Leroux Elise, Delcroix Nicolas, Dollfus Sonia
CHU de Caen, Service de Psychiatrie, Centre Esquirol, Caen F-14000, France; CNRS, UMR 6301 ISTCT, ISTS Team, GIP CYCERON, Bd Henri Becquerel, BP5229, F-14074 Caen cedex, France.
CNRS, UMS 3408, GIP CYCERON, Bd Henri Becquerel, BP5229, F-14074 Caen cedex, France.
Schizophr Res. 2015 Jun;165(1):30-7. doi: 10.1016/j.schres.2015.03.028. Epub 2015 Apr 11.
It has been suggested that the degree of hemispheric specialization (HS) depends on the structural connectivity between the two hemispheres, that is to say the corpus callosum (CC). Studies, performed only on healthy participants, investigated this anatomo-functional relationship. Nevertheless, it has never been studied in schizophrenia. We therefore propose to study the anatomo-functional relationships between the integrity of interhemispheric connectivity and leftward functional lateralization for language in patients with schizophrenia compared with healthy participants, driven by a multimodal approach combining fMRI and DTI-based fiber tractography. We hypothesized that reduced leftward functional lateralization for language in patients with schizophrenia could be related to a callosal hypoconnectivity.
Seventeen patients based on the DSM-IV, and 17 controls were included. The functional laterality index and interhemispheric diffusion values between homologue temporal regions, belonging to the language network, were individually extracted in order to study the anatomo-functional relationships.
In the patients, higher mean and radial diffusivity (RD) values (thicker myelin sheaths) were associated with less leftward lateralization. In contrast, the controls presented higher RD values and lower fractional anisotropy values (axonal loss) with more leftward lateralization.
Our study revealed a relationship between the CC and the HS for language, but did not provide evidence clarifying the direction of the relationship between callosal connectivity and functional lateralization for language. In particular, the present findings showed that the loss of integrity in interhemispheric callosal fibers was associated with reduced leftward cerebral dominance for language in patients with schizophrenia.
有人提出，半球特化（HS）程度取决于两个半球之间的结构连通性，即胼胝体（CC）。此前的研究仅针对健康参与者，探讨了这种解剖学与功能之间的关系。然而，从未在精神分裂症患者中进行过此类研究。因此，我们建议采用功能磁共振成像（fMRI）和基于扩散张量成像（DTI）的纤维束成像相结合的多模态方法，研究精神分裂症患者与健康参与者相比，半球间连通性完整性与语言功能左向侧化之间的解剖学与功能关系。我们假设，精神分裂症患者语言功能左向侧化减弱可能与胼胝体连接性降低有关。
纳入17例符合《精神疾病诊断与统计手册第四版》（DSM-IV）标准的患者和17名对照者。分别提取属于语言网络的同源颞叶区域之间的功能侧化指数和半球间扩散值，以研究解剖学与功能关系。
在患者中，较高的平均扩散率和径向扩散率（RD）值（髓鞘较厚）与较少的左向侧化相关。相比之下，对照组的RD值较高，分数各向异性值较低（轴突损失），左向侧化程度更高。
我们的研究揭示了胼胝体与语言半球特化之间的关系，但未提供证据阐明胼胝体连接性与语言功能侧化之间关系的方向。特别是，目前的研究结果表明，半球间胼胝体纤维完整性的丧失与精神分裂症患者语言功能左脑优势减弱有关。
