In deaf people, the brain region usually involved in processing speech sounds can adapt to process signals prompted by sign language, a study in this weeks Nature Communications shows. The study finds that sound deprivation causes changes to one side of this brain region, whereas sign language experience alters the other side. These results indicate that this brain region can adapt its function in response to different input signals while maintaining its ability to process language.
In congenitally deaf people, neural plasticity - reorganization of the brain in response to certain events - has been observed in the superior temporal cortex (STC), a region associated with auditory and speech sound processing. Velia Cardin and colleagues use functional magnetic resonance imaging (fMRI) to distinguish between the cortical changes in individuals who vary in hearing and sign language ability. They show that plastic effects in the left STC have a linguistic origin, and are shaped by sign language experience, whereas plasticity in the right STC is shaped by sensory deprivation.
These findings demonstrate that despite adaptive changes, the STC can preserve the nature of the computation it performs both at the sensory and cognitive level.