title: Brain blood flow changes measured by positron emission tomography during an auditory cognitive task in healthy volunteers and in schizophrenic patients.
abstract: OBJECTIVE
  Cognitive deficit is an essential feature of schizophrenia. One of the generally used simple cognitive tasks to characterize specific cognitive dysfunctions is the auditory "oddball" paradigm. During this task, two different tones are presented with different repetition frequencies and the subject is asked to pay attention and to respond to the less frequent tone. The aim of the present study was to apply positron emission tomography (PET) to measure the regional brain blood flow changes induced by an auditory oddball task in healthy volunteers and in stable schizophrenic patients in order to detect activation differences between the two groups.
  
  
  METHODS
  Eight healthy volunteers and 11 schizophrenic patients were studied. The subjects carried out a specific auditory oddball task, while cerebral activation measured via the regional distribution of [15O]-butanol activity changes in the PET camera was recorded.
  
  
  CONCLUSIONS
  Task-related activation differed significantly across the patients and controls. The healthy volunteers displayed significant activation in the anterior cingulate area (Brodman Area - BA32), while in the schizophrenic patients the area was wider, including the mediofrontal regions (BA32 and BA10). The distance between the locations of maximal activation of the two populations were 33 mm and the cluster size was about twice as large in the patient group.
  
  
  CONCLUSIONS
  The present results demonstrate that the perfusion changes induced in the schizophrenic patients by this cognitive task extends over a larger part of the mediofrontal cortex than in the healthy volunteers. The different pattern of activation observed during the auditory oddball task in the schizophrenic patients suggests that a larger cortical area - and consequently a larger variety of neuronal networks--is involved in the cognitive processes in these patients. The dispersion of stimulus processing during a cognitive task requiring sustained attention and stimulus discrimination may play an important role in the pathomechanism of the disorder.
authors.affiliation: PET Center, University of Debrecen, Medical and Health Science Center, Debrecen, Hungary.
authors.forename: Miklós
authors.initials: M
authors.lastname: Emri
authors.forename: Teodóra
authors.initials: T
authors.lastname: Glaub
authors.forename: Roland
authors.initials: R
authors.lastname: Berecz
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Lengyel
authors.forename: Pál
authors.initials: P
authors.lastname: Mikecz
authors.forename: Imre
authors.initials: I
authors.lastname: Repa
authors.forename: Eniko
authors.initials: E
authors.lastname: Bartók
authors.forename: István
authors.initials: I
authors.lastname: Degrell
authors.forename: Lajos
authors.initials: L
authors.lastname: Trón
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D001921:Brain / Q000098:blood supply* / Q000503:physiopathology; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D049268:Positron-Emission Tomography; D012039:Regional Blood Flow / Q000502:physiology*; D012559:Schizophrenia / Q000503:physiopathology*