Inner Hemispheric and Interhemispheric Connectivity Balance in the Human Brain

Area of Science:

• Neuroscience
• Network Science
• Human Connectomics

Background:

• Brain connectome structure significantly impacts neural information transfer speed and efficiency.
• Efficient network architecture is crucial for the brain, an organ with high energy demands.
• Previous research indicated conserved overall brain connectivity across species, attributed to a balance between interhemispheric and intrahemispheric connections.

Purpose of the Study:

• To investigate the connectivity trade-off between intrahemispheric and interhemispheric connections in the human brain.
• To explore the biological origins, heritability, and cognitive implications of this connectivity phenomenon.
• To analyze cohort-based network architecture within the Human Connectome Project dataset.

Main Methods:

• Utilized diffusion-based tractography and network analysis techniques.
• Analyzed data from a large cohort (970 subjects) within the Human Connectome Project.
• Examined the proportion of commissural fibers and their correlation with hemispheric efficiency.

Main Results:

• A negative correlation was found between the proportion of commissural fibers and hemispheric efficiency, confirming a connectivity trade-off.
• Key brain hubs, including the cingulate cortex, superior frontal, and medial occipital areas, significantly contributed to this phenomenon.
• High heritability of this network structure and a strong association with crystallized intelligence were observed.

Conclusions:

• The study confirms a connectivity conservation phenomenon underlying human brain network architecture.
• This conserved network structure may explain functional, behavioral, and cognitive variations among individuals.
• Understanding the interplay between hemispheric and commissural connectivity is vital for comprehending brain function and individual differences.