Quantifying agreement between anatomical and functional interhemispheric correspondences in the resting brain

Area of Science:

• Neuroscience
• Brain Imaging
• Computational Anatomy

Background:

• The human brain exhibits broad symmetry between its cerebral hemispheres.
• Accurate correspondence between homologous brain regions is challenging due to variable cortical folding.

Purpose of the Study:

• To develop a novel method for establishing precise anatomical and functional correspondence between cerebral hemispheres.
• To quantify hemispheric functional symmetry using resting-state functional Magnetic Resonance Imaging (fMRI).

Main Methods:

• A new landmark-based method using the unfolded cortical surface and gyral/sulcal patterns was developed.
• This method was compared against reversing standard volume coordinates for accuracy.
• Resting-state fMRI data were analyzed to map functional symmetry across the entire cortex.

Main Results:

• The landmark method demonstrated superior accuracy compared to standard coordinate-based approaches.
• Nearly half of the cortex showed maximal functional correlation within 1 cm on the cortical surface.
• Precise symmetric relationships were identified as the norm, not the exception.

Conclusions:

• The developed landmark method enables accurate hemispheric correspondence, overcoming limitations of variable cortical folding.
• Widespread, fine-grained functional symmetry exists in resting brain activity, particularly in motor, occipital, and inferior frontal cortices.
• This provides a more precise understanding of brain organization and function.