Age of acquisition effects on sign language development and brain processing

项目摘要 习得年龄对手语发育和脑加工的影响 母语习得年龄对语言能力和大脑语言有着终生的影响 正在处理。出生时失聪的婴儿通常在不同的年龄段第一次体验语言，这是因为他们无法 感知口语，直到年纪较大时才接触手语。我们很自然地使用这个 母语AOA的发生变异来模拟语言的关键期。在一系列研究中，询问什么是 语言和神经的关键时期的相关因素可能是。我们检验了这一假设，即 大脑语言系统是语言经验之间相互作用的产物 以及后天的大脑发育。我们用两种发展范式来检验这一假设， 回溯和纵向。这些回溯性研究测试了ASL习得完全的聋人。 这些研究调查了1-8岁之间的母语AOA效应是否与水平呈线性关系 获得的句法复杂性，神经语言加工的位置和分布，以及特征 背侧和腹侧白质束。这项纵向研究测试了ASL 习得可能是持续的，其L1 AOA开始于婴儿期，或在儿童早期或晚期。这个 青少年每年进行一次连续三年的测试，实验内容与成人相同 学习。语言实验是为了测试ASL句子的理解和产生 结构作为句法复杂性的函数。实验范式是从句到图 匹配、引出模仿、句法启动和自发产生。神经语言学实验 使用fMRI研究句子和词汇的加工。脑结构研究使用DTI来研究 背侧和腹侧白质束发育。如果大脑语言系统需要语言经验 在出生后早期大脑发育成为完全功能的过程中，句法发展水平应该 与神经语言处理在大脑中的分布和位置以及与 大脑语言网络中白质束发育的稳健性。

Project Summary Age of acquisition effects on sign language development and brain processing Age of first-language age of acquisition, L1 AoA, has lifelong effects on language abilities and brain language processing. Infants born deaf often first experience language at a variety of ages due to an inability to perceive spoken language and not being exposed to sign language until older ages. We use this naturally occurring variation in L1 AoA to model the critical period for language. In a series of studies, ask what the language and neural correlates of the critical period might be. We test the hypothesis the organization of the brain language system is an emergent property arising from interactive effects between language experience and acquisition and post-natal brain growth. We test the hypothesis with two developmental paradigms, retrospective and longitudinal. The retrospective studies test deaf adults whose ASL acquisition is complete. These studies investigate whether L1 AoA effects between the ages of 1-8 are linear with respect to the level of syntactic complexity acquired, the locus and distribution of neurolinguistic processing, and characteristics of the dorsal and ventral white matter tracts. The longitudinal studies test deaf adolescents whose ASL acquisition may be ongoing and whose L1 AoA began in infancy, or in early or late childhood. The adolescents are tested annually for three consecutive years with same experiments as used in the adult study. The language experiments are designed to test the comprehension and production of ASL sentence structure as a function of syntactic complexity. The experimental paradigms are sentence-to-picture matching, elicited imitation, syntactic priming, and spontaneous production. The neurolinguistic experiments use fMRI to investigate sentence and lexical processing. The brain structure studies use DTI to investigate dorsal and ventral white matter tract development. If the brain language system requires linguistic experience during early post-natal brain growth to become fully functional, then levels of syntactic development should correspond with the distribution and location of neurolinguistic processing in the brain as well as with the robustness of white matter tract development in the brain language network.