Corpus callosum dysgenesis causes novel patterns of structural and functional brain connectivity

Diego Szczupak; Marina Kossmann Ferraz; Lucas Gemal; Patricia S Oliveira-Szejnfeld; Myriam Monteiro; Ivanei Bramati; Fernando R Vargas; IRC5 Consortium; Roberto Lent; Afonso C Silva; Fernanda Tovar-Moll

doi:10.1093/braincomms/fcab057

Corpus callosum dysgenesis causes novel patterns of structural and functional brain connectivity

Brain Commun. 2021 May 14;3(2):fcab057. doi: 10.1093/braincomms/fcab057. eCollection 2021.

Authors

Affiliations

¹ Department of Neurobiology, University of Pittsburgh Brain Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA.
² D'Or Institute of Research and Education (IDOR), Rio de Janeiro 22281-100, Brazil.
³ Genetics and Molecular Biology Department, Federal University of the State of Rio de Janeiro, Rio de Janeiro 20270-330, Brazil.
⁴ Birth Defects Epidemiology Laboratory, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro 21040-360, Brazil.
⁵ Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro 21941-902, Brazil.

Abstract

Developmental malformations (dysgenesis) of the corpus callosum lead to neurological conditions with a broad range of clinical presentations. Investigating the altered brain connectivity patterns is crucial to understanding both adaptive and maladaptive neuroplasticity in corpus callosum dysgenesis patients. Here, we acquired structural diffusion-weighted and resting-state functional MRI data from a cohort of 11 corpus callosum dysgenesis patients (five with agenesis and six with hypoplasia) and compared their structural and functional connectivity patterns to healthy subjects selected from the Human Connectome Project. We found that these patients have fewer structural inter- and intra-hemispheric brain connections relative to healthy controls. Interestingly, the patients with callosal agenesis have a scant number of inter-hemispheric connections but manage to maintain the full integrity of functional connectivity between the same cortical regions as the healthy subjects. On the other hand, the hypoplasic group presented abnormal structural and functional connectivity patterns relative to healthy controls while maintaining the same total amount of functional connections. These results demonstrate that acallosal patients can compensate for having fewer structural brain connections and present functional adaptation. However, hypoplasics present atypical structural connections to different brain regions, leading to entirely new and abnormal functional brain connectivity patterns.

Keywords: connectivity; connectome; corpus callosum; dMRI; fMRI.