title: Cortical thickness, cortico-amygdalar networks, and externalizing behaviors in healthy children.
abstract: BACKGROUND
  Fronto-amygdalar networks are implicated in childhood psychiatric disorders characterized by high rates of externalizing (aggressive, noncompliant, oppositional) behavior. Although externalizing behaviors are distributed continuously across clinical and nonclinical samples, little is known about how brain variations may confer risk for problematic behavior. Here, we studied cortical thickness, amygdala volume, and cortico-amygdalar network correlates of externalizing behavior in a large sample of healthy children.
  
  
  METHODS
  Two hundred ninety-seven healthy children (6-18 years; mean = 12 ± 3 years), with 517 magnetic resonance imaging scans, from the National Institutes of Health Magnetic Resonance Imaging Study of Normal Brain Development, were studied. Relationships between externalizing behaviors (measured with the Child Behavior Checklist) and cortical thickness, amygdala volume, and cortico-amygdalar structural networks were examined using first-order linear mixed-effects models, after controlling for age, sex, scanner, and total brain volume. Results significant at p ≤ .05, following multiple comparison correction, are reported.
  
  
  RESULTS
  Left orbitofrontal, right retrosplenial cingulate, and medial temporal cortex thickness were negatively correlated with externalizing behaviors. Although amygdala volume alone was not correlated with externalizing behaviors, an orbitofrontal cortex-amygdala network predicted rates of externalizing behavior. Children with lower levels of externalizing behaviors exhibited positive correlations between orbitofrontal cortex and amygdala structure, while these regions were not correlated in children with higher levels of externalizing behavior.
  
  
  CONCLUSIONS
  Our findings identify key cortical nodes in frontal, cingulate, and temporal cortex associated with externalizing behaviors in children; and indicate that orbitofrontal-amygdala network properties may influence externalizing behaviors, along a continuum and across healthy and clinical samples.
authors.affiliation: Department of Psychiatry, The Hospital for Sick Children, University of Toronto, Toronto.
authors.forename: Stephanie H
authors.initials: SH
authors.lastname: Ameis
authors.forename: Simon
authors.initials: S
authors.lastname: Ducharme
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Albaugh
authors.forename: James J
authors.initials: JJ
authors.lastname: Hudziak
authors.forename: Kelly N
authors.initials: KN
authors.lastname: Botteron
authors.forename: Claude
authors.initials: C
authors.lastname: Lepage
authors.forename: Lu
authors.initials: L
authors.lastname: Zhao
authors.forename: Budhachandra
authors.initials: B
authors.lastname: Khundrakpam
authors.forename: D Louis
authors.initials: DL
authors.lastname: Collins
authors.forename: Jason P
authors.initials: JP
authors.lastname: Lerch
authors.forename: Anne
authors.initials: A
authors.lastname: Wheeler
authors.forename: Russell
authors.initials: R
authors.lastname: Schachar
authors.forename: Alan C
authors.initials: AC
authors.lastname: Evans
authors.forename: Sherif
authors.initials: S
authors.lastname: Karama
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000679:Amygdala / Q000254:growth & development*; D002540:Cerebral Cortex / Q000033:anatomy & histology* / Q000254:growth & development*; D002648:Child; D002652:Child Behavior; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009434:Neural Pathways / Q000254:growth & development / Q000502:physiology; D011581:Psychological Tests
keywords: Amygdala; cortical thickness; externalizing behavior; healthy children and adolescents; network; structural magnetic resonance imaging