ABSTRACT
Bilingualism represents a potential generator of cognitive changes and a modulator of brain plasticity. In this chapter, initially a description on how bilingualism has been associated with cognitive changes across the life span starting in infancy and continuing through childhood to adulthood and senescence, most studies have reported advantages in cognitive functions, including discrimination of a greater number of phonemes and faster development of other areas of cognition such as attention and memory. The sociocultural perspective of bilingualism is later analyzed. Per this perspective, higher psychological processes are mediated processes. In a bilingual person, it is crucial to understand the potential involvement of each language in private speech and hence in the regulation of psychological processes; current interpretations are discussed. The effect of bilingualism on neural development is reviewed in the following section. It is concluded that both structural and functional differences have been reported in the brain of bilinguals. Functional studies, on the other hand, have shown that managing more than one language, particularly from early childhood, has an impact on patterns of brain activation. Language processing in bilinguals is more complex than in monolinguals, and recruits larger brain areas. Finally, aphasia and dementia characteristics in bilinguals are examined.
