Max Planck Institute for Psycholinguistics, P.O. Box 310, NL-6500 AH Nijmegen, The Netherlands.
Brain Lang. 2012 Feb;120(2):83-95. doi: 10.1016/j.bandl.2010.08.003. Epub 2010 Oct 12.
In this paper we examine the neurobiological correlates of syntax, the processing of structured sequences, by comparing FMRI results on artificial and natural language syntax. We discuss these and similar findings in the context of formal language and computability theory. We used a simple right-linear unification grammar in an implicit artificial grammar learning paradigm in 32 healthy Dutch university students (natural language FMRI data were already acquired for these participants). We predicted that artificial syntax processing would engage the left inferior frontal region (BA 44/45) and that this activation would overlap with syntax-related variability observed in the natural language experiment. The main findings of this study show that the left inferior frontal region centered on BA 44/45 is active during artificial syntax processing of well-formed (grammatical) sequence independent of local subsequence familiarity. The same region is engaged to a greater extent when a syntactic violation is present and structural unification becomes difficult or impossible. The effects related to artificial syntax in the left inferior frontal region (BA 44/45) were essentially identical when we masked these with activity related to natural syntax in the same subjects. Finally, the medial temporal lobe was deactivated during this operation, consistent with the view that implicit processing does not rely on declarative memory mechanisms that engage the medial temporal lobe. In the context of recent FMRI findings, we raise the question whether Broca's region (or subregions) is specifically related to syntactic movement operations or the processing of hierarchically nested non-adjacent dependencies in the discussion section. We conclude that this is not the case. Instead, we argue that the left inferior frontal region is a generic on-line sequence processor that unifies information from various sources in an incremental and recursive manner, independent of whether there are any processing requirements related to syntactic movement or hierarchically nested structures. In addition, we argue that the Chomsky hierarchy is not directly relevant for neurobiological systems.
在本文中，我们通过比较人工语言和自然语言句法的 fMRI 结果来研究句法（结构化序列的处理）的神经生物学相关性。我们在形式语言和可计算性理论的背景下讨论了这些以及类似的发现。我们在 32 名健康荷兰大学生中使用了一个简单的右线性统一语法，采用隐式人工语法学习范式（这些参与者的自然语言 fMRI 数据已经获得）。我们预测，人工句法处理将涉及左侧下额叶区域（BA44/45），并且这种激活将与自然语言实验中观察到的与句法相关的可变性重叠。本研究的主要发现表明，BA44/45 中心的左侧下额叶区域在处理形式良好（语法）的序列时是活跃的，与局部子序列的熟悉度无关。当存在句法违规且结构统一变得困难或不可能时，该区域的活动程度更大。当我们用相同受试者的自然句法相关活动对左侧下额叶区域（BA44/45）中的这些效应进行掩蔽时，与人工句法相关的效应基本相同。最后，内侧颞叶在该操作过程中失活，这与内隐处理不依赖于参与内侧颞叶的陈述性记忆机制的观点一致。在最近的 fMRI 发现的背景下，我们提出了这样一个问题，即布罗卡区（或亚区）是否与句法移动操作或层次嵌套非相邻依赖关系的处理特别相关。在讨论部分，我们得出的结论是并非如此。相反，我们认为左侧下额叶区域是一种通用的在线序列处理器，它以递增和递归的方式统一来自各种来源的信息，而与是否存在任何与句法移动或层次嵌套结构相关的处理要求无关。此外，我们认为乔姆斯基层次结构与神经生物学系统没有直接关系。
