TRIGEMINAL PRIMARY AFFERENT DEVELOPMENT

有相当多的证据表明，竞争性互动在 在确定和的形态属性中的作用 传入中枢的功能性突触的分布 神经系统核团。然而，目前完全不清楚这是否是 大鼠三叉神经(V)初级神经支配1例 脑干。事实上，证据有限(Belford and Killackey，‘80；Durham 和Woolsey，‘84)提出，这种互动可能起不到什么作用或 在这一途径的出生后发育过程中不起作用。我们将决定 竞争性相互作用是否会影响出生前和/或出生后 通过三个实验研究V类初级传入神经的发育。 首先，我们将使用Di-I和辣根过氧化物酶的顺行运输 (HRP)标记胎儿和新生儿的V类初级传入神经元 老鼠。这些纤维将在光学显微镜中重建，并 由单个轴突形成的突触的分布将由以下因素决定 电子显微镜。其次，我们将从个人V小学开始录制 胎儿和新生儿V主核的传入和神经元 以确定后一种细胞是否接受更大的汇聚输入 在成年动物身上也是如此。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 V类初级传入神经存在于胎儿或出生后早期。在一个 第三次也是最后一次实验，我们将使用胎儿外科技术来损伤 支配所选触须的初级传入的外周轴突 毛囊。如果竞争的相互作用塑造了 与触觉相关的初级传入，这种损害应该使未受损的轴突 具有竞争优势，并扩大其中心规模 终端乔木。我们将使用轴突内记录和HRP注射 确定是否发生这种情况的技术。

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.