What's right about the neural organization of sign language? A perspective on recent neuroimaging results.

Evidence from sign language Sign language provides a unique perspective on these questions. Because signed and spoken languages share linguistic representational structure, but differ radically with respect to their surface sensory and motor forms, a comparison of the neurobiology of the two systems can lead to a better understanding of the brain organization for linguistic processing with modality-specific contributions factored out. There is now a relatively large body of evidence relevant to this issue. Neuropsychological studies have uniformly confirmed a dominant role for the left hemisphere in sign language understanding and production in deaf signers1,2. A number of case studies2,3 and one relatively largescale group study4 of unilateral brain lesioned signers have shown that left hemisphere damage often produces aphasia for sign language whereas right hemisphere damage does not. The differential effects of left versus right brain damage in the deaf signing population can be seen from Fig. 1. This effect holds even when one controls for variables such as age of onset of deafness, age of exposure to sign H i c k o k e t a l . – N e u r a l o r g a n i z a t i o n o f s i g n l a n g u a g e Update Comment