Spatiotemporal Dynamics of Word Processing in the Bilingual Brain

学习第二种语言的能力几乎和掌握一种语言的能力一样了不起。然而，目前对人类大脑如何获取、组织和处理多种语言的理解非常有限。一个基本的问题是，多种语言是否在大脑的共同区域中表现出来。当单语者阅读时，单词会从大脑皮层的后端进入大脑皮层，然后向前传递。在十分之二秒内，这些单词被视觉编码，然后在接下来的十分之三秒内，它们在左颞叶和额叶的专门区域被编码为含义。在美国国家科学基金会（National Science Foundation）的支持下，加州大学圣迭戈分校（University of California at San Diego）的埃里克·哈尔格伦（Eric Halgren）博士和杰弗里·埃尔曼（Jeffrey Elman）博士及其同事将研究年轻人在用母语西班牙语或第二语言英语阅读单词时的单词编码，大多数人从上学开始就使用英语。皮层神经元利用电流处理信息，而电流又产生微小的磁场。这些将使用超导量子干涉装置阵列作为脑磁图进行检测，然后使用磁共振成像将其映射到特定的皮质区域。实验将确定英语和西班牙语单词的编码区域是否相同。具体来说，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使用相同的区域，但另外还访问右半球的相应区域。实验还将试图证实第二语言使用的大脑区域在其他方面参与高级视觉的说法，并探索第二语言是否以词语的感知表征为特征。实验将测试英语和西班牙语单词在处理流中的早期差异，以及这种差异是由于自上而下的策略控制还是快速分类。受试者对英语的了解程度和开始学习英语的时间各不相同，因此可以确定习得年龄、习得顺序和熟练程度的影响。这项研究将神经科学、认知科学、语言科学和成像科学结合起来，提供跨学科的培训，特别是对西班牙语和英语双语的学生，并将神经成像引入到以前主要是行为学研究的社会问题中。全球超过三分之二的人口使用多种语言。双语将美国的多种亚文化联系在一起，对于新移民的社会经济融合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.