Investigating cerebral asymmetries in non-human primates would facilitate to understand the evolutional traits of the human brain specialization related to language and other high-level cognition. However, brain asymmetrical studies of monkeys produced controversial results. Here, we investigated the cerebral asymmetries using a combination of the optimized voxel-based morphometry (VBM) and tract-based spatial statistics (TBSS) protocols in monkeys. The study-specific MRI and DTI-based templates were created in 66 adult Macaca fascicularis, and the asymmetrical index of grey and white matter was subsequently examined. The VBM analysis detected the well-known frontal and occipital petalias and confirmed the presence of leftward asymmetry in the ventral frontal cortex. A marked leftward asymmetry of anterior superior temporal gyrus but not posterior portion were found. We also identified grey matter asymmetries in some regions that were not previously reported including rightward anterior cingulate, insular cortex and thalamus, and leftward caudate. In contrast, the results of TBSS analysis for the first time revealed the robust leftwards asymmetries of corpus callosum (splenium and body), internal/external capsule, and white matter in middle temporal gyrus, adjacent thalamus and amygdala whereas the rightwards in uncinate fasciculus, posterior thalamic radiation and cerebral peduncle. These findings provide robust evidence of grey and white matter asymmetries in the brain of monkeys, which may extend the understanding of brain evolution in cerebral specialization.

中文翻译：

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基于体素的 MRI 和 DTI 分析揭示了成年猕猴的大脑不对称性

研究非人类灵长类动物的大脑不对称性将有助于了解与语言和其他高级认知相关的人类大脑专门化的进化特征。然而，对猴子的大脑不对称研究产生了有争议的结果。在这里，我们结合使用优化的基于体素的形态测量（VBM）和基于束的空间统计（TBSS）协议来研究猴子的大脑不对称性。在 66 只成年猕猴中创建了研究特定的 MRI 和基于 DTI 的模板，随后检查了灰质和白质的不对称指数。 VBM 分析检测到了众所周知的额叶和枕叶花瓣，并证实了腹侧额叶皮层存在向左不对称。发现颞上回前部明显向左不对称，但后部未发现。我们还发现了一些先前未报道过的区域的灰质不对称性，包括右侧前扣带回、岛叶皮质和丘脑以及左侧尾状核。相比之下，TBSS分析结果首次揭示了胼胝体（压部和胼胝体）、内/外囊以及颞中回、邻近丘脑和杏仁核白质的强烈向左不对称，而钩束向右，丘脑后辐射和大脑脚。这些发现提供了猴子大脑中灰质和白质不对称性的有力证据，这可能会扩展对大脑专业化中大脑进化的理解。