title: Regional brain activity during early visual perception in unaffected siblings of schizophrenia patients.
abstract: BACKGROUND
  Visual masking paradigms assess the early part of visual information processing, which may reflect vulnerability measures for schizophrenia. We examined the neural substrates of visual backward performance in unaffected sibling of schizophrenia patients using functional magnetic resonance imaging (fMRI).
  
  
  METHODS
  Twenty-one unaffected siblings of schizophrenia patients and 19 healthy controls performed a backward masking task and three functional localizer tasks to identify three visual processing regions of interest (ROI): lateral occipital complex (LO), the motion-sensitive area, and retinotopic areas. In the masking task, we systematically manipulated stimulus onset asynchronies (SOAs). We analyzed fMRI data in two complementary ways: 1) an ROI approach for three visual areas, and 2) a whole-brain analysis.
  
  
  RESULTS
  The groups did not differ in behavioral performance. For ROI analysis, both groups increased activation as SOAs increased in LO. Groups did not differ in activation levels of the three ROIs. For whole-brain analysis, controls increased activation as a function of SOAs, compared with siblings in several regions (i.e., anterior cingulate cortex, posterior cingulate cortex, inferior prefrontal cortex, inferior parietal lobule).
  
  
  CONCLUSIONS
  The study found: 1) area LO showed sensitivity to the masking effect in both groups; 2) siblings did not differ from controls in activation of LO; and 3) groups differed significantly in several brain regions outside visual processing areas that have been related to attentional or re-entrant processes. These findings suggest that LO dysfunction may be a disease indicator rather than a risk indicator for schizophrenia.
authors.affiliation: Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, California 90095-6968, USA. jungheelee@ucla.edu
authors.forename: Junghee
authors.initials: J
authors.lastname: Lee
authors.forename: Mark S
authors.initials: MS
authors.lastname: Cohen
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Engel
authors.forename: David
authors.initials: D
authors.lastname: Glahn
authors.forename: Keith H
authors.initials: KH
authors.lastname: Nuechterlein
authors.forename: Jonathan K
authors.initials: JK
authors.lastname: Wynn
authors.forename: Michael F
authors.initials: MF
authors.lastname: Green
mesh_terms: D000328:Adult; D001921:Brain / Q000098:blood supply / Q000503:physiopathology*; D001931:Brain Mapping; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010470:Perceptual Masking / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D012559:Schizophrenia / Q000473:pathology* / Q000503:physiopathology; D012565:Schizophrenic Psychology; D035781:Siblings; D013997:Time Factors; D014796:Visual Perception / Q000502:physiology*
chemical_list: D010100:Oxygen