Hemispheric lateralization of language processing: insights from network-based symptom mapping and patient subgroups

Area of Science:

• Neuroscience
• Cognitive Science
• Computational Neuroscience

Background:

• Hemispheric laterality of language processing is debated, with studies reporting left-lateralized or bilateral patterns.
• A neurocomputational model suggests initial symmetry but imbalanced capacity explains discrepancies and recovery disparities.

Purpose of the Study:

• To investigate the proposed neurocomputational model of language processing.
• To analyze language subnetwork lateralization patterns in patients and healthy individuals.
• To examine lateralization in subgroups with different hemispheric injuries.

Main Methods:

• Utilized a whole-brain network-based lesion-symptom mapping method.
• Analyzed lateralization patterns of language and non-language subnetworks in 99 patients.
• Quantitatively measured the lateralization index and examined subgroups with unilateral brain damage.

Main Results:

• All language processing subnetworks demonstrated left-lateralization.
• Non-language processing subnetworks exhibited varied lateralization patterns.
• Hemisphere-specific injury subgroups showed distinct language recovery outcomes.

Conclusions:

• Findings provide robust support for the neurocomputational model of language processing.
• The model successfully explains discrepancies in previous laterality studies and recovery disparities.