Department of Anthropology, Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington, DC, 20052, USA.
Comparative Pathology Lab-RARC, University of Wisconsin, Madison, WI, 53726, USA.
Brain Struct Funct. 2019 Jan;224(1):239-251. doi: 10.1007/s00429-018-1751-9. Epub 2018 Oct 10.
Despite being closely related, bonobos and chimpanzees exhibit several behavioral differences. For instance, studies indicate that chimpanzees are more aggressive, territorial, and risk-taking, while bonobos exhibit greater social tolerance and higher rates of socio-sexual interactions. To elucidate the potential neuroanatomical variation that accompanies these differences, we examined the microstructure of selected brain areas by quantifying the neuropil fraction, a measure of the relative tissue area occupied by structural elements of connectivity (e.g., dendrites, axons, and synapses) versus cell bodies. In bonobos and chimpanzees, we compared neuropil fractions in the nucleus accumbens (NAc; core and shell), amygdala (whole, accessory basal, basal, central and lateral nuclei), anterior cingulate cortex (ACC; dorsal and subgenual), anterior insular cortex (AIC), and primary motor cortex (M1). In the dorsal ACC and frontoinsular cortex (FI) we also quantified numbers of von Economo neurons (VENs), a unique subset of neurons thought to be involved in rapid information processing during social interactions. We predicted that the neuropil fraction and number of VENs in brain regions associated with socio-emotional processing would be higher in bonobos. In support of this hypothesis, we found that bonobos had significantly greater neuropil in the central and accessory basal nuclei of the amygdala, as well as layers V-VI of the subgenual ACC. However, we did not find a difference in the numbers of VENs between the two species. These findings support the conclusion that bonobo and chimpanzee brains differ in the anatomical organization of socio-emotional systems that may reflect species-specific variation in behavior.
尽管密切相关，但倭黑猩猩和黑猩猩表现出几种行为差异。例如，研究表明，黑猩猩更具攻击性、更具领地性和冒险性，而倭黑猩猩表现出更大的社会容忍度和更高的社交性互动率。为了阐明伴随这些差异的潜在神经解剖学变化，我们通过量化神经胶质分数来检查选定大脑区域的微观结构，神经胶质分数是衡量连接结构元素（例如树突、轴突和突触）相对于细胞体占据的相对组织面积的指标。在倭黑猩猩和黑猩猩中，我们比较了伏隔核（NAc；核心和壳）、杏仁核（整体、附属基底、基底、中央和外侧核）、前扣带皮层（ACC；背侧和亚皮质）、前岛叶皮层（AIC）和初级运动皮层（M1）的神经胶质分数。在背侧 ACC 和额岛叶皮层（FI）中，我们还量化了冯·埃科诺莫神经元（VENs）的数量，VENs 是一种独特的神经元子集，被认为参与社交互动期间的快速信息处理。我们预测，与社会情感处理相关的大脑区域的神经胶质分数和 VENs 数量在倭黑猩猩中会更高。为了支持这一假设，我们发现倭黑猩猩的杏仁核中央和附属基底核以及亚皮质 ACC 的 V-VI 层的神经胶质分数明显更高。然而，我们没有发现两个物种之间 VENs 数量的差异。这些发现支持了这样的结论，即倭黑猩猩和黑猩猩的大脑在社会情感系统的解剖组织上存在差异，这可能反映了行为上的物种特异性变化。
