title: Structural and functional brain rewiring clarifies preserved interhemispheric transfer in humans born without the corpus callosum.
abstract: Why do humans born without the corpus callosum, the major interhemispheric commissure, lack the disconnection syndrome classically described in callosotomized patients? This paradox was discovered by Nobel laureate Roger Sperry in 1968, and has remained unsolved since then. To tackle the hypothesis that alternative neural pathways could explain this puzzle, we investigated patients with callosal dysgenesis using structural and functional neuroimaging, as well as neuropsychological assessments. We identified two anomalous white-matter tracts by deterministic and probabilistic tractography, and provide supporting resting-state functional neuroimaging and neuropsychological evidence for their functional role in preserved interhemispheric transfer of complex tactile information, such as object recognition. These compensatory pathways connect the homotopic posterior parietal cortical areas (Brodmann areas 39 and surroundings) via the posterior and anterior commissures. We propose that anomalous brain circuitry of callosal dysgenesis is determined by long-distance plasticity, a set of hardware changes occurring in the developing brain after pathological interference. So far unknown, these pathological changes somehow divert growing axons away from the dorsal midline, creating alternative tracts through the ventral forebrain and the dorsal midbrain midline, with partial compensatory effects to the interhemispheric transfer of cortical function.
authors.affiliation: D'Or Institute for Research and Education (IDOR), 22281-032, Rio de Janeiro, Brazil;Institute of Biomedical Sciences (ICB) andNational Institute for Translational Neuroscience (INNT), Ministry of Science and Technology, Brazil;National Center of Structural Biology and Bioimaging (CENABIO), Federal University of Rio de Janeiro, 21941-902, Rio de Janeiro, Brazil; fernanda.tovarmoll@idor.org rlent@icb.ufrj.br.
authors.forename: Fernanda
authors.initials: F
authors.lastname: Tovar-Moll
authors.affiliation: D'Or Institute for Research and Education (IDOR), 22281-032, Rio de Janeiro, Brazil;Institute of Biomedical Sciences (ICB) and.
authors.forename: Myriam
authors.initials: M
authors.lastname: Monteiro
authors.affiliation: D'Or Institute for Research and Education (IDOR), 22281-032, Rio de Janeiro, Brazil;Institute of Biomedical Sciences (ICB) and.
authors.forename: Juliana
authors.initials: J
authors.lastname: Andrade
authors.affiliation: D'Or Institute for Research and Education (IDOR), 22281-032, Rio de Janeiro, Brazil;Institute of Biomedical Sciences (ICB) and.
authors.forename: Ivanei E
authors.initials: IE
authors.lastname: Bramati
authors.affiliation: D'Or Institute for Research and Education (IDOR), 22281-032, Rio de Janeiro, Brazil;Institute of Biomedical Sciences (ICB) and.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Vianna-Barbosa
authors.affiliation: D'Or Institute for Research and Education (IDOR), 22281-032, Rio de Janeiro, Brazil;Institute of Biomedical Sciences (ICB) and.
authors.forename: Theo
authors.initials: T
authors.lastname: Marins
authors.affiliation: D'Or Institute for Research and Education (IDOR), 22281-032, Rio de Janeiro, Brazil;Augusto Motta University (Unisuam), 21041-020, Rio de Janeiro, Brazil; and.
authors.forename: Erika
authors.initials: E
authors.lastname: Rodrigues
authors.affiliation: D'Or Institute for Research and Education (IDOR), 22281-032, Rio de Janeiro, Brazil;Institute of Biomedical Sciences (ICB) and.
authors.forename: Natalia
authors.initials: N
authors.lastname: Dantas
authors.affiliation: Centre for Functional Magnetic Resonance Imaging of the Brain, Oxford University, Oxford OX3 9DU, United Kingdom.
authors.forename: Timothy E J
authors.initials: TE
authors.lastname: Behrens
authors.affiliation: D'Or Institute for Research and Education (IDOR), 22281-032, Rio de Janeiro, Brazil;
authors.forename: Ricardo
authors.initials: R
authors.lastname: de Oliveira-Souza
authors.affiliation: D'Or Institute for Research and Education (IDOR), 22281-032, Rio de Janeiro, Brazil;National Institute for Translational Neuroscience (INNT), Ministry of Science and Technology, Brazil;
authors.forename: Jorge
authors.initials: J
authors.lastname: Moll
authors.affiliation: D'Or Institute for Research and Education (IDOR), 22281-032, Rio de Janeiro, Brazil;Institute of Biomedical Sciences (ICB) andNational Institute for Translational Neuroscience (INNT), Ministry of Science and Technology, Brazil; fernanda.tovarmoll@idor.org rlent@icb.ufrj.br.
authors.forename: Roberto
authors.initials: R
authors.lastname: Lent
mesh_terms: D000293:Adolescent; D000328:Adult; D061085:Agenesis of Corpus Callosum / Q000503:physiopathology*; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D002648:Child; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008959:Models, Neurological; D009434:Neural Pathways / Q000502:physiology*; D009483:Neuropsychological Tests
keywords: callosal agenesis; callosal plasticity; human connectome