title: Impaired visual cortical plasticity in schizophrenia.
abstract: BACKGROUND
  Impaired cortical plasticity may be part of the core pathophysiology of schizophrenia (SZ). Long-term potentiation is a form of neuroplasticity that has been recently demonstrated in humans by showing that repetitive visual stimulation produces lasting enhancement of visual evoked potentials (VEP). Using this paradigm, we examined whether visual cortical plasticity is impaired in SZ.
  
  
  METHODS
  Electroencephalographic data were recorded from 19 SZ and 22 healthy control (HC) subjects during a visual long-term potentiation paradigm. Visual evoked potentials were elicited by standard visual stimuli (∼.83 Hz, 2-minute blocks) at baseline and at 2, 4, and 20 minutes following exposure to visual high-frequency stimulation (HFS) (∼8.8 Hz, 2 minutes) designed to induce VEP potentiation. To ensure attentiveness during VEP assessments, subjects responded with a button press to infrequent (10%) target stimuli. Visual evoked potentials were subjected to principal components analysis. Two negative-voltage components prominent over occipital-parietal electrode sites were evident at 92 msec (C1) and at 146 msec (N1b). Changes in C1 and N1b component scores from baseline to the post-HFS assessments were compared between groups.
  
  
  RESULTS
  High-frequency stimulation produced sustained potentiation of visual C1 and N1b in HCs but not in SZs. The HCs and SZs had comparable HFS-driven electroencephalographic visual steady state responses. However, greater visual steady state responses to the HFS predicted greater N1b potentiation in HCs but not in SZs. Schizophrenia patients with greater N1b potentiation decreased their reaction times to target stimuli.
  
  
  CONCLUSIONS
  Visual cortical plasticity is impaired in schizophrenia, consistent with hypothesized deficits in N-methyl-D-aspartate receptor function.
authors.affiliation: Department of Psychiatry, Yale University, New Haven, Connecticut.
authors.forename: Idil
authors.initials: I
authors.lastname: Cavuş
authors.forename: Robert M G
authors.initials: RM
authors.lastname: Reinhart
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Roach
authors.forename: Ralitza
authors.initials: R
authors.lastname: Gueorguieva
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Teyler
authors.forename: Wesley C
authors.initials: WC
authors.lastname: Clapp
authors.forename: Judith M
authors.initials: JM
authors.lastname: Ford
authors.forename: John H
authors.initials: JH
authors.lastname: Krystal
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Mathalon
mesh_terms: D000328:Adult; D004569:Electroencephalography; D005074:Evoked Potentials, Visual; D005260:Female; D006801:Humans; D008297:Male; D009473:Neuronal Plasticity; D010775:Photic Stimulation; D011930:Reaction Time; D012559:Schizophrenia / Q000503:physiopathology*; D013997:Time Factors; D014793:Visual Cortex / Q000503:physiopathology*