Westerhausen René, Kreuder Frank, Dos Santos Sequeira Sarah, Walter Christof, Woerner Wolfgang, Wittling Ralf Arne, Schweiger Elisabeth, Wittling Werner
Center for Neuropsychological Research, University of Trier, Johanniterufer 15, D-54290 Trier, Germany.
Brain Res Cogn Brain Res. 2004 Nov;21(3):418-26. doi: 10.1016/j.cogbrainres.2004.07.002.
The corpus callosum (CC) represents the major commissural tract connecting the two cerebral hemispheres and is supposed to play crucial integrative role in functional hemispheric specialization. The present study examined whether interindividual variations in macro- and microstructure of the human CC are associated with handedness and gender. Therefore, a combined diffusion-tensor (DTI) and high-resolution morphological MRI study was performed on 34 right- and 33 left-handed subjects of both sexes. The mid-sagittal surface areas and quantitative measures of molecular diffusion (relative anisotropy, mean diffusion) of the total CC and its subregions (genu, truncus, posterior third) were determined. Analysis revealed a larger total callosal area in right- as compared to left-handed subjects and in males as compared to females. Throughout all callosal subregions, anisotropy was found to be increased in left-handed as well as in male subjects, while the mean diffusion was diminished only in left-handers. For the posterior third of the CC, a significant negative correlation (r=-0.34) between anisotropy and area was detected in right-handed subjects. Summarized, significant alterations in the molecular diffusion and in the size of the CC with respect to gender and handedness were revealed in the present study. These findings can be interpreted as handedness- and gender-related differences in macro- and microstructure of the callosal pathways. It was demonstrated that the inspection of the callosal microstructure using DTI yields empirical evidence on interhemispheric connectivity that goes well beyond the information revealed by anatomical measurements alone. Thus, DTI has proven to be a useful additional method in cognitive neuroscience.
胼胝体（CC）是连接两个大脑半球的主要连合纤维束，被认为在功能性半球特化中发挥关键的整合作用。本研究探讨了人类CC的宏观和微观结构的个体差异是否与利手和性别有关。因此，对34名右利手和33名左利手的男女受试者进行了扩散张量成像（DTI）和高分辨率形态学MRI联合研究。测定了总CC及其亚区（膝部、体部、后三分之一）的矢状中表面积和分子扩散的定量指标（相对各向异性、平均扩散率）。分析显示，与左利手受试者相比，右利手受试者的胼胝体总面积更大；与女性相比，男性的胼胝体总面积更大。在所有胼胝体亚区中，发现左利手受试者和男性受试者的各向异性增加，而平均扩散率仅在左利手受试者中降低。对于CC的后三分之一，在右利手受试者中检测到各向异性与面积之间存在显著负相关（r=-0.34）。总之，本研究揭示了CC在分子扩散和大小方面与性别和利手有关的显著变化。这些发现可以解释为胼胝体通路在宏观和微观结构上与利手和性别相关的差异。结果表明，使用DTI检查胼胝体微观结构可提供关于半球间连接性的经验证据，这远远超出了仅通过解剖学测量所揭示的信息。因此，DTI已被证明是认知神经科学中一种有用的辅助方法。
