At times there are delays in oral language development. The age at which a child begins to speak is a behavioral marker of such delay. Children usually produce their first words between 10 and 15 months of age. A delay in speaking indicates atypical language development, and is one of the indicators of risk for reading disorder.31, 32 and 33Language milestones such as age at speaking can be evaluated in terms of the typical neural circuits that develop in the child.
A recent study of early and late talkers identified cortical and subcortical markers of children who spoke their first words at 1.2 years (early) versus those who spoke at 2.5 years (late). 34 In addition to better performance in language tests at 8 years of age, early talkers (also at 8 years of age) showed more activation in subcortical structures associated with the learning of rule-based systems (putamen and thalamus); these subcortical structures are at the basis of learning new linguistic skills. 35 and 36 Early milestones as simple as uttering two to three word sentences are strong indicators of language outcome, and the effects of age at speaking are associated with markers of brain development. Identifying early behaviors and understanding the consequences brain development provide a path for cognitive neuroscience to inform early intervention. Brain–behavior relationships help understand the typical interaction between psychological and biological processes, and the missing biological pieces in atypical development.