RUI: Development and Maturation of Olfactory Centers in theLobster: Influences of Serotonin and Adult Neurogenesis

9709514 BELTZ博士将研究龙虾大脑中神经元发育和可塑性的两个相关问题。这项研究的一个领域建立在最近对各种生物体的研究基础上，这些研究指出了增殖细胞在成人大脑中产生新神经元的潜在贡献。在龙虾成熟的嗅觉通路中，新神经元的诞生已经在受体群体和参与嗅觉加工和信息传递到更高中心的中间神经元中得到证实。将新细胞整合到现有回路中，可能提供了一种改变成熟大脑嗅觉学习或整合的方法。拟议的研究将检查类固醇激素和其他因素（如嗅觉周围触角的损伤）对神经发生的可能调节。神经元死亡（“细胞凋亡”）对成熟嗅觉系统完善的可能贡献也将被解决。第二组研究将检验神经递质血清素在大脑发育中的作用。与嗅觉通路细胞成分的明显逐渐变化相反，龙虾嗅觉系统的5 -羟色胺能输入似乎非常稳定。已确定的支配嗅叶的血清素能中间神经元在胚胎发育早期出现，并持续整个幼虫和成虫生命。胚胎期血清素耗竭导致嗅觉靶区的生长急剧减缓。这意味着血清素通常会促进这些区域的生长。在未来的研究中，将通过比较暴露于降低、正常和增加血清素水平的特定嗅觉中间神经元组的发育来研究这种生长迟缓的细胞基础。这些研究与高等生物的发育机制有关，因为即使在系统发育上遥远的物种中，嗅觉通路的组织和加工之间也有许多相似之处。此外，这些研究将探索神经回路发育和维持的基本机制，这可能适用于其他生物的光谱。

9709514 BELTZ Dr. Beltz will investigate two related issues of neuronal development and plasticity in the lobster brain. One area of this research builds on recent studies in a variety of organisms that point to the potential contibution of proliferating cells that generate new neurons in the adult brain. The birth of new neurons in the mature olfactory pathway of the lobster has been demonstrated both in the receptor population and in interneurons that are involved in olfactory processing and transmission of information to higher centers. Integration of new cells into existing circuits may provide a means of modifying olfactory learning or integration in the mature brain. The proposed studies will examine the possible regulation of neurogenesis by steroid hormones and other factors, such as damage to the antennules in the olfactory periphery. The possible contribution of neuronal death ("apoptosis") to the refinement of the mature olfactory system also will be addressed. The second set of studies will examine the role of the neurotransmitter serotonin in brain development. In contrast to the apparent gradual changes in cellular components of the olfactory pathway, the serotonergic input to the olfactory system appears to be very stable in lobsters. Identified serotonergic interneurons innervating the olfactory lobes appear early in embryogenesis and persist throughout larval and adult life. Serotonin depletion during the embryonic period results in a dramatic slowing of growth in olfactory target regions. This implies that serotonin normally promotes the growth of these regions. In future studies the cellular bases of this growth retardation will be investigated by comparing the development of specific groups of olfactory interneurons exposed to reduced, normal and increased levels of serotonin. These studies are relevant to developmental mechanisms in higher organisms because there are many parallels between the organization of olfactory pathways and processing even in phylogen etically distant species. In addition, these studies will explore basic mechanisms involved in the development and maintenance of neural circuits which may be applicable in a spectrum of other organisms.