Department of Linguistics and Cognitive Science, University of Delaware, USA; Graduate Institute of Linguistics, National Taiwan University, Taiwan.
Graduate Institute of Linguistics, National Taiwan University, Taiwan; Department of Psychology, National Taiwan University, Taiwan; Graduate Institute of Brain and Mind Sciences, National Taiwan University, Taiwan; Neurobiology and Cognitive Neuroscience Center, National Taiwan University, Taiwan.
Brain Res. 2020 Jul 1;1738:146815. doi: 10.1016/j.brainres.2020.146815. Epub 2020 Mar 31.
The present study examined the hypothesis that left hemisphere (LH) equivalent language capabilities in the right hemisphere (RH) are inhibited in neurologically intact individuals by testing healthy young right-handers with a history of familial sinistrality (FS+, i.e. with at least one left handed biological relative), a population documented to show greater variability for RH language processing. Event-Related Potential (ERP) and split visual field presentation techniques were combined to assess LH- and RH- biased responses to syntactic category violations. In addition, a bilateral flanker task was used to measure inter-hemispheric inhibition ability in the same set of participants. Replicating prior findings, in addition to the LH-biased P600 grammaticality effect previously seen for right-handers in general, a fair amount, though not all, of FS + right-handers showed RH-biased P600 responses, leading to a reliable RH P600 grammaticality effect at the group level. Capitalizing on the variability of RH P600 responses, our results further revealed that reduced RH-biased P600 effects were reliably correlated with more effective RH inhibition (indexed by smaller reaction time differences between incongruent and neutral flankers presented to the RH via the left visual field). These results corroborated previous findings that the RH is capable of processing syntactic information in a manner qualitatively similar to that in the LH and further demonstrated that LH-equivalent processing in the RH as indexed by the P600 responses is modulated by RH inhibition, contributing to inter-individual variability in syntactic lateralization.
本研究检验了这样一个假设，即在神经健全的个体中，左半球（LH）在右半球（RH）中的等效语言能力受到抑制，为此我们测试了有家族左撇子史（FS+，即至少有一个左手的生物学亲属）的健康年轻右利手个体，该人群被证明在 RH 语言处理方面表现出更大的变异性。事件相关电位（ERP）和分视场呈现技术相结合，以评估对句法类别违反的 LH 和 RH 偏向反应。此外，还使用双侧侧翼任务来测量同一组参与者的半球间抑制能力。与先前的发现一致，除了先前一般右利手的 LH 偏向 P600 语法效应外，相当数量但并非全部的 FS+右利手表现出 RH 偏向 P600 反应，从而导致在群体水平上出现可靠的 RH P600 语法效应。利用 RH P600 反应的可变性，我们的结果进一步表明，RH 偏向 P600 效应的降低与更有效的 RH 抑制可靠相关（通过左视野向 RH 呈现不一致和中性侧翼之间的反应时间差异来衡量）。这些结果证实了先前的发现，即 RH 能够以与 LH 相似的方式处理句法信息，并且进一步表明，P600 反应所指示的 RH 中的 LH 等效处理受到 RH 抑制的调节，从而导致句法侧化的个体间变异性。
