Unidad Ejecutora de Estudios en Neurociencias y Sistemas Complejos (CONICET-UNAJ-HEC), Florencio Varela, Buenos Aires, Argentina.
Instituto de Biología Evolutiva (UPF-CSIC), Barcelona, Spain.
Brain Struct Funct. 2022 Mar;227(2):469-477. doi: 10.1007/s00429-021-02371-z. Epub 2021 Aug 29.
Brain lateralization is a widespread phenomenon although its expression across primates is still controversial due to the reduced number of species analyzed and the disparity of methods used. To gain insight into the diversification of neuroanatomical asymmetries in non-human primates we analyze the endocasts, as a proxy of external brain morphology, of a large sample of New World monkeys and test the effect of brain size, home range and group sizes in the pattern and magnitude of shape asymmetry. Digital endocasts from 26 species were obtained from MicroCT scans and a set of 3D coordinates was digitized on endocast surfaces. Results indicate that Ateles, Brachyteles, Callicebus and Cacajao tend to have a rightward frontal and a leftward occipital lobe asymmetry, whereas Aotus, Callitrichinae and Cebinae have either the opposite pattern or no directional asymmetry. Such differences in the pattern of asymmetry were associated with group and home range sizes. Conversely, its magnitude was significantly associated with brain size, with larger-brained species showing higher inter-hemispheric differences. These findings support the hypothesis that reduction in inter-hemispheric connectivity in larger brains favors the lateralization and increases the structural asymmetries, whereas the patterns of shape asymmetry might be driven by socio-ecological differences among species.
大脑偏侧化是一种普遍现象，但由于分析的物种数量较少，以及使用方法的差异，灵长类动物的大脑偏侧化表现仍存在争议。为了深入了解非人类灵长类动物神经解剖学不对称的多样化，我们分析了大量新世界猴的内颅骨，作为外部大脑形态的代表，并测试了大脑大小、活动范围和群体大小对形状不对称模式和幅度的影响。从 MicroCT 扫描中获得了 26 个物种的数字内颅骨，并在内颅骨表面上数字化了一组 3D 坐标。结果表明，绒毛猴、短尾猴、绒毛蛛猴和丛尾猴倾向于表现出右前叶和左枕叶的不对称性，而夜猴、卷尾猴和松鼠猴则表现出相反的模式或没有方向性的不对称性。这种不对称模式的差异与群体和活动范围大小有关。相反，其幅度与大脑大小显著相关，大脑较大的物种表现出更高的半球间差异。这些发现支持了这样一种假设，即大脑中半球间连接的减少有利于大脑偏侧化并增加结构不对称性，而形状不对称的模式可能是由物种间的社会生态差异驱动的。
