CONTRIBUTION OF NEURAL MEMORY CIRCUITS TO LANGUAGE

这个项目的长期目标是了解心理词汇的大脑基础，其中包含记忆的单词，以及心理语法，其中包含将词汇形式组合成更大的单词、短语和句子的规则。我们提出，词汇的记忆和使用是由颞叶回路控制的，而语法规则的获取和使用是由额叶/基底神经节回路控制的，而额叶/基底神经节回路则与运动、知觉和认知“技能”（如骑自行车）的学习和表达有关。因此，我们假设词汇和语法与不同的大脑系统相关联，每个系统都是域通用的，因为它既服务于非语言领域，也服务于语言领域。这种新颖的观点与两种主要的相互竞争的理论框架形成了对比。虽然我们认同传统双系统理论的观点，假设词汇和语法是由不同的系统服务的，但我们与这些理论不同，这些理论假设两种能力中的每一种都有专门的（特定领域的）组件。相反，当我们与单系统理论分享这两种能力是由域一般电路服务的观点时，我们与他们不同，他们将这两种能力联系到一个具有广泛解剖分布的单一系统。为了将我们的理论与其他两种理论区分开来，我们将探索不规则和规则单词转换的大脑基础，其中词汇和语法可以对比，而其他因素保持不变。不规则形式（例如，dig-dug）是从内存中检索的，而规则形式（例如，look- looking）需要后缀规则。我们预测并在初步研究中发现了不规则规则（词汇）、事实和颞叶回路之间的联系，以及不规则规则（语法）、技能和额/基底神经节回路之间的联系。单系统模型不能做出这组预测，传统的双系统理论也不能预测与事实和技能使用的联系。颞叶或额叶/基底神经节损伤的患者将被赋予任务，探索不规则和规则的过去时屈折、复数屈折（老鼠、蜜蜂）和衍生形态（庄严、尴尬）的产生和判断，以及事实和技能使用的测量。我们的具体目标是通过探索不规则规则和规则之间以及事实和技能之间的双重分离来验证三个假设：(1)词汇与颞叶回路有关，语法与额叶/基底神经节回路有关。(2)这些电路也分别服务于事实使用和技能使用。(3)基底神经节在运动活动和语法规则使用中起着类似的作用。

The long-term objective of this project is to understand the brain bases of the mental lexicon, which contains memorized words, and the mental grammar, which contains rules that combine lexical forms into larger words, phrases, and sentences. We propose that the memorization and use of words is subserved by temporal-lobe circuits previously implicated in the learning and use of fact knowledge, whereas the acquisition and use of grammatical rules is subserved by frontal/basal-ganglia circuits previously implicated in the learning and expression of motor, perceptual, and cognitive "skills," such as riding a bicycle. Thus we posit that lexicon and grammar are linked to distinct brain systems, each of which is domain-general in that it subserves non-language as well as language domains. This novel view contrasts with the two main competing theoretical frameworks. Although we share the perspective of traditional dual-system theories in positing that lexicon and grammar are subserved by distinct systems, we diverge from these theories where they assume components dedicated (domain-specific) to each of the two capacities. Conversely, while we share with single-system theories the view that the two capacities are subserved by domain-general circuitry, we diverge from them where they link both capacities to a single system with broad anatomic distribution. To distinguish our theory from the other two, we will probe the brain bases of irregular and regular word transformations, in which lexicon and grammar can be contrasted, while other factors are held constant. Irregular forms (e.g., dig-dug) are retrieved from memory, whereas regular forms (e.g., look-looked) require a suffixation rule. We predict, and have found in our preliminary studies, links among irregulars (lexicon), facts, and temporal- lobe circuits, and among regulars (grammar), skills, and frontal/basal-ganglia circuits. Single-system models do not make this set of predictions, and traditional dual-system theories do not predict the links with fact and skill use. Patients with either temporal-lobe or frontal/basal-ganglia damage will be given tasks probing the production and judgment of irregular and regular past tense inflection, plural inflection (mice, bees), and derivational morphology (solemnity, awkwardness), as well as measures of fact and skill use. Our specific aims are to test three hypotheses by probing for double dissociations between irregulars and regulars, and between facts and skills: (1) Lexicon is linked to temporal-lobe circuits, and grammar to frontal/basal-ganglia circuits. (2) These circuits also subserve fact and skill use, respectively. (3) The basal ganglia play a similar role in motor activity and grammatical rule use.