Language development as a marker of normal brain development

Depending on how broadly or narrowly defined, language can include multiple processes which go well beyond speech production and comprehension. Though typical language development is a stepping stone process based on its component parts, such as phonology, morphology, syntax, and pragmatics, it quickly branches into a vehicle for broad communication, including gestures, social and affective orientation toward others, and the facilitation of our learning and thinking skills. Considering its involvement in so much of what we do, language has been proven to be an extremely complex and diffusely distributed function in the human brain. Considerable research shows that individual language process development proceeds in a very predictable manner and parallels specific areas of brain development. Research appears to support a critical period hypothesis during which the brain is maximally sensitive to specific types of language stimulation required for acquisition of skills associated with the next developmental phase. Thus, it seems clear that both genetics and environmental factors are important. Delays in the development of language skills and acquired deviations from normal language functioning can often be diagnostic of a pathological process. Given the great specificity in knowledge regarding the many neuroanatomical structures involved in language, language symptoms can be reasonably well localized in the brain. When language development deviates from the normal timeline, clinical interventions are often essential. Most evidence suggests that earlier intervention is more efficient. There are many creative and evidenced based treatments for language delays; however, depending on the severity and duration of the delay, the amount of treatment needed and the prognosis can vary widely. In cases where a delay is extreme there are often other noted cognitive and social deficits. Some speculate that delayed language could even plausibly limit the development of many other cognitive skills. This chapter discusses the more current broad conceptualization of language development and many of the evidencebased treatments. These include behavioral interventions such as Discrete Trial Training, as well as other methods: parent mediated, narrative mediated, social communication interventions, and sensory based interventions.