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Hemispheric specialization for English and ASL: left invariance-right variability
D Bavelier1, D Corina, P Jezzard
1Georgetown Institute for Cognitive and Computational Sciences, Washington, DC 20007, USA.
Neuroreport
|June 19, 1998
Summary
The left hemisphere processes both spoken English and American Sign Language (ASL), indicating a modality-independent language bias. However, ASL also engages the right hemisphere, suggesting language-specific processing needs.
Area of Science:
- Neuroscience
- Linguistics
- Cognitive Science
Background:
- The brain's language processing centers are typically localized in the left hemisphere.
- It is unclear if this left-hemisphere dominance applies to sign languages, which are visually perceived.
Purpose of the Study:
- To investigate the cerebral organization for sentence processing in spoken English and American Sign Language (ASL).
- To determine if language modality influences brain lateralization for language.
Main Methods:
- Functional magnetic resonance imaging (fMRI) was employed.
- Brain activity was compared between native English speakers processing English and native ASL signers processing ASL.
Main Results:
- Both English and ASL recruited classical language areas in the left hemisphere.
- American Sign Language (ASL) showed significant recruitment of right hemisphere structures, unlike English.
- This right-hemisphere engagement in ASL was observed in both deaf and hearing native signers.
Conclusions:
- The left hemisphere exhibits a bias for processing natural languages regardless of sensory modality.
- The specific processing demands of a language, such as ASL's spatial nature, contribute to its neural organization.
- Language modality and processing requirements interact to shape the brain's language networks.