title: Event-related potentials and changes of brain rhythm oscillations during working memory activation in patients with first-episode psychosis.
abstract: BACKGROUND
  Earlier contributions have documented significant changes in sensory, attention-related endogenous event-related potential (ERP) components and θ band oscillatory responses during working memory activation in patients with schizophrenia. In patients with first-episode psychosis, such studies are still scarce and mostly focused on auditory sensory processing. The present study aimed to explore whether subtle deficits of cortical activation are present in these patients before the decline of working memory performance.
  
  
  METHODS
  We assessed exogenous and endogenous ERPs and frontal θ event-related synchronization (ERS) in patients with first-episode psychosis and healthy controls who successfully performed an adapted 2-back working memory task, including 2 visual n-backworking memory tasks as well as oddball detection and passive fixation tasks.
  
  
  RESULTS
  We included 15 patients with first-episode psychosis and 18 controls in this study. Compared with controls, patients with first-episode psychosis displayed increased latencies of early visual ERPs and phasic θ ERS culmination peak in all conditions. However, they also showed a rapid recruitment of working memory-related neural generators, even in pure attention tasks, as indicated by the decreased N200 latency and increased amplitude of sustained θ ERS in detection compared with controls.
  
  
  CONCLUSIONS
  Owing to the limited sample size, no distinction was made between patients with first-episode psychosis with positive and negative symptoms. Although we controlled for the global load of neuroleptics, medication effect cannot be totally ruled out.
  
  
  CONCLUSIONS
  The present findings support the concept of a blunted electroencephalographic response in patients with first-episode psychosis who recruit the maximum neural generators in simple attention conditions without being able to modulate their brain activation with increased complexity of working memory tasks.
authors.affiliation: Department of Psychiatry, Geneva University Hospitals and University of Geneva, Switzerland. pascal.missonnier-evrard@hcuge.ch
authors.forename: Pascal
authors.initials: P
authors.lastname: Missonnier
authors.forename: François R
authors.initials: FR
authors.lastname: Herrmann
authors.forename: Adriano
authors.initials: A
authors.lastname: Zanello
authors.forename: Maryse
authors.initials: M
authors.lastname: Badan Bâ
authors.forename: Logos
authors.initials: L
authors.lastname: Curtis
authors.forename: Diana
authors.initials: D
authors.lastname: Canovas
authors.forename: Fabrice
authors.initials: F
authors.lastname: Chantraine
authors.forename: Jonas
authors.initials: J
authors.lastname: Richiardi
authors.forename: Panteleimon
authors.initials: P
authors.lastname: Giannakopoulos
authors.forename: Marco C G
authors.initials: MC
authors.lastname: Merlo
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000502:physiology*; D003627:Data Interpretation, Statistical; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004569:Electroencephalography; D058407:Electroencephalography Phase Synchronization; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D005403:Fixation, Ocular; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D010775:Photic Stimulation; D011618:Psychotic Disorders / Q000503:physiopathology* / Q000523:psychology*; D011930:Reaction Time / Q000502:physiology; D055815:Young Adult