有效的网站，为深背部肌肉的激活，并使用低- 我们研制的逆行示踪剂的扩散应用方法 看看哪些神经元投射到这些部位。 二.因为下丘脑腹内侧核的损伤 减少脊柱前凸行为，我们将使用大腹内侧下丘脑 病变（电解或兴奋毒素微量注射）和电 刺激，以及控制病变和刺激，以发现一些 下丘脑内侧神经元影响神经元的方式， 网状脊髓和前庭脊髓神经元的能力， 转身，深背部肌肉运动神经元。在这个项目中，我们 将使用肌电图（EMG）记录的优势：这是一个 生产性的方法来测量输出的运动神经元池， 背部深层肌肉 三.由于几种下丘脑神经肽已经 根据其对脊柱前凸行为的影响， 有趣的是，研究他们影响深层激活的能力， 背肌运动神经元通过网状脊髓或前庭脊髓神经元。为 例如，已知促进生殖行为的十肽LHRH， 可以与β-内啡肽形成对比，后者可以减少脊柱前凸。 在整个过程中，对长期准备的大鼠进行研究， 之间的肌电图和行为观察，而较大的 在聚氨酯中可以有效地进行大量的参数研究， 麻醉动物在自由活动的动物中， 在各种行为情境中的激活会揭示出 活动模式，这是特定的极端背屈 脊柱前凸的姿势。 传统上，在神经生物学中， 前脑神经元通过大脑皮层传递信号的机制 脑干网状结构，影响执行的行为 通过位于脊髓中的运动神经元。这些实验扩展了 我们发现下丘脑神经元如何影响一个人的方法， 具体的依赖性生殖行为。

The descending systems comprised of medullary reticulospinal and lateral vestibulo-spinal neurons have been shown to be responsible for facilitating the execution of a mammalian behavior which has been proven to be unusually accessible to cellular and molecular analysis: the estrogen-progestin dependent reproductive behavior, lordosis. Contraction of the deep back muscles to an extent seen in no other behavior, upon somatosensory stimulation on specific regions of skin, is the neuromuscular basis of lordosis. The studies proposed here logically extend previous electrophysiological and behavioral work in our lab. I. Having already established reticulospinal and lateral vestibulospinal control over the deep back muscles lateral longissimus, medial longissimus and transverso-spinalis, we will determine the sensory ascending and brainstem descending neurons which project to the reticulospinal and vestibulospinal neuronal groups responsible. Using microstimulation with currents of 30mualpha or less, we will determine effective sites for the activation of deep back muscles, and use a low- diffusion method of application of retro-grade tracers developed in our lab to see which neurons are projecting to these sites. II. Since damage to the ventromedial nucleus of the hypothalamus can reduce lordosis behavior, we will use large ventromedial hypothalamic lesions (electrolytic or by excitotoxin microinjection) and electrical stimulation, as well as control lesions and stimulation, to discover some of the ways in which medial hypothalamic neurons can influence the ability of reticulospinal and vestibulospinal neurons to facilitate, in turn, deep back muscle motoneurons. Here, and throughout this project, we will use electromyographic (EMG) recording to advantage: it is a productive approach to measuring the output of the motoneuronal pools for deep back muscles. III. Since several hypothalamic neuropeptides have already been characterized with respect to their effects on lordosis behavior, it will be interesting to study their ability to influence the activation of deep back muscle motoneurons by reticulospinal or vestibulospinal neurons. For example, the decapeptide LHRH, known to facilitate reproductive behavior, can be contrasted to beta-endorphin, which decrease lordosis. Work with chronically prepared rats, throughout, will allow comparisons between electromyographic and behavioral observations, while larger numbers of parametric studies can be done efficiently in urethane- anesthetized animals. in the freely moving animals, comparisons of EMG activation across a variety of behavioral situations will reveal those patterns of activity which are specific to the extremely dorsiflexed posture of lordosis. Traditionally in neurobiology, it has been difficult to follow the mechanisms by which forebrain neurons could transmit signals through the brainstem reticular formation, to influence behaviors which are executed through motoneurons located in the spinal cord. These experiments extend our approach to discovering how hypothalamic neurons might influence one, concrete hormone-dependent reproductive behavior.