title: The effect of working memory performance on functional MRI in schizophrenia.
abstract: BACKGROUND
  Studies of prefrontal cortical (PFC) function in schizophrenia have been inconsistent, with studies showing both increased and decreased PFC activation compared to healthy controls. Discrepant findings may be due to task performance effects or demographic differences between samples. We report functional magnetic resonance imaging (fMRI) data comparing subjects with schizophrenia and healthy controls performing a 2-back working memory (WM) task, addressing the effects of task performance.
  
  
  METHODS
  Twenty-two controls and 14 patients with DSM-IV schizophrenia, scanned on a Siemens 1.5 T scanner, performed a visual letter 2-back task and control task (CPT-X) during fMRI. Data were analyzed using Statistical Parametric Mapping (SPM)-99.
  
  
  RESULTS
  After statistical adjustment for performance differences, persons with schizophrenia showed significantly greater activation than controls in the right medial frontal gyrus and left inferior parietal lobule/medial temporal gyrus region (BA 39/40), and a trend toward greater activation in the left ventrolateral PFC. This pattern was also observed in demographically matched subgroups of participants.
  
  
  CONCLUSIONS
  Data are consistent with findings reported in recent studies showing increased PFC and parietal activation in schizophrenia when the effects of reduced WM task performance in patients with schizophrenia are addressed. Further studies are needed to clarify the pathophysiological basis of WM load sensitivity in schizophrenia and its relationship to genes.
authors.affiliation: Harvard Medical School, Department of Psychiatry, Massachusetts Mental Health Center, Boston, MA 02115, USA. heidi_wencel@hms.harvard.edu
authors.forename: Heidi W
authors.initials: HW
authors.lastname: Thermenos
authors.forename: Jill M
authors.initials: JM
authors.lastname: Goldstein
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Buka
authors.forename: Russell A
authors.initials: RA
authors.lastname: Poldrack
authors.forename: Jennifer K
authors.initials: JK
authors.lastname: Koch
authors.forename: Ming T
authors.initials: MT
authors.lastname: Tsuang
authors.forename: Larry J
authors.initials: LJ
authors.lastname: Seidman
mesh_terms: D000328:Adult; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008569:Memory Disorders / Q000175:diagnosis* / Q000209:etiology*; D009483:Neuropsychological Tests; D010296:Parietal Lobe / Q000503:physiopathology; D017397:Prefrontal Cortex / Q000503:physiopathology*; D012559:Schizophrenia / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology*; D012720:Severity of Illness Index