Cross-hemispheric collaboration and segregation associated with task difficulty as revealed by structural and...

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neuroimaging

Background:

• Brain hemispheres can work together (collaboration) or independently (segregation).
• The specific brain regions and conditions influencing these interactions remain largely unknown.

Purpose of the Study:

• To investigate the brain regions and conditions associated with hemispheric collaboration and segregation.
• To understand how white matter integrity and functional connectivity support these interactions during cognitive tasks.

Main Methods:

• Used a split-field matching task with words and faces, manipulating task difficulty.
• Assessed white matter integrity using diffusion tensor imaging (DTI) fractional anisotropy (FA).
• Measured cross-hemispheric functional connectivity (CFC) using fMRI.

Main Results:

• A bilateral processing advantage (BPA) emerged as task difficulty increased.
• Specific white matter regions (anterior/posterior corpus callosum) correlated with BPA for different tasks.
• Cross-hemispheric functional connectivity increased in domain-general regions and decreased in domain-specific regions with rising difficulty.
• Functional connectivity mediated the relationship between white matter integrity and task performance.

Conclusions:

• Hemispheric collaboration is dynamically regulated by white matter structure and functional connectivity.
• These findings elucidate the neural mechanisms underlying interhemispheric communication in cognitive tasks.