The human brain is made up of two halves called hemispheres. Each half of the brain is responsible for processing different kinds of information. Previous neuroimaging studies have shown that both the right and left hemispheres are involved when processing information given in American Sign Language (ASL). However, the study also showed that when processing spoken language, the left hemisphere was mostly involved.

Researchers would like to find out more about how the brain processes American Sign Language (ASL). This study is designed to determine if the right hemisphere is necessary for normal understanding of ASL.

The purpose of this protocol is to determine if the right hemisphere activation associated with perception of American Sign Language (ASL) in deaf subjects and in normal hearing individuals raised by deaf parents (who learned ASL before written English) is necessary for appropriate understanding of ASL.

Subject age between 18 and 65 years.

Adult hearing offsprings of deaf parents.

Congenitally deaf individuals.

Intact hearing volunteers.

No subjects with personal or family history of seizures or other neurological or demyelinating disorders.

No pregnant women tested after urine pregnancy test.

No subjects with severe coronary disease.

No subjects with metal in the cranium except mouth.

No subjects with intracardiac lines and implanted medication pumps.

No subjects with increased intracranial pressure as evaluated by clinical means.

No subjects with cardiac pacemakers.

No subjects with an intake of neuroleptics.