In this chapter, we explore neural representations and language processing in the bilingual brain. We begin by discussing key language areas and lateralization in bilinguals and look at some of the primary functions of the hemispheres, noting that, in fact, many brain functions – including bilingual language processing – are distributed across both hemispheres. We then consider the function of the four lobes of the brain and identify important regions for language, including Broca’s and Wernicke’s areas, which have been found to support language production and comprehension, respectively. The chapter then addresses how early or late exposure to a second language (L2) affects the cortical representation of the two languages. We then turn to specific processes of language use, namely how bilinguals comprehend and produce language. Overall, we have seen that the neural representations and processing of two languages are far from being fully understood. Nonetheless, we are gaining a clearer picture of the dynamic nature of two languages in one brain and the many individual differences that can affect this, such as age of acquisition (AoA) and proficiency.

Chapter 15 looks at the brain’s anatomy in terms of the areas important for language. It shows that, typically, the left hemisphere is widely responsible for language competence and performance. Readers learn about common methods and technologies used to study the brain, including lesion studies and autopsies, dichotic listening and split-brain studies, neuroimaging, and studies measuring the brain’s electric and magnetic fields. These methods have provided an incredible advantage to better understanding brain and language. This is especially apparent regarding language impairments that result from acquired brain damage or injury (either instantaneous or progressive). Some impairments discussed in the chapter include forms of aphasia: non-fluent, fluent, and primary progressive along with language disturbances primarily related to reading (e.g., alexia) and writing (e.g., agraphia) abilities. Finally, the chapter discusses how neurolinguistics informs what we know about the mental lexicon—words, their sounds, and meanings—along with morphology and syntax. Research using state-of-the-art technologies has informed us about which language functions rely on which brain structures.