RETICULOSPINAL & VESTIBULOSPINAL CONTROL OF BACK MUSCLES

由延髓、网状、脊髓和外侧组成的下行系统 前庭-脊髓神经元已被证明对 促进已被证明的哺乳动物行为的执行 非同寻常地可以进行细胞和分子分析： 雌激素-孕激素依赖的生殖行为，前凸。收缩 背部肌肉的深度，达到了其他任何行为都看不到的程度 对皮肤特定区域的体感刺激，是 前凸的神经肌肉基础。这里提出的研究是合乎逻辑的 扩展我们实验室以前的电生理和行为研究。 已经建立了网状脊髓和外侧前庭脊髓 对背部内侧外侧纵肌的控制 最长肌和横棘肌，我们将确定感官 上行和脑干下行神经元投射到 网状脊髓和前庭脊髓神经元群负责。vbl.使用 用30-α或更小的电流进行微刺激，我们将确定 有效激活背部肌肉的有效部位，并使用低位- 我校研制的复古示踪剂扩散法 实验室来看看哪些神经元投射到这些部位。 由于下丘脑腹内侧核的损伤可以 减少前凸行为，我们将使用较大的下丘脑腹内侧 病变(电解性或通过微量注射激毒素)和电击 刺激，以及控制损伤和刺激，以发现一些 下丘脑内侧神经元如何影响 网状脊髓和前庭脊髓神经元促进 转身，背部肌肉运动神经元。在这里，以及在整个项目中，我们 将使用肌电(EMG)记录的优势：这是一种 测量运动神经元池输出的有效方法 背部深处的肌肉。 由于几种下丘脑神经肽已经被 以它们对前凸行为的影响为特征，它将 很有兴趣研究它们影响深部激活的能力 背部肌肉运动神经元由网状脊髓或前庭脊髓神经元组成。为 例如，十肽LHRH，已知可以促进生殖行为， 可以与减少前凸的β-内啡肽形成对比。 从头到尾，用长期准备好的大鼠进行研究将允许进行比较 肌电和行为观察之间的差异，虽然 大量的参数研究可以在氨基甲酸酯中高效地完成- 麻醉的动物。在自由活动的动物中，肌电的比较 在各种行为情况下的激活将揭示 极度背屈的人特有的活动模式 前凸的姿势。 传统上，在神经生物学中，很难遵循 前脑神经元通过脑内神经元传递信号的机制 脑干网状结构，影响被执行的行为 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， 具体的激素依赖的生殖行为。

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.