Developmental disorders of speech and language: From genes to brain structure and function

Functional and structural brain imaging studies of developmental disorders provide insights into their neural correlates and have potential to bridge the gap between genotype and phenotype. We have used such techniques to investigate the neural correlates of two developmental disorders of speech and language, in which a genetic etiology is either known or strongly suspected. The first disorder is one shared by the affected members of the KE family who have a mutation in the FOXP2 gene. The brain structural and functional correlates of this disorder help clarify the nature of the behavioral impairment. They confirm that a deficit in auditory-motor learning of articulation patterns is core to the behavioral phenotype. In the second disorder, developmental stuttering, brain imaging data reveal functional abnormalities consistent with theories that it is caused by a basal ganglia deficit and structural differences consistent with an impairment in auditory-motor integration necessary for fluent speech. The common finding of basal ganglia abnormality in two developmental disorders of speech and language is discussed.