CONTRIBUTION OF NEURAL MEMORY CIRCUITS TO LANGUAGE

这个项目的长期目标是理解心理词典和心理语法的大脑基础，心理词典包含记忆的单词，心理语法包含将词汇形式组合成更大的单词、短语和句子的规则。我们认为，单词的记忆和使用受到先前与事实知识的学习和使用有关的颞叶电路的辅助，而语法规则的获得和使用则由额叶/基底节电路辅助，而额叶/基底节电路先前与运动、知觉和认知“技能”的学习和表达有关，例如骑自行车。因此，我们假设词汇和语法与不同的大脑系统相联系，每个系统都是领域通用的，因为它既从属于非语言领域，也从属于语言领域。这一新颖的观点与两种主要的相互竞争的理论框架形成了鲜明对比。虽然我们认同传统的双重系统理论的观点，即词汇和语法是由不同的系统来服务的，但我们与这些理论不同，这些理论假设词汇和语法的组成部分专门用于(领域特定的)这两种能力。相反，虽然我们同意单系统理论的观点，即这两种能力受域通用电路的影响，但我们与它们背道而驰，因为它们将两种能力链接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，在这种转换中，词汇和语法可以进行对比，而其他因素保持不变。不规则形式(例如，挖掘式)从存储器中检索，而规则形式(例如，外观)需要后缀规则。我们预测，并在我们的初步研究中发现，在不规则(词汇)、事实和颞叶回路之间，以及在正规(语法)、技能和额叶/基底节回路之间存在联系。单一系统模型不会做出这一组预测，传统的双重系统理论也不会预测与事实和技能使用的联系。颞叶或额叶/基底节受损的患者将被布置任务，探索不规则和规则的过去时屈折、复数屈折(老鼠、蜜蜂)和派生形态(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非正规和正规之间以及事实和技能之间的双重分离来检验三个假说：(1)词汇与颞叶回路有关，语法与额叶/基底节回路有关。(2)这些回路还分别辅助事实和技能的使用。(3)基底节在运动活动和语法规则使用中起着相似的作用。

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.