Spatiotemporal Dynamics of Word Processing in the Bilingual Brain

学习第二门语言的能力几乎和懂一门语言的能力一样了不起。然而，目前对人脑如何获得、组织和处理多种语言的理解是非常有限的。一个根本的问题是，多种语言是否出现在共同的大脑区域。当只会说一种语言的人阅读时，单词在大脑皮质的后端进入，并向前移动。在十分之二秒内，这些单词被进行视觉编码，然后在接下来的十分之三秒内，它们被编码，以在左侧颞叶和额叶的特定区域表达意义。在国家科学基金会的支持下，加州大学圣地亚哥分校的埃里克·哈尔格伦博士和杰弗里·埃尔曼博士将与他们的同事一起，研究年轻人用母语西班牙语或第二语言英语阅读单词的单词编码，大多数人从上学开始就一直在使用英语。大脑皮层神经元使用电流处理信息，而电流又会产生微小的磁场。这些信号将使用超导量子干涉设备阵列作为脑磁图进行检测，然后使用磁共振成像映射到特定的皮质区域。实验将确定英语和西班牙语单词是否在相同的区域编码。具体地说，实验将测试一个模型，该模型假设第二种语言确实与第一种语言接触相同的区域，但另外还接触到右半球的相应区域。实验还将试图证实第二语言使用的是大脑中参与高级视觉的区域，并探索第二语言是否以对单词的知觉表征为特征。实验将测试英语和西班牙语单词在加工过程中的早期差异，以及这种差异是由于自上而下的策略控制还是快速分类所致。受试者对英语的了解程度和开始学习英语的时间会有所不同，因此可以确定习得年龄、习得顺序和熟练程度的影响。这项研究汇集了神经、认知、语言和成像科学，提供跨学科培训，特别是为掌握西班牙语和英语的双语学生提供培训，并将神经成像引入以前主要从行为上探讨的社会问题。全球超过三分之二的人口会说多种语言。双语将多种美国亚文化联系在一起，这对新移民的社会经济一体化以及美国商品和服务进入全球市场至关重要。然而，第二语言教育往往是无效的。更清楚地了解大脑如何组织多种语言将成为开发有效的第二语言教学方法的科学基础的一部分。

Almost as remarkable as the ability to know one language is the ability to learn a second. However, current understanding of how the human brain acquires, organizes, and processes multiple languages is highly limited. A fundamental issue is whether multiple languages are represented in common brain areas. When monolinguals read, words enter the cortex at its posterior tip, and work their way forward. Within two-tenths of a second, the words are encoded visually, and then in the next three-tenths of a second they are encoded for meaning in specialized areas of the left temporal and frontal lobes. With support from the National Science Foundation, Dr. Eric Halgren and Dr. Jeffrey Elman of the University of California at San Diego, with their colleagues, will study word encoding in young adults reading words in their native Spanish, or in their second language, English, which most have been using since they started school. Cortical neurons process information using electrical currents, which in turn produce minute magnetic fields. These will be detected using arrays of superconducting quantum interference devices as the magnetoencephalogram, and then mapped to particular cortical areas using magnetic resonance imaging. Experiments will determine if the English and Spanish words are encoded in the same areas. Specifically, experiments will test a model that hypothesizes that the second language does engage the same areas as the first, but in addition accesses the corresponding areas in the right hemisphere. Experiments will also attempt to confirm the suggestion that the second language uses brain areas which are otherwise engaged in high level vision, and explore if the second language is characterized by perceptual representations of words. Experiments will test how early in the processing stream English and Spanish words diverge, and whether this divergence is due to top-down strategic control or quick categorization. Subjects will vary in how well they know English and when they began learning it, so that the effects of age of acquisition, order of acquisition, and proficiency can be determined.This research brings together neural, cognitive, language and imaging sciences, providing interdisciplinary training, especially for bilingual Spanish-English students, and introducing neuroimaging to a societal problem previously approached mainly behaviorally. Over two-thirds of the global population is multi-lingual. Bilingualism binds together the multiple American subcultures, being essential for socioeconomic integration of recent immigrants, and for the access of American goods and services to a global marketplace. Yet, second language education is often ineffective. A clearer picture of how the brain organizes multiple languages will form part of the scientific basis for developing effective second language teaching methodologies.