Sign language: How does the brain process it?

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sign language
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Our brain has three primary parts: the cerebrum, cerebellum, and brainstem. The cerebrum fills most of the skull and it consists of two sections: left and right hemispheres. Each of them has four parts, known as the lobes and they are assigned a specific task to perform. The Broca’s area located in the left frontal lobe is responsible for speech production and articulation, and the Wernicke’s area, in the left temporal lobe, is associated with language development and comprehension.

Since the development of sign languages for deaf and mute persons in the ‘60s, scientists have tried to understand the procedure by which our brain process sign language. In a recent study, researchers from Max Planck Institute for Human Cognitive and Brain Sciences tried to find the answer and their work was published in the Human Brain Mapping journal.

Where did the researchers look for sign language processing?

The team pooled data from global studies on sign language processing experiments and then they compared their study with thousands of brain scans across the globe for the betterment of their result. They found that the Brocas’s area plays an important role to process the sign language as well, besides spoken language processing. The researchers also found that the right frontal brain part is also associated with sign language processing. According to the group leader of the study, Emiliano Zaccarella, “For the first time, we were able to statistically and robustly identify the brain regions that were involved in sign language processing across all studies.”

What do we learn new from the study?

This study confirms and establishes the Broca’s area to be the central node of the brain for language processing, irrespective of its form, be it a written, spoken, or sign one. The movements of hands, face, and body are perceived similarly by deaf and normal people. For deaf people, the language network in the whole left hemisphere of the brain additionally gets activated alongside the Broca’s area.

The team is now conducting a detailed study to look into the Broca’s area to find whether different parts of it contribute to providing meaning or the grammar of sign language in deaf people, like for normal people.

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