Full inter-hemispheric integration sustained by a fraction of posterior callosal fibers

Santander, T.; Bekir, S.; Paul, T.; Simonson, J. M.; Wiemer, V. M.; Skinner, H. E.; Hopf, J. L.; Rada, A.; Woermann, F. G.; Kalbhenn, T.; Giesbrecht, B.; Bien, C. G.; Sporns, O.; Gazzaniga, M. S.; Volz, L. J.; Miller, M. B.

doi:10.1101/2025.02.14.638327

bioRxiv · 10.1101/2025.02.14.638327

Full inter-hemispheric integration sustained by a fraction of posterior callosal fibers

Santander, T.·Bekir, S.·Paul, T.·Simonson, J. M.·Wiemer, V. M.·Skinner, H. E.·Hopf, J. L.·Rada, A.·Woermann, F. G.·Kalbhenn, T.·Giesbrecht, B.·Bien, C. G.·Sporns, O.·Gazzaniga, M. S.·Volz, L. J.·Miller, M. B.

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Abstract

The dynamic integration of the lateralized and specialized capacities of the cerebral hemispheres constitutes a hallmark feature of human brain function. This inter-hemispheric exchange of information critically depends upon the corpus callosum. Classical descriptions of callosal organization outline a topographic gradient, such that specific fibers integrate distinct aspects of brain function. Here we present a challenge to this conventional model. Using neuroimaging data obtained from a new cohort of adult corpus callosotomy patients, we leverage modern network neuroscience techniques to show--for the first time--that full inter-hemispheric integration can be achieved via a small proportion ([~]1 cm) of intact posterior callosal fibers. Only complete callosotomy patients demonstrated the expected dissolution of typical inter-hemispheric network architectures, aligning with disconnection syndromes long-thought to reflect diminished information propagation and communication across the brain. These findings motivate a novel mechanistic understanding of synchronized inter-hemispheric neural activity for large-scale human brain function and behavior.

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Santander, T., Bekir, S., Paul, T., Simonson, J. M., Wiemer, V. M., Skinner, H. E., Hopf, J. L., Rada, A., Woermann, F. G., Kalbhenn, T., Giesbrecht, B., Bien, C. G., Sporns, O., Gazzaniga, M. S., Volz, L. J., Miller, M. B.. 2025-02-16. Full inter-hemispheric integration sustained by a fraction of posterior callosal fibers. https://doi.org/10.1101/2025.02.14.638327

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