title: Direct and indirect effects of fetal irradiation on cortical gray and white matter volume in the macaque.
abstract: BACKGROUND
  Schizophrenia is associated with reductions in thalamic neuronal number and cortical gray matter volume. Exposure of nonhuman primates to x-irradiation in early gestation has previously been shown to decrease thalamic volume and neuronal number. Here we examine whether early gestational irradiation also results in cortical volume reduction.
  
  
  METHODS
  High-resolution, T1-weighted magnetic resonance scans were collected in adult monkeys 1) exposed to irradiation during the early gestational period (E33-E42) corresponding to thalamic neurogenesis, 2) irradiated in midgestation (E70-81) during neocortical neurogenesis, and 3) not exposed to irradiation. Cortical gray matter and white matter volumes were derived via manual segmentation; frontal and nonfrontal volumes were distinguished via sulcal landmarks.
  
  
  RESULTS
  Monkeys irradiated in early gestation exhibited a trend reduction in nonfrontal gray matter volume (17%) and significant reductions in white matter volume in frontal (26%) and nonfrontal (36%) lobes. Monkeys irradiated in midgestation had smaller gray (frontal: 28%; nonfrontal: 22%) and white matter (frontal: 29%; nonfrontal: 38%) volumes.
  
  
  CONCLUSIONS
  The cortical deficits observed in midgestationally irradiated monkeys are consistent with a reduction in cortical neuronal number. Cortical volume reductions following early gestational irradiation may be secondary to reduced thalamic neuronal number and therefore model the thalamocortical pathology of schizophrenia.
authors.affiliation: Department of Neurobiology, Yale University School of Medicine, PO Box 208001, New Haven, CT 06520-8001, USA. ldselemon@aol.com
authors.forename: Lynn D
authors.initials: LD
authors.lastname: Selemon
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.forename: Mary Beth
authors.initials: MB
authors.lastname: Nebel
authors.forename: John G
authors.initials: JG
authors.lastname: Csernansky
authors.forename: Patricia S
authors.initials: PS
authors.lastname: Goldman-Rakic
authors.forename: Pasko
authors.initials: P
authors.lastname: Rakic
mesh_terms: D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000473:pathology / Q000528:radiation effects*; D005260:Female; D008251:Macaca; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods; D008297:Male; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D011832:Radiation Injuries / Q000473:pathology*; D013788:Thalamus / Q000473:pathology / Q000528:radiation effects