Cortical Connections Conference 2019

A characterization of the normal and abnormal inter-hemispheric connections with diffusion weighted MRI and histology in mice, monkeys and humans with normal and abnormal corpus callosum morphology. To characterize the Balb/c strain long distance plasticity and compare to the human dysgenesis of the Corpus Callosum (dCC), we employed MRI to evaluate the white matter plasticity. We found that Balb/c strain presents abnormal bundles similar to the human dCC patients. More than that, we found that the brain anatomy of Balb/c strain is different from C57bl6 even in animals with apparently normal CC. Using a histological tracer technique, aav9, we were able to confirm these bundles and we found that the strain C57bl6 also has these supposed abnormal fibers. We also used a connectomic approach and discovered that the Balb/c strain variability is not only related to the size of the CC, but also to the global connectivity with the frontal pole as the most affected cortical region. Then we focused on the human patients, and with the same connectomic approach, we evaluated the whole brain connectivity and found that, in a similar way to the mice, the humans with dCC present many intra-hemispheric alterations and a shift from the inter-hemispheric connectivity to intra-hemispheric. We also have found that there are marmoset monkeys with a hypoplasic corpus callosum and using diffusion weighted MRI and fMRI, we are characterizing how the brain networks are altered in face of the altered white matter structure.

Acknowledgements: NIH intra mural funding, Cappes and CNPq