title: Reduced auditory evoked gamma band response and cognitive processing deficits in first episode schizophrenia.
abstract: OBJECTIVE
  Gamma-band oscillations (e.g., the early auditory evoked gamma-band response, aeGBR) have been suggested to mediate cognitive and perceptual processes by driving the synchronization of local neuronal populations. Reduced aeGBR is a consistent finding in patients with schizophrenia and high-risk subjects, and has been proposed to represent an endophenotype for the illness. However, it is still unclear whether this reduction represents a deficit in sensory or cognitive processes, or a combination of the two. The present study investigated this question by manipulating the difficulty of an auditory reaction task in patients with first-episode schizophrenia and healthy controls.
  
  
  METHODS
  A 64-channel EEG was recorded in 23 patients with first-episode schizophrenia and 22 healthy controls during two conditions of an auditory reaction task: an easy condition that merely required low-level vigilance, and a difficult condition that placed significant demands on attention and working memory.
  
  
  RESULTS
  In contrast to healthy controls, patients failed to increase aeGBR power and phase-locking in the difficult condition. In patients, aeGBR power and phase-locking indices were associated with working memory deficits.
  
  
  CONCLUSIONS
  The observed results confirm the applicability of aeGBR disturbances as a stable endophenotype of schizophrenia, and suggest a cognitive, rather than sensory, deficit at their origin.
authors.affiliation: a Department of Psychiatry and Psychotherapy , Psychiatry Neuroimaging Branch (PNB), University Medical Center Hamburg-Eppendorf , Hamburg , Germany.
authors.forename: Gregor
authors.initials: G
authors.lastname: Leicht
authors.affiliation: a Department of Psychiatry and Psychotherapy , Psychiatry Neuroimaging Branch (PNB), University Medical Center Hamburg-Eppendorf , Hamburg , Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Andreou
authors.affiliation: a Department of Psychiatry and Psychotherapy , Psychiatry Neuroimaging Branch (PNB), University Medical Center Hamburg-Eppendorf , Hamburg , Germany.
authors.forename: Nenad
authors.initials: N
authors.lastname: Polomac
authors.affiliation: a Department of Psychiatry and Psychotherapy , Psychiatry Neuroimaging Branch (PNB), University Medical Center Hamburg-Eppendorf , Hamburg , Germany.
authors.forename: Clarissa
authors.initials: C
authors.lastname: Lanig
authors.affiliation: b Department of Psychiatry and Psychotherapy , University Medical Center Hamburg-Eppendorf , Hamburg , Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Schöttle
authors.affiliation: b Department of Psychiatry and Psychotherapy , University Medical Center Hamburg-Eppendorf , Hamburg , Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Lambert
authors.affiliation: a Department of Psychiatry and Psychotherapy , Psychiatry Neuroimaging Branch (PNB), University Medical Center Hamburg-Eppendorf , Hamburg , Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Mulert
keywords: EEG; auditory; first episode; gamma; schizophrenia