TRIGEMINAL PRIMARY AFFERENT DEVELOPMENT

有相当多的证据表明，竞争性的相互作用发挥了主要作用。 在确定的形态学特性，和 功能性突触的分布，传入到一个给定的中央 神经系统核然而，目前还不清楚这是否是 例关于三叉神经（V）的主要神经支配的大鼠的 脑干事实上，有限的证据（贝尔福德和基拉基，'80;达勒姆 和伍尔西，'84）提出，这种相互作用可能发挥很少或 在这条通路的出生后发育中没有作用。我们将确定 竞争性相互作用是否影响产前和/或产后 通过进行三个实验来开发V初级传入。 首先，我们将使用顺行运输的二碘和辣根过氧化物酶 (HRP)标记胎儿和新生儿的单个V初级传入神经 大鼠这些纤维将在光学显微镜下重建， 由单个轴突形成的突触的分布将由 电镜其次，我们将从单个V主记录 胎儿和新生儿主V核的传入和神经元 大鼠以确定后者是否接受更大的会聚输入 而不是成年动物。这两项研究的结果将 使我们能够确定竞争性相互作用的底物 初级传入纤维存在于胎儿期或出生后早期。中 第三个也是最后一个实验，我们将使用胎儿外科技术来破坏 支配选定触须的初级传入神经的外周轴突 毛囊如果竞争性相互作用塑造了 触须相关的初级传入，这种病变应该把未受损的轴突 以“竞争优势”，并增加其中央规模 终端乔木我们将使用轴突内记录和HRP注射 技术，以确定是否发生这种情况。

There is considerable evidence that competitive interactions play a major role in determining the both the morphological properties of, and distributions of functional synapses made by, afferents to a given central nervous system nucleus. However, it is not at all clear whether this is the case with respect to the trigeminal (V) primary innervation of the rat's brainstem. In fact, limited evidence (Belford and Killackey, '80; Durham and Woolsey, '84) has suggested that such interactions may play little or no role in the postnatal development of this pathway. We will determine whether competitive interactions influence either the pre- and/or postnatal development of V primary afferents by carrying out three experiments. First, we will use anterograde transport of Di-I and horseradish peroxidase (HRP) to label individual V primary afferents in both fetal and neonatal rats. These fibers will be reconstructed in the light microscope and distributions of synapses made by single axons will be determined by electron microscopy. Secondly, we will record from individual V primary afferents and neurons in V nucleus principalis (PrV) in fetal and newborn rats to determine whether the latter cells receive greater convergent input than is the case in adult animals. The results of these two studies will allow us to determine whether the substrate for competitive interactions among V primary afferents exists in fetal or early postnatal life. In a third and final experiment, we will use fetal surgical techniques to damage the peripheral axons of primary afferents that innervate selected vibrissae follicles. If competitive interactions shape the central arbors of vibrissa-related primary afferents, such lesions should put undamaged axons at a "competitive advantage" and increase the size of their central terminal arbors. We will use intra-axonal recording and HRP injection techniques to determine whether or not this occurs.