Complementary hemispheric lateralization of language and social processing in the human brain

Humans have a unique ability to use language for social communication. The neural architecture for language comprehension and production may have emerged in the brain areas that were originally involved in social cognition. Here we directly tested the fundamental link between language and social processing using functional MRI data from over 1000 human subjects. Cortical activations in language and social tasks showed a striking similarity with a complementary hemispheric lateralization; within core language areas, the activations were left-lateralized in the language task and right-lateralized in the social task. Outside these areas, the activations were left-lateralized in both tasks, perhaps indicating multimodal integration of social and communicative information. Our findings could have important implications in understanding neurocognitive mechanisms of social disorders such as autism.