Neurodevelopmental Aspects of Language

Neurodevelopmental Aspects of Language

Any description of the relationship between the brain and language would be incomplete without considering some neurodevelopmental aspects of language. As a comprehensive dis-cussion of this subject is beyond the scope of this section, the fo-cus here is on presenting central theoretical issues. Some of these issues help shed light on the ways in which the brain is organized for language in children. For discussions of language disorders in children, the reader is referred to Yule and Rutter (1987).

Language Acquisition

One central issue addresses the notion of the innateness of lan-guage. Interest in this concept was stimulated by the pioneeringwork of Chomsky (1988), who espoused the view of an in-nate human capacity to know the universal rules of grammar. Chomsky drew attention to the fact that despite differences in the languages of the world, all human languages have the same universal features. Consequently, learning a language is some-thing that “happens” to a child (Goldberg, 1989).

The fact that there are universal regularities in the acquisi-tion of language supports the notion of an innate capacity. Thus, according to Lenneberg (1967, 1969), an infant’s language capa-bilities are linked with physical maturation and there is therefore a correlation between language development and motor develop-ment. Thus, by about 15 months of age, when the motor milestone of self-propulsive gait is attained, an infant has a vocabulary of three to 50 words; by 18 to 24 months, when a child begins to run (with falls), many two-word utterances are observed (Lenneberg, 1969; Brown, 1973). By about 3 to 4 years of age, a child ac-quires the capability for many fully grammatical utterances (Stromswold, 1995).

In the literature dealing with the issue of language acquisi-tion, much consideration has been given to the relative influences of genetic and environmental factors. Individual differences in performance raise questions about the relative contributions of these factors in language acquisition. On the one hand, it has been thought that if language is indeed an innate capacity with associated neural mechanisms, then language functions and mal-functions must also have a genetic basis.

Evidence for a genetic basis has come from many sources, especially from research in the area of developmental language disorders. Based on a review of relevant studies, Stromswold (1995) reported the finding of a higher incidence of language impairment in families of children with developmental disorders than in families of children without such impairment.

With respect to the view of language as an innate capacity, it is generally believed that language can be acquired without ex-plicit instruction. For example, Stromswold (1995) reported that even children who are unable to speak and therefore cannot be corrected are capable of acquiring normal receptive language. In addition to the evidence that supports genetic contributions to language functions and dysfunctions, there is indirect support for the role of environmental exposure from studies of individu-als raised in severely deprived environments. Studies of “wild” children raised in conditions of extreme linguistic, social and emotional deprivation essentially suggested an innate hypothesis for language acquisition but also suggested that the environment can have some modifying influences.