Manatee Cerebral Cortex and Comparative Volumetrics

海牛是海牛目的濒危物种，在大脑解剖学上表现出一些不同寻常的特征，这些特征似乎与它们独特的生活方式有关。海牛的总数量为1500-2000头，每年的死亡率约为150头。这一事实，再加上它们缓慢的生殖替代率，导致我们真正有可能看到的是研究这些独特哺乳动物生物学的最后机会。每一种哺乳动物都代表着一种自然的“实验”，每一个不寻常的物种都有助于确定可能的进化结果的范围，增加我们对进化潜力的理解，并使大脑的进化历史得以重建。目前，我们对海牛大脑的某些特殊特征与它们独特的生态位之间的关系有了一些了解；例如，脑/体重比小，大脑半球光滑，皮层细胞密度低。目前的研究将能够根据细胞染色模式识别海牛的不同皮质区域，并将通过与其他哺乳动物物种的比较提出这些区域的功能作用。计算机生成的大脑半球的三维重建和确定大脑主要分区的体积也是主要目标。

Manatees are endangered species of the Order Sirenia and exhibit several unusual traits in brain anatomy which appear to be related to their unique lifestyle. Manatees have an annual death rate of approximately 150 individuals from a total population of about 1500-2000. This fact, coupled with their slow reproductive replacement rate, leads to the real possibility exists that we are witnessing the last opportunity to study the biology of these unique mammals. Each mammalian species represents an "experiment" by nature and every unusual species helps define the range of possible evolutionary outcomes, increases our understanding of evolutionary potential, and enables the reconstruction of the evolutionary history of the brain. At present, we have some understanding of how certain peculiar features of manatee brains may be correlated with their unique ecological niche; for example, the small brain/body-weight ratio, smooth cerebral hemispheres, and low cell densities in the cortex. The present research will enable the identification of different cortical areas in the manatee based on cellular staining patterns and will suggest functional roles for these regions through comparisons with other mammalian species. Computer-generated three- dimensional reconstructions of cerebral hemispheres and determination of the volumes of the major brain divisions are also major objectives.