Karlsson Emma M, Verhelst Helena, Vingerhoets Guy
Department of Experimental Clinical and Health Psychology, Ghent University, Ghent, Belgium.
Ghent Institute for Metabolic and Functional Imaging (GIfMI), Ghent University, Ghent, Belgium.
Brain Struct Funct. 2025 May 21;230(5):69. doi: 10.1007/s00429-025-02931-7.
Situs inversus totalis (SIT), a rare condition involving the complete reversal of thoracic and abdominal organ placement, provides a unique model for investigating potential relationships between visceral and cerebral asymmetries. In this study, we examined whether white matter asymmetries are altered in a group of 21 SIT participants compared with 21 matched situs solitus (SO) controls. This sample represents the largest cohort of SIT individuals studied to date. Using fixel-based analysis, an advanced diffusion magnetic resonance imaging framework, we compared micro- and macrostructural white matter asymmetries across the whole brain between the two groups, specifically assessing fiber density and cross-section (FDC). Both groups showed extensive yet comparable patterns of white matter asymmetry, with no significant group differences. These asymmetry patterns were consistent with those reported in previous fixel-based studies. These results suggest that white matter lateralization is preserved despite complete visceral reversal. The observed divergence between brain and visceral asymmetry patterns suggests that symmetry breaking in visceral laterality relies on distinct mechanisms.
完全性内脏反位（SIT）是一种罕见的情况，涉及胸腔和腹腔器官位置的完全反转，为研究内脏和大脑不对称之间的潜在关系提供了一个独特的模型。在本研究中，我们检查了21名SIT参与者与21名匹配的正常内脏位置（SO）对照者相比，白质不对称是否发生改变。该样本代表了迄今为止研究的最大一组SIT个体。使用基于固定点的分析，这是一种先进的扩散磁共振成像框架，我们比较了两组之间全脑的微观和宏观结构白质不对称性，特别评估了纤维密度和横截面积（FDC）。两组均显示出广泛但相当的白质不对称模式，无显著组间差异。这些不对称模式与先前基于固定点的研究报告的模式一致。这些结果表明，尽管内脏完全反转，白质偏侧化仍得以保留。观察到的大脑和内脏不对称模式之间的差异表明，内脏侧化中的对称性打破依赖于不同的机制。
