Structural neuroplastic responses preserve functional connectivity and neurobehavioural outcomes in children born without corpus callosum

Abstract

AbstractBackgroundThe corpus callosum is the largest white matter pathway in the brain connecting the left and the right hemispheres. Developmental absence of the corpus callosum is a model disease for exploring disrupted connectivity and in turn understanding plasticity of the human brain, with atypically developing structure and function resulting in a highly heterogeneous clinical and cognitive profile. A proposed candidate for neuroplastic response in the context of this brain malformation is strengthening of intra-hemispheric pathways.MethodsTo test this hypothesis, we assessed structural and functional connectivity at the whole-brain and regional level in a uniquely large cohort of children with agenesis of the corpus callosum (AgCC, n = 20) compared with typically developing controls (TDC, n = 29), and then examined associations with neurobehavioural outcomes using a multivariate data-driven approach.ResultsFor structural connectivity, children with AgCC showed a significant increase in intrahemispheric connectivity in addition to a significant decrease in inter-hemispheric connectivity compared with TDC. In contrast, for functional connectivity, children with AgCC and TDC showed a similar pattern of intra-hemispheric and inter-hemispheric connectivity. In AgCC, structural strengthening of the intra-hemispheric pathway was uniquely associated with verbal learning and memory, attention and executive measures.ConclusionsWe observed structural strengthening of intra-hemispheric pathways in children born without corpus callosum, which seems to allow for functional connectivity comparable to a typically developing brain, and were relevant to explain neurobehavioural outcomes in this population. This neuroplasticity might be relevant to other disorders of axonal guidance, and developmental disorders in which corpus callosum alteration is observed.