Dissertation Research: Structural Differences in the Corpus Callosum of Macaca fascicularis and Pan Troglodytes by Confocal Microscopy

这是一项关于大脑中作为两个大脑半球之间主要交流通道的部分--胼胝体--的性别差异的研究。 本研究将使用激光扫描共聚焦显微镜检查两种高等灵长类动物的大脑，食蟹猴（Macaca fascicularis）和普通黑猩猩（Pan troglodytes），这是显微成像的最新进展，可以进行以前无法进行的调查和分析。 该项目的数据将提供有关非人类灵长类动物胼胝体的基础生物学的新信息，并提供一个能够重建灵长类动物大脑性别差异进化的基础。 例如，这项研究的结果可能直接关系到对旧大陆猴子和类人猿中存在的男女认知和/或语言差异的观察。 拟议的研究将通过检验以下假设来解决这些主张：食蟹猴和黑猩猩胼胝体中的性别差异存在于与总胼胝体区域和区域胼胝体区域相关的总体形态中，以及有髓和无髓神经纤维的数量方面。 有关纤维组成的知识可以揭示两个大脑半球相互交流的能力，以及这种交流可能发生的速度。 例如，穿过胼胝体的纤维的数量将反映两半球之间的连接程度，并提供对侧化（即，左-右划分）的功能。 有髓纤维的大小（即，那些被有助于传导速度的髓鞘包围的神经纤维）穿过胼胝体将提供对信息在两个半球之间传递的速度的洞察。一般来说，神经纤维的直径越大，信号传导的速度就越快。 在非人类灵长类动物大脑的一个基本上未被探索的区域上解决这些基本问题的能力将为人类大脑中的性别差异如何产生提供重要的新信息。

This is an investigation of sexual differences in that part of the brain which serves as the major communicating highway between the two cerebral hemispheres, the corpus callosum. This study will examine the brains of two species of higher primates, the cynomolgus monkey (Macaca fascicularis) and the common chimpanzee (Pan troglodytes) using laser scanning confocal microscopy, a recent advancement in microscopic imaging that allows for a level of investigation and analysis not available previously. Data from this project will offer new information on both the basic biology of the nonhuman primate corpus callosum and provide a substrate which will enable reconstruction of the evolution of sex differences in the primate brain. For example, findings from this study may directly relate to observations on the existence of male-female cognitive and/or linguistic differences in Old World monkeys and great apes. The proposed research will address these claims by testing the hypothesis that sex differences in the corpus callosum of Macaca fascicularis and Pan troglodytes are present in gross morphology related to total and regional callosal areas, and also with regard to the number of myelinated and unmyelinated nerve fibers. Knowledge about fiber composition can shed light on the ability of the two cerebral hemispheres to communicate with each other, and the speed at which this communication may occur. For example, the quantity of fibers traversing the corpus callosum will reflect the degree of connectivity between the hemispheres, and offer insight into the lateralization (i.e., left-right compartmentalization) of functions. The size of the myelinated fibers (i.e., those nerve fibers surrounded by a myelin sheath which aids in conduction velocity) which pass through the corpus callosum will offer insight into the speed at which messages are passed between the hemispheres. In general, the larger the diameter of the nerve fiber the faster the signal will be conducted. The ability to address these fundamental questions on a largely unexplored region of the nonhuman primate brain will offer significant new information on how sexual differences in the human brain came to be.