Functional and structural brain asymmetries in sign language processing.

Area of Science:

• Cognitive Neuroscience
• Linguistics
• Neurobiology

Background:

• Language is a defining human trait, not limited to speech.
• Sign languages are natural languages used by deaf communities, relying on visual-gestural modalities.
• Neuroimaging studies investigate the brain basis of sign language.

Purpose of the Study:

• To review the neural substrates of sign language processing.
• To examine functional and structural brain organization in sign language.
• To compare sign language processing with spoken/written language in the brain.

Main Methods:

• Review of neuroimaging research findings.
• Analysis of functional and structural brain organization.
• Comparison of left and right hemisphere involvement in sign language.

Main Results:

• Sign language processing is predominantly left-lateralized, similar to spoken language.
• The right hemisphere shows equipotentiality and supports unique signed modality constructions.
• A core language network in the left hemisphere is crucial for complex syntax, independent of modality.

Conclusions:

• The human brain exhibits remarkable plasticity in language processing across modalities.
• The left-hemisphere core language network is fundamental for complex syntax, suggesting evolutionary significance.
• Understanding sign language neural bases offers insights into the evolution of human language capacity.