1. Department of Neurology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York 10021, USA
2. Department of Neurology and Neuroscience, Cornell University Medical College, 1300 York Avenue, New York, New York 10021, USA

Correspondence to: Joy Hirsch^1,2 Correspondence and requests for materials should be addressed to J. Hirsch
(e-mail: Email: hirsch@vision.mskcc.org).

The ability to acquire and use several languages selectively is a unique and essential human capacity. Here we investigate the fundamental question of how multiple languages are represented in a human brain. We applied functional magnetic resonance imaging (fMRI) to determine the spatial relationship between native and second languages in the human cortex, and show that within the frontal-lobe language-sensitive regions (Broca's area)^{1, 2, 3}, second languages acquired in adulthood ('late' bilingual subjects) are spatially separated from native languages. However, when acquired during the early language acquisition stage of development ('early' bilingual subjects), native and second languages tend to be represented in common frontal cortical areas. In both late and early bilingual subjects, the temporal-lobe language-sensitive regions (Wernicke's area)^{1, 2, 3} also show effectively little or no separation of activity based on the age of language acquisition. This discovery of language-specific regions in Broca's area advances our understanding of the cortical representation that underlies multiple language functions.