双侧大脑侧度对单词生成的可靠性:谁被留在中间?

Imaging neuroscience (Cambridge, Mass.) Pub Date : 2025-08-07 eCollection Date: 2025-01-01 DOI:10.1162/IMAG.a.102
Robin Gerrits, Guy Vingerhoets
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摘要

虽然词的产生被认为是一种强烈的左半球偏侧功能,但其大脑的不对称性因人而异。最流行的确定半球优势的方法是通过比较两个半球之间的大脑活动来计算侧性指数(LI)。大的LIs可以很容易地分类为左侧或右侧显性,但对于如何治疗表明(接近)对称活动的双侧LIs没有共识。由于缺乏可靠性,解释非常小的LIs的问题一直存在,这源于系统调查这些罕见病例(通常≤10%的样本)的挑战。为了解决这一差距,我们进行了两项研究,调查了功能性经颅多普勒超声(fTCDS)(一种基于超声测量脑血流速度的方法)获得的双侧LIs的可靠性和跨方法普遍性。在研究1中,我们比较了在两个会话的字母口头流利fTCDS任务中,双侧LIs (n=35)和清晰侧化LIs (n=32)的再现性。虽然左侧分类的可重复性高(97%重复),但双侧分类的可重复性较差(51%重复)。事实上,左右两种分类比将双侧li的参与者分配到单独的类别产生了更可靠的结果(80%重复)。研究2评估了fTCDS的小不对称性是否扩展到其他确定大脑侧性的仪器(视觉半视野法和功能磁共振成像)。被fTCDS一致归类为双侧的参与者(n=18)在这些其他方法中也表现出减少的群体水平不对称性。基于这些结果,我们认为li反映了特殊的大脑不对称性、状态相关波动和测量噪声的组合。我们的研究结果还表明,尽管真正的半球等效可能极其罕见,但一部分人的单词生成神经系统本质上是弱偏侧化的。最后,我们提出了在临床和研究背景下对不对称进行分类的建议。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
The reliability of bilateral cerebral laterality for word generation: Who is left in the middle?

Although word production is considered a strongly left hemispheric lateralized function, its cerebral asymmetry varies among individuals. The most popular way of determining hemisphere dominance is to calculate a laterality index (LI) by comparing brain activity between the two hemispheres. Large LIs can readily be classified as left or right dominant, but there is no consensus on how to treat bilateral LIs indicating (near) symmetrical activity. The problem with interpreting very small LIs is perpetuated by a lack of reliability, stemming from the challenge of systematically investigating these uncommon cases (usually ≤ 10% of a sample). To address this gap, we performed two studies that investigated the reliability and across-methods generalizability of bilateral LIs obtained from functional transcranial Doppler sonography (fTCDS)-an ultrasound-based approach that measures cerebral blood flow velocity. In Study 1, we compared reproducibility of bilateral LIs (n=35) and clearly lateralized LIs (n=32) during a letter verbal fluency fTCDS task across two sessions. While left-lateralized classifications were highly replicable (97% reproduced), poorer reproducibility was observed for bilateral classifications (51% reproduced). In fact, dichotomous left-right categorization yielded more reliable outcomes than assigning participants with bilateral LIs to a separate category (80% reproduced). Study 2 assessed whether small fTCDS asymmetry extended to other instruments for determining cerebral laterality (visual half-field method and fMRI). Participants consistently classified as bilateral by fTCDS (n=18) also exhibited reduced group-level asymmetry in these other methods. Based on these results, we suggest that LIs reflect a combination of idiosyncratic cerebral asymmetry, state-dependent fluctuations, and measurement noise. Our findings also indicate that a subset of the population has a neural system for word production that is inherently weakly lateralized, although true hemispheric equivalence is likely extremely rare. Finally, we offer recommendations for classifying asymmetry in clinical and research contexts.

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