Revisiting brain rewiring and plasticity in children born without corpus callosum

• Published in: Developmental science Vol. 24; no. 6; pp. e13126 - n/a
• Main Authors: Siffredi, Vanessa, Preti, Maria G., Obertino, Silvia, Leventer, Richard J., Wood, Amanda G., McIlroy, Alissandra, Anderson, Vicki, Spencer‐Smith, Megan M., Van De Ville, Dimitri
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01.11.2021; John Wiley and Sons Inc
• Subjects: Adult; Agenesis of Corpus Callosum; Anterior commissure; Brain; brain plasticity; callosal dysgenesis; Cerebral hemispheres; Child; Children; Corpus Callosum; functional connectivity; Humans; Interhemispheric transfer; Neural networks; Neural Pathways; Neural plasticity; posterior commissure; Short Report; Short Reports; Substantia alba; tractography; White Matter; anterior commissure; posterior commissure; tractography; functional connectivity; callosal dysgenesis; brain plasticity
• ISSN: 1363-755X; 1467-7687
• DOI: 10.1111/desc.13126

The corpus callosum is the largest white matter pathway connecting homologous structures of the two cerebral hemispheres. Remarkably, children and adults with developmental absence of the corpus callosum (callosal dysgenesis, CD) show typical interhemispheric integration, which is classically impaired in adult split‐brain patients, for whom the corpus callosum is surgically severed. Tovar‐Moll and colleagues (2014) proposed alternative neural pathways involved in the preservation of interhemispheric transfer. In a sample of six adults with CD, they revealed two homotopic bundles crossing the midline via the anterior and posterior commissures and connecting parietal cortices, and the microstructural properties of these aberrant bundles were associated with functional connectivity of these regions. The aberrant bundles were specific to CD and not visualised in healthy brains. We extended this study in a developmental cohort of 20 children with CD and 29 typically developing controls (TDC). The two anomalous white‐matter bundles were visualised using tractography. Associations between structural properties of these bundles and their regional functional connectivity were explored. The proposed atypical bundles were observed in 30% of our CD cohort crossing via the anterior commissure, and in 30% crossing via the posterior commissure (also observed in 6.9% of TDC). However, the structural property measures of these bundles were not associated with parietal functional connectivity, bringing into question their role and implication for interhemispheric functional connectivity in CD. It is possible that very early disruption of embryological callosal development enhances neuroplasticity and facilitates the formation of these proposed alternative neural pathways, but further evidence is needed.