Department of Anthropology, University College London, London, WC1H 0BW, UK.
Brain Struct Funct. 2012 Apr;217(2):531-47. doi: 10.1007/s00429-011-0338-5. Epub 2011 Aug 24.
The long-held view that brain size can be used as an index of general functional capacity across mammals is in conflict with increasing evidence for phyletic differences in cellular organization. Furthermore, it is poorly understood how the internal cellular organization of the brain covaries with overall brain size variation. Using design-based stereology, we quantified glial cell and neuronal densities in the primary visual cortex of 71 mammalian species (spanning 11 orders) to test how those cellular densities are influenced by phylogeny, behavior, environment, and anatomy. We further tested cellular densities against mode of placentation to determine whether a relationship may exist. We provide evidence for cellular signatures of phylogenetic divergence from the mammalian trend in primates and carnivores, as well as considerably divergent scaling patterns between the primate suborders, Strepsirrhini and Haplorrhini, that likely originated at the anthropoid stem. Finally, we show that cellular densities in the mammalian cortex relate to the variability of maternal resources to the fetus in a species.
长期以来，人们一直认为大脑大小可以作为哺乳动物整体功能能力的指标，但越来越多的证据表明细胞组织在系统发生上存在差异。此外，人们对于大脑内部细胞组织如何与大脑总体大小变化相关还知之甚少。本研究采用基于设计的体视学方法，对 71 种哺乳动物（涵盖 11 个目）的初级视觉皮层中的神经胶质细胞和神经元密度进行了定量分析，以检验这些细胞密度如何受到系统发生、行为、环境和解剖结构的影响。我们还进一步将细胞密度与胎盘形成方式进行了对比，以确定两者之间是否存在关系。研究结果表明，在灵长类动物和食肉动物中，存在与哺乳动物趋势不同的细胞特征，以及在灵长类动物的两个亚目中（原猴亚目和简鼻亚目）存在明显不同的缩放模式，这种模式可能起源于类人猿的主干。最后，我们发现哺乳动物皮层中的细胞密度与物种中母体资源对胎儿的变异性有关。
