Rutten G J M, Ramsey N F, van Rijen P C, Alpherts W C, van Veelen C W M
Department of Neurosurgery, University Medical Center Utrecht, The Netherlands.
Neuroimage. 2002 Sep;17(1):447-60. doi: 10.1006/nimg.2002.1196.
Due to the reported variability of the language laterality index (LI) across fMRI studies, reliable distinction between patients with unilateral and mixed language dominance is currently not possible, preventing clinical implementation of fMRI as a replacement for the invasive Wada test. Variability of the LI may be related to differences in experimental and control tasks, and statistical methodology. The goal of this study was to improve detection power of fMRI for hemispheric language dominance by using a combined analysis of four different language tasks (CTA), that has previously shown more reliable and robust Lls in groups of normal volunteers than individual task analyses (see Ramsey et al). The CTA targets brain areas that are common to different language tasks, thereby focusing on areas that are critical for language processing. Further advantage of the CTA is that it is relatively independent of specific task and control conditions. 18 patients with typical (i.e., left-sided, n = 11) and atypical (i.e., right-sided or mixed, respectively, n = 3 and n = 4) language dominance according to the Wada test underwent fMRI (groups respectively denoted as WadaL, WadaR, and WadaM patients). Statistical methodology (including thresholding of activity maps) was fixed to assure a user-independent approach. CTA yielded better results than any of the individual task analyses: it was more robust (on average 2.5 times more brain activity was detected due to its higher statistical power) and more reliable (concordance for WadaL, WadaM and WadaR patients was respectively 10/11 (91%), 3/4 (75%), and 2/3 patients (67%)). Overall, a significant correlation was observed between frontal and temporoparietal LIs. Remarkably, brain activity for WadaM patients was significantly lower than for WadaL or WadaR patients, and a dissociation in lateralization was observed between frontal (right-sided) and temporoparietal (left-sided) activity in three of four patients. Of the individual task analyses, the verb generation task yielded best results for patients with unilateral language dominance (same concordance as CTA). However, in contrast to CTA results, the verb generation task was unable to identify WadaM patients (concordance in one of four patients). In conclusion, the CTA is a promising approach for clinical implementation of fMRI for the prediction of hemispheric language dominance.
由于功能磁共振成像（fMRI）研究中报告的语言偏侧性指数（LI）存在变异性，目前无法可靠地区分单侧语言优势和混合语言优势的患者，这使得fMRI无法在临床上替代侵入性的Wada测试。LI的变异性可能与实验和对照任务以及统计方法的差异有关。本研究的目的是通过对四种不同语言任务进行联合分析（CTA）来提高fMRI检测半球语言优势的能力，此前在正常志愿者群体中，这种联合分析比单个任务分析显示出更可靠、更稳定的LI（见拉姆齐等人的研究）。CTA针对不同语言任务共有的脑区，从而聚焦于对语言处理至关重要的区域。CTA的另一个优势是它相对独立于特定的任务和对照条件。18名根据Wada测试具有典型（即左侧，n = 11）和非典型（即分别为右侧或混合，n = 3和n = 4）语言优势的患者接受了fMRI检查（这些组分别表示为WadaL、WadaR和WadaM患者）。统计方法（包括活动图的阈值设定）是固定的，以确保采用独立于用户的方法。CTA产生的结果比任何单个任务分析都要好：它更稳定（由于其更高的统计效力，平均检测到的脑活动多2.5倍）且更可靠（WadaL、WadaM和WadaR患者的一致性分别为10/11（91%）、3/4（75%）和2/3患者（67%））。总体而言，观察到额叶和颞顶叶LI之间存在显著相关性。值得注意的是，WadaM患者的脑活动明显低于WadaL或WadaR患者，并且在四名患者中的三名患者中观察到额叶（右侧）和颞顶叶（左侧）活动在侧化方面存在分离。在单个任务分析中，动词生成任务对单侧语言优势患者产生了最佳结果（一致性与CTA相同）。然而，与CTA结果不同的是，动词生成任务无法识别WadaM患者（四名患者中的一名患者一致）。总之，CTA是一种很有前景的方法，可用于fMRI在临床上预测半球语言优势。
