Neural systems underlying British Sign Language and audio-visual English processing in native users.

Area of Science:

• Neuroscience
• Linguistics
• Cognitive Science

Background:

• Understanding language evolution requires examining neural systems for processing.
• Distinguishing between sensory processing and symbolic representation is key.
• Investigating how auditory experience versus language exposure shapes brain systems is crucial.

Purpose of the Study:

• To explore modality-independent and modality-dependent language localization patterns.
• To investigate the neural basis of British Sign Language (BSL) perception.
• To compare brain activation in deaf and hearing native BSL signers.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to measure brain activation.
• Participants included hearing and congenitally deaf native BSL users, and hearing non-signers.
• Tasks involved BSL sentence acceptability and audio-visual English sentence processing.

Main Results:

• Modality-independent regions (inferior prefrontal, superior temporal) were activated by both BSL and spoken English.
• Spoken English showed greater activation in auditory cortices; BSL showed enhanced activation in occipito-temporal regions (V5).
• Deaf native signers showed greater left superior temporal gyrus activation for BSL than hearing native signers.

Conclusions:

• Language processing exhibits both modality-independent and modality-dependent localization.
• Left temporal auditory regions may be privileged for spoken language but can be recruited for visual processing in the absence of auditory input.
• Hearing status influences neural recruitment for sign language processing.