Caldwell Hayley Bree
Cognitive and Systems Neuroscience Research Hub (CSN-RH), School of Justice and Society, University of South Australia Magill Campus, Magill, South Australia, Australia.
Ann Neurosci. 2022 Jan;29(1):62-70. doi: 10.1177/09727531211070538. Epub 2022 Feb 15.
It is currently accepted that sign languages and spoken languages have significant processing commonalities. The evidence supporting this often merely investigates frontotemporal pathways, perisylvian language areas, hemispheric lateralization, and event-related potentials in typical settings. However, recent evidence has explored beyond this and uncovered numerous modality-dependent processing differences between sign languages and spoken languages by accounting for confounds that previously invalidated processing comparisons and by delving into the specific conditions in which they arise. However, these processing differences are often shallowly dismissed as unspecific to language.
This review examined recent neuroscientific evidence for processing differences between sign and spoken language modalities and the arguments against these differences' importance. Key distinctions exist in the topography of the left anterior negativity (LAN) and with modulations of event-related potential (ERP) components like the N400. There is also differential activation of typical spoken language processing areas, such as the conditional role of the temporal areas in sign language (SL) processing. Importantly, sign language processing uniquely recruits parietal areas for processing phonology and syntax and requires the mapping of spatial information to internal representations. Additionally, modality-specific feedback mechanisms distinctively involve proprioceptive post-output monitoring in sign languages, contrary to spoken languages' auditory and visual feedback mechanisms. The only study to find ERP differences post-production revealed earlier lexical access in sign than spoken languages. Themes of temporality, the validity of an analogous anatomical mechanisms viewpoint, and the comprehensiveness of current language models were also discussed to suggest improvements for future research.
Current neuroscience evidence suggests various ways in which processing differs between sign and spoken language modalities that extend beyond simple differences between languages. Consideration and further exploration of these differences will be integral in developing a more comprehensive view of language in the brain.
目前人们普遍认为手语和口语在处理过程中有显著的共性。支持这一观点的证据通常仅在典型情况下研究额颞叶通路、颞周语言区域、半球侧化和事件相关电位。然而，最近的证据已经超越了这一点，通过考虑先前使处理比较无效的混杂因素，并深入研究它们出现的具体条件，发现了手语和口语之间许多依赖于模态的处理差异。然而，这些处理差异往往被简单地认为与语言无关而被忽视。
本综述研究了最近关于手语和口语模态处理差异的神经科学证据以及反对这些差异重要性的论点。在左前负波（LAN）的地形图以及事件相关电位（ERP）成分（如N400）的调制方面存在关键差异。典型口语处理区域也存在差异激活，例如颞叶区域在手语（SL）处理中的条件作用。重要的是，手语处理独特地招募顶叶区域来处理音系和句法，并且需要将空间信息映射到内部表征。此外，与口语的听觉和视觉反馈机制相反，特定于模态的反馈机制在很大程度上涉及手语中的本体感觉输出后监测。唯一一项发现生产后ERP差异的研究表明，手语中的词汇访问比口语更早。还讨论了时间性主题、类似解剖学机制观点的有效性以及当前语言模型的全面性，以建议未来研究的改进方向。
目前的神经科学证据表明，手语和口语模态在处理方式上存在多种差异，这些差异不仅仅是语言之间的简单差异。考虑和进一步探索这些差异对于形成更全面的大脑语言观至关重要。
