ABSTRACT

The left hemisphere is dominant for language in most people, but lateralization strength varies between different tasks and individuals. A large body of literature has shown that handedness is associated with lateralization: left handers have weaker language lateralization on average, and a greater incidence of atypical (right hemisphere) lateralization; but typically, these studies have relied on a single measure of language lateralization. Here we consider the relationships between lateralization for two different language tasks. We investigated the influence of handedness on lateralization using functional transcranial Doppler sonography (fTCD), using an existing dataset (N = 151 adults, 21 left handed). We compared a speech production task (word generation) and a semantic association task. We demonstrated stronger left-lateralization for word generation than semantic association; and a moderate correlation between laterality indices for the two tasks (r = 0.59). Laterality indices were stronger for right than left handers, and left handers were more likely than right handers to have atypical (right hemisphere) lateralization or inconsistent lateralization between the two tasks. These results add to our knowledge of individual differences in lateralization and support the view that language lateralization is multifactorial rather than unitary.

摘要

在大多数人中，左半球的语言占主导地位，但不同任务和个体之间的侧向化强度不同。大量文献表明，惯用手与偏侧化有关：左撇子平均语言偏侧化较弱，非典型（右半球）偏侧化的发生率更高；但通常，这些研究依赖于单一的语言侧化测量。在这里，我们考虑两种不同语言任务的横向化之间的关系。我们使用现有的数据集（N = 151 名成人，21 名左撇子），使用功能性经颅多普勒超声 (fTCD) 研究了惯用手对偏侧化的影响。我们比较了语音生成任务（单词生成）和语义关联任务。我们展示了比语义关联更强的单词生成左偏化；以及两个任务的偏侧指数之间的中等相关性（r = 0.59）。右撇子的侧向指数比左撇子强，左撇子比右撇子更有可能在两项任务之间出现非典型（右半球）侧化或不一致的侧化。这些结果增加了我们对侧化个体差异的认识，并支持语言侧化是多因素而非单一的观点。并且左撇子比右撇子更有可能在两项任务之间发生非典型（右半球）侧化或不一致的侧化。这些结果增加了我们对侧化个体差异的认识，并支持语言侧化是多因素而非单一的观点。并且左撇子比右撇子更有可能在两项任务之间发生非典型（右半球）侧化或不一致的侧化。这些结果增加了我们对侧化个体差异的认识，并支持语言侧化是多因素而非单一的观点。