Schenker Natalie M, Desgouttes Anne-Marie, Semendeferi Katerina
Anthropology Department, University of California at San Diego, USA.
J Hum Evol. 2005 Nov;49(5):547-69. doi: 10.1016/j.jhevol.2005.06.004. Epub 2005 Aug 1.
Cognitive functions and information processing recruit discrete neural systems in the cortex and white matter. We tested the idea that specific regions in the cerebrum are differentially enlarged in humans and that some of the neural reorganizational events that took place during hominoid evolution were species-specific and independent of changes in absolute brain size. We used magnetic resonance images of the living brains of 10 human and 17 ape subjects to obtain volumetric estimates of regions of interest. We parcellated the white matter in the frontal and temporal lobes into two sectors, including the white matter immediately underlying the cortex (gyral white matter) and the rest of white matter (core). We outlined the dorsal, mesial, and orbital subdivisions of the frontal lobe and analyzed the relationship between cortex and gyral white matter within each subdivision. For all regions analyzed, the observed human values are as large as expected, with the exception of the gyral white matter, which is larger than expected in humans. We found that orangutans had a relatively smaller orbital sector than any other great ape species, with no overlap in individual values. We found that the relative size of the dorsal subdivision is larger in chimpanzees than in bonobos, and that the ratio of gyral white matter to cortex stands out in Pan in comparison to Gorilla and Pongo. Individual variability, possible sex differences, and hemispheric asymmetries were present not only in humans, but in apes as well. Differences in the distribution of neural connectivity and cortical sectors were identified among great ape species that share similar absolute brain sizes. Given that these regions are part of neural systems with distinct functional attributes, we suggest that the observed differences may reflect different evolutionary pressures on regulatory mechanisms of complex cognitive functions, including social cognition.
认知功能和信息处理会调用大脑皮层和白质中不同的神经系统。我们验证了这样一种观点，即大脑中特定区域在人类中会有不同程度的扩大，并且在类人猿进化过程中发生的一些神经重组事件是物种特异性的，且与绝对脑容量的变化无关。我们使用了10名人类和17只猿类受试者活体大脑的磁共振图像来获取感兴趣区域的体积估计值。我们将额叶和颞叶的白质划分为两个部分，包括紧挨着皮层的白质（脑回白质）和其余的白质（核心）。我们勾勒出额叶的背侧、内侧和眶部亚区，并分析了每个亚区内皮层与脑回白质之间的关系。对于所有分析的区域，观察到的人类数值与预期的一样大，但脑回白质除外，其在人类中比预期的要大。我们发现，红毛猩猩的眶部亚区相对比其他任何大猩猩物种都要小，个体数值没有重叠。我们发现，黑猩猩背侧亚区的相对大小比倭黑猩猩的大，并且与大猩猩和红毛猩猩相比，泛猿属（Pan）的脑回白质与皮层的比例很突出。个体变异性、可能的性别差异和半球不对称性不仅在人类中存在，在猿类中也存在。在具有相似绝对脑容量的大猩猩物种之间，发现了神经连接分布和皮层亚区的差异。鉴于这些区域是具有不同功能属性的神经系统的一部分，我们认为观察到的差异可能反映了对包括社会认知在内的复杂认知功能调节机制的不同进化压力。
