Department of Anthropology, University of California, San Diego, La Jolla, California 92093, USA.
J Comp Neurol. 2012 Sep 1;520(13):3035-54. doi: 10.1002/cne.23118.
In human and nonhuman primates, the amygdala is known to play critical roles in emotional and social behavior. Anatomically, individual amygdaloid nuclei are connected with many neural systems that are either differentially expanded or conserved over the course of primate evolution. To address amygdala evolution in humans and our closest living relatives, the apes, we used design-based stereological methods to obtain neuron counts for the amygdala and each of four major amygdaloid nuclei (the lateral, basal, accessory basal, and central nuclei) in humans, all great ape species, lesser apes, and one monkey species. Our goal was to determine whether there were significant differences in the number or percent of neurons distributed to individual nuclei among species. Additionally, regression analyses were performed on independent contrast data to determine whether any individual species deviated from allometric trends. There were two major findings. In humans, the lateral nucleus contained the highest number of neurons in the amygdala, whereas in apes the basal nucleus contained the highest number of neurons. Additionally, the human lateral nucleus contained 59% more neurons than predicted by allometric regressions on nonhuman primate data. Based on the largest sample ever analyzed in a comparative study of the hominoid amygdala, our findings suggest that an emphasis on the lateral nucleus is the main characteristic of amygdala specialization over the course of human evolution.
在人类和非人类灵长类动物中，杏仁核被认为在情绪和社会行为中起着至关重要的作用。从解剖学上看，单个杏仁核核与许多神经系统相连，这些神经系统在灵长类动物进化过程中要么有所扩展，要么保持不变。为了研究人类和我们最亲近的灵长类亲属——猿类的杏仁核进化，我们使用基于设计的立体学方法，对人类、所有大猿种、小猿种和一种猴种的杏仁核和四个主要杏仁核核（外侧核、基底核、附属基底核和中央核）进行了神经元计数。我们的目标是确定在物种间，分配给各个核的神经元数量或百分比是否存在显著差异。此外，还对独立对比数据进行了回归分析，以确定是否有任何单个物种偏离了生长曲线趋势。有两个主要发现。在人类中，外侧核包含杏仁核中数量最多的神经元，而在猿类中，基底核包含数量最多的神经元。此外，人类的外侧核比基于非人类灵长类动物数据的生长曲线回归预测的神经元多 59%。基于对人科杏仁核进行的比较研究中分析过的最大样本，我们的研究结果表明，在人类进化过程中，对外侧核的重视是杏仁核特化的主要特征。
