Structural and functional brain rewiring clarifies preserved interhemispheric transfer in humans born without the corpus callosum

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...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2014-05, Vol.111 (21), p.7843-7848
Main Authors: Tovar-Moll, Fernanda, Monteiro, Myriam, Andrade, Juliana, Bramati, Ivanei E., Vianna-Barbosa, Rodrigo, Marins, Theo, Rodrigues, Erika, Dantas, Natalia, Behrens, Timothy E. J., de Oliveira-Souza, Ricardo, Moll, Jorge, Lent, Roberto
Format: Article
Language:English
Subjects:
Adolescent
Adult
Agenesis of Corpus Callosum - physiopathology
Anatomy
Axons
Biological Sciences
Brain
Brain - physiopathology
Brain Mapping
Cerebral hemispheres
Child
Connectivity
Female
Forebrain
Humans
Image Processing, Computer-Assisted
Magnetic Resonance Imaging
Male
Medical imaging
Midbrain
Models, Neurological
Neural Pathways - physiology
Neuropsychological Tests
Neuropsychology
Object recognition
White matter
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Summary: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.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1400806111