title: Altered white matter connectivity and network organization in polymicrogyria revealed by individual gyral topology-based analysis.
abstract: Polymicrogyria (PMG) is a cortical malformation characterized by multiple small gyri and altered cortical lamination, which may be associated with disrupted white matter connectivity. However, little is known about the topological patterns of white matter networks in PMG. We examined structural connectivity and network topology using individual primary gyral pattern-based nodes in PMG patients, overcoming the limitations of an atlas-based approach. Structural networks were constructed from structural and diffusion magnetic resonance images in 25 typically developing and 14 PMG subjects. The connectivity analysis for different fiber groups divided based on gyral topology revealed severely reduced connectivity between neighboring primary gyri (short U-fibers) in PMG, which was highly correlated with the regional involvement and extent of abnormal gyral folding. The patients also showed significantly reduced connectivity between distant gyri (long association fibers) and between the two cortical hemispheres. In relation to these results, gyral node-based graph theoretical analysis revealed significantly altered topological organization of the network (lower clustering and higher modularity) and disrupted network hub architecture in cortical association areas involved in cognitive and language functions in PMG patients. Furthermore, the network segregation in PMG patients decreased with the extent of PMG and the degree of language impairment. Our approach provides the first detailed findings and interpretations on altered cortical network topology in PMG related to abnormal cortical structure and brain function, and shows the potential for an individualized method to characterize network properties and alterations in connections that are associated with malformations of cortical development.
authors: Division of Newborn Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA; Fetal Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA. Electronic address: Kiho.Im@childrens.harvard.edu.
authors: Kiho
authors: K
authors: Im
authors: Deptartment of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.
authors: Michael J
authors: MJ
authors: Paldino
authors: Deptartment of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.
authors: Annapurna
authors: A
authors: Poduri
authors: Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405, USA.
authors: Olaf
authors: O
authors: Sporns
authors: Division of Newborn Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA; Fetal Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA; Deptartment of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.
authors: P Ellen
authors: PE
authors: Grant
mesh_terms: D000293:Adolescent; D002540:Cerebral Cortex / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D063132:Connectome / Q000379:methods*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D054220:Malformations of Cortical Development / Q000473:pathology*; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D009415:Nerve Net / Q000473:pathology*; D055815:Young Adult
keywords: Cortical malformation; Diffusion tensor imaging; Gyral pattern; Polymicrogyria; Structural connectivity network