Medical Research Council Cognition and Brain Sciences Unit, Cambridge CB2 7EF, United Kingdom.
Proc Natl Acad Sci U S A. 2010 Oct 5;107(40):17439-44. doi: 10.1073/pnas.1000531107. Epub 2010 Sep 20.
Emerging evidence from neuroimaging and neuropsychology suggests that human speech comprehension engages two types of neurocognitive processes: a distributed bilateral system underpinning general perceptual and cognitive processing, viewed as neurobiologically primary, and a more specialized left hemisphere system supporting key grammatical language functions, likely to be specific to humans. To test these hypotheses directly we covaried increases in the nonlinguistic complexity of spoken words [presence or absence of an embedded stem, e.g., claim (clay)] with variations in their linguistic complexity (presence of inflectional affixes, e.g., play+ed). Nonlinguistic complexity, generated by the on-line competition between the full word and its onset-embedded stem, was found to activate both right and left fronto-temporal brain regions, including bilateral BA45 and -47. Linguistic complexity activated left-lateralized inferior frontal areas only, primarily in BA45. This contrast reflects a differentiation between the functional roles of a bilateral system, which supports the basic mapping from sound to lexical meaning, and a language-specific left-lateralized system that supports core decompositional and combinatorial processes invoked by linguistically complex inputs. These differences can be related to the neurobiological foundations of human language and underline the importance of bihemispheric systems in supporting the dynamic processing and interpretation of spoken inputs.
神经影像学和神经心理学的新证据表明，人类言语理解涉及两种类型的神经认知过程：一种是支持一般感知和认知处理的分布式双侧系统，被视为神经生物学上的主要系统，另一种是支持关键语法语言功能的更专门的左侧半球系统，可能是人类特有的。为了直接检验这些假设，我们将口语词汇的非语言复杂性（例如，是否存在嵌入的词干，如 claim(clay))的增加与语言复杂性（例如，屈折后缀的存在，如 play+ed)的变化进行了共变。在线竞争产生的非语言复杂性，全词与其起始嵌入词干之间的在线竞争，激活了双侧额颞脑区，包括双侧 BA45 和 -47。语言复杂性仅激活左侧额下回区域，主要在 BA45。这种对比反映了一个双侧系统的功能角色的分化，该系统支持从声音到词汇意义的基本映射，以及一个语言特异性的左侧系统，支持由语言复杂输入引发的核心分解和组合过程。这些差异可以与人类语言的神经生物学基础相关联，并强调了双半球系统在支持口语输入的动态处理和解释方面的重要性。
