Language processing during natural sleep in a 6-year-old boy, as assessed with functional MR imaging.

Functional MR imaging for language lateralization was performed in a 6-year-old child before neurosurgical intervention. A passive story-listening task was used; this revealed a bilateral language network. The task was repeated during the same session when the child had fallen asleep and surprisingly yielded strong activation in similar language areas. Our findings suggest that language processing does occur during natural sleep, even in young children. This potentially allows for an assessment of language functions, even in sleeping children.