The relevance of heterotopic callosal fibers to interhemispheric connectivity of the mammalian brain.
The relevance of heterotopic callosal fibers to interhemispheric connectivity of the mammalian brain.
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DOI：
10.1093/cercor/bhac377
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发表时间：
2022-09
期刊：
影响因子：
3.7
通讯作者：
Diego Szczupak;Pamela Meneses Iack;Danielle Rayêe;Cirong Liu;R. Lent;F. Tovar-Moll;Afonso C. Silva
中科院分区：
文献类型：
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作者：
Diego Szczupak;Pamela Meneses Iack;Danielle Rayêe;Cirong Liu;R. Lent;F. Tovar-Moll;Afonso C. Silva
胼胝体（corpus callosum，CC）是大脑中最大的白色结构，也是大脑半球间通讯的主要通道。研究胼胝体的连接对于揭示大脑在健康和疾病中的解剖和功能组织至关重要。经典的解剖学研究的特点是大量的胼胝体轴突纤维连接主要是同伦皮质区。每当检测到，异位胼胝体纤维被归因于改变发芽和修剪机制的神经发育疾病，如CC发育不全（CCD）。我们假设这些异位连接由于其复杂的性质和方法的局限性而被严重低估。我们使用艾伦小鼠脑连接图谱和高分辨率弥散加权成像来识别和量化小鼠、绒猴和人类的同位和异位胼胝体连接。在所有3个物种中，我们发现，约75%的纵裂胼胝体连接是异位的，并包括中央核心的CC，而同伦纤维奠定沿着其周边。我们还表明，异位连接在确定大脑网络的全局属性中起着至关重要的作用。这些发现重塑了我们对胼胝体作为大脑半球间通信主要枢纽的角色的看法，直接影响了研究皮层连接，神经发育和神经发育障碍的多个神经科学领域。
The corpus callosum (CC) is the largest white matter structure and the primary pathway for interhemispheric brain communication. Investigating callosal connectivity is crucial to unraveling the brain's anatomical and functional organization in health and disease. Classical anatomical studies have characterized the bulk of callosal axonal fibers as connecting primarily homotopic cortical areas. Whenever detected, heterotopic callosal fibers were ascribed to altered sprouting and pruning mechanisms in neurodevelopmental diseases such as CC dysgenesis (CCD). We hypothesized that these heterotopic connections had been grossly underestimated due to their complex nature and methodological limitations. We used the Allen Mouse Brain Connectivity Atlas and high-resolution diffusion-weighted imaging to identify and quantify homotopic and heterotopic callosal connections in mice, marmosets, and humans. In all 3 species, we show that ~75% of interhemispheric callosal connections are heterotopic and comprise the central core of the CC, whereas the homotopic fibers lay along its periphery. We also demonstrate that heterotopic connections have an essential role in determining the global properties of brain networks. These findings reshape our view of the corpus callosum's role as the primary hub for interhemispheric brain communication, directly impacting multiple neuroscience fields investigating cortical connectivity, neurodevelopment, and neurodevelopmental disorders.