Westerhausen René, Huster René J, Kreuder Frank, Wittling Werner, Schweiger Elisabeth
Department of Biological and Medical Psychology, University of Bergen Jonas Lies vei 91 N-5009 Bergen, Norway.
Neuroimage. 2007 Aug 15;37(2):379-86. doi: 10.1016/j.neuroimage.2007.05.047. Epub 2007 Jun 7.
The functional integrity of the corticospinal tract (CST) is of crucial importance for fine and independent finger movement. Therefore, it has been frequently speculated that interhemispheric asymmetries in this tract might be associated with handedness. The objective of the present study was to examine this proposed relationship, by studying the effects of handedness on macro- and microstructural properties of the CST. For this purpose, 30 consistently left and 30 consistently right-handed participants of either sex were examined applying a combination of anatomical T1-weighted and diffusion-tensor (DTI) MR imaging. In an automated procedure and based on white matter probability maps as well as on DTI fibre direction information, the left and right hemispheric CST was segmented in the individual brain. Focussing the analysis on the posterior limb of the internal capsule, the size as well as two DTI parameters (mean diffusion and fractional anisotropy) was determined. Although the statistical analysis revealed substantial CST asymmetries regarding size, mean diffusion, and anisotropy, neither of these metrics showed a significant hemisphere-by-handedness interaction. From this it was concluded that handedness might be related to motorcortical asymmetries which seem not to be directly reflected in the corticospinal fibre tract characteristics.
皮质脊髓束（CST）的功能完整性对于精细且独立的手指运动至关重要。因此，人们经常推测该束的半球间不对称可能与利手性有关。本研究的目的是通过研究利手性对CST宏观和微观结构特性的影响来检验这一假设关系。为此，对30名始终惯用左手和30名始终惯用右手的男女参与者进行了研究，采用了解剖学T1加权和扩散张量（DTI）磁共振成像相结合的方法。在一个自动化程序中，基于白质概率图以及DTI纤维方向信息，在个体大脑中对左右半球的CST进行分割。将分析聚焦于内囊后肢，确定其大小以及两个DTI参数（平均扩散率和各向异性分数）。尽管统计分析显示在大小、平均扩散率和各向异性方面CST存在显著的不对称性，但这些指标均未显示出显著的半球×利手性交互作用。由此得出结论，利手性可能与运动皮质不对称有关，而运动皮质不对称似乎并未直接反映在皮质脊髓纤维束特征中。
