Early language experience is thought to be essential to develop a high level of linguistic proficiency in adulthood. Impoverished language input during childhood has been found to lead to functional changes in the brain. In this study, we explored if delayed exposure to a first language modulates the neuroanatomical development of the brain. To do so, voxel-based morphometry (VBM) was carried out in a group of congenitally deaf individuals varying in the age of first exposure to American Sign Language (ASL). To explore a secondary question about the effect of auditory deprivation on structural brain development, a second VBM analysis compared deaf individuals to matched hearing controls. The results show that delayed exposure to sign language is associated with a decrease in grey-matter concentration in the visual cortex close to an area found to show functional reorganization related to delayed exposure to language, while auditory deprivation is associated with a decrease in white matter in the right primary auditory cortex. These findings suggest that a lack of early language experience alters the anatomical organization of the brain.

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