Nagata S I, Uchimura K, Hirakawa W, Kuratsu J I
Department of Neurosurgery, Faculty of Medicine, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima City, Japan, 890-8520.
AJNR Am J Neuroradiol. 2001 May;22(5):985-91.
Various methods for evaluating the lateralization of linguistic function using functional MR imaging have been proposed. However, the optimal method remains controversial. The purpose of this study was not only to establish a method for quantitatively evaluating the lateralization of linguistic function but also to evaluate its optimality.
Internal speech tasks were measured by functional MR imaging in 17 healthy adult volunteers by use of z scores. The laterality index (LI) was calculated first by a previously reported method and second by our newly designed method, in which we investigated the correlation between the z scores and the number of activated pixels in the regions of interest; that is, we made scatter diagrams (z scores versus number of activated pixels). To obtain detailed information, we searched a regression function that fit the scatter diagrams well.
We found the number of activated pixels was proportional to (1/z score)(4) and the correlation coefficient was very high. Each hemisphere showed an original proportional constant. Our newly designed LI was calculated from these two constants and was found to be a fixed value. In contrast, the reported LI varied with the z score. We found our LI differed in robustness and reproducibility from the reported LI.
Our LI method proved more optimal than the reported LI. The lateralization of linguistic function can be evaluated quantitatively using our new LI method.
已经提出了多种使用功能磁共振成像评估语言功能偏侧化的方法。然而，最佳方法仍存在争议。本研究的目的不仅是建立一种定量评估语言功能偏侧化的方法，还评估其最优性。
对17名健康成年志愿者使用功能磁共振成像测量内部言语任务，采用z分数。首先通过先前报道的方法计算偏侧化指数（LI），其次通过我们新设计的方法计算，在新方法中我们研究了感兴趣区域中z分数与激活像素数量之间的相关性；即，我们制作了散点图（z分数与激活像素数量）。为了获得详细信息，我们寻找了一个能很好拟合散点图的回归函数。
我们发现激活像素数量与（1/z分数）⁴成正比，且相关系数非常高。每个半球都显示出一个原始比例常数。我们新设计的LI由这两个常数计算得出，并且发现它是一个固定值。相比之下，报道的LI随z分数而变化。我们发现我们的LI在稳健性和可重复性方面与报道的LI不同。
我们的LI方法被证明比报道的LI更优。可以使用我们新的LI方法定量评估语言功能的偏侧化。
