Kavli Affiliate: Michael Miller
| Authors: Tyler Santander, Selin Bekir, Theresa Paul, Jessica M Simonson, Valerie M Wiemer, Henri Etel Skinner, Johanna L Hopf, Anna Rada, Friedrich G Woermann, Thilo Kalbhenn, Barry Giesbrecht, Christian G Bien, Olaf Sporns, Michael S Gazzaniga, Lukas J Volz and Michael B Miller
| Summary:
The dynamic integration of the lateralized and specialized capacities of the two cerebral hemispheres constitutes a hallmark feature of human brain function. This inter-hemispheric exchange of information is thought to critically depend upon the corpus callosum. Classical anatomical descriptions of callosal organization outline a topographic gradient from front to back, such that specific transcallosal fibers support distinct aspects of integrated brain function. Here we present a challenge to this conventional model. Using neuroimaging data obtained from a new cohort of adult 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 of posterior callosal fibers. Partial callosotomy patients with spared callosal fibers retained widespread patterns of inter-hemispheric functional connectivity and showed no signs of behavioral disconnection syndromes, even with only 1 cm of the splenium intact. Conversely, only complete corpus callosotomy patients demonstrated sweeping disruptions of 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.