The core symptoms of schizophrenia spectrum disorders (SSD) include abnormal semantic processing which may rely on the ventral language stream of the human brain. Thus, structural disruption of the ventral language stream may play an important role in semantic deficits observed in SSD patients. Therefore, we compared white matter tract integrity in SSD patients and healthy controls using diffusion tensor imaging combined with probabilistic fiber tractography. For the ventral language stream, we assessed the inferior fronto-occipital fasciculus [IFOF], inferior longitudinal fasciculus, and uncinate fasciculus. The arcuate fasciculus and corticospinal tract were used as control tracts. In SSD patients, the relationship between semantic processing impairments and tract integrity was analyzed separately. Three-dimensional tract reconstructions were performed in 45/44 SSD patients/controls ("Bern sample") and replicated in an independent sample of 24/24 SSD patients/controls ("Basel sample"). Multivariate analyses of fractional anisotropy, mean, axial, and radial diffusivity of the left IFOF showed significant differences between SSD patients and controls (p(FDR-corr) < 0.001, ηp2 = 0.23) in the Bern sample. Axial diffusivity (AD) of the left UF was inversely correlated with semantic impairments (r = -0.454, p(FDR-corr) = 0.035). In the Basel sample, significant group differences for the left IFOF were replicated (p < .01, ηp2 = 0.29), while the correlation between AD of the left IFOF and semantic processing decline (r = -0.376, p = .09) showed a statistical trend. No significant effects were found for the dorsal language stream. This is direct evidence for the importance of the integrity of the ventral language stream, in particular the left IFOF, in semantic processing deficits in SSD.

中文翻译：

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精神分裂症谱系障碍中额枕下束内的解剖完整性和语义处理缺陷

精神分裂症谱系障碍 (SSD) 的核心症状包括异常语义处理，这可能依赖于人脑的腹侧语言流。因此，腹侧语言流的结构破坏可能在 SSD 患者中观察到的语义缺陷中发挥重要作用。因此，我们使用扩散张量成像结合概率纤维束成像比较了 SSD 患者和健康对照的白质束完整性。对于腹侧语言流，我们评估了下额枕束 [IFOF]、下纵束和钩状束。弓状束和皮质脊髓束用作对照束。在 SSD 患者中，语义处理障碍与管道完整性之间的关系被单独分析。在 45/44 名 SSD 患者/对照（“伯尔尼样本”）中进行了三维道重建，并在 24/24 名 SSD 患者/对照（“巴塞尔样本”）的独立样本中进行了复制。伯尔尼样本中左侧 IFOF 的分数各向异性、平均、轴向和径向扩散率的多变量分析显示，SSD 患者和对照组之间存在显着差异（p(FDR-corr) < 0.001, ηp2 = 0.23）。左 UF 的轴向扩散率 (AD) 与语义障碍呈负相关 (r = -0.454, p(FDR-corr) = 0.035)。在巴塞尔样本中，重复了左侧 IFOF 的显着组差异（p < .01，ηp2 = 0.29），而左侧 IFOF 的 AD 与语义处理下降之间的相关性（r = -0.376，p = .09）显示统计趋势。没有发现对背语流的显着影响。这是腹侧语言流完整性的重要性的直接证据，尤其是左 IFOF，在 SSD 的语义处理缺陷中。