title: Test-retest reliability and stability of N400 effects in a word-pair semantic priming paradigm.
abstract: OBJECTIVE
  Elicited by any meaningful stimulus, the N400 event-related potential (ERP) component is reduced when the stimulus is related to a preceding one. This N400 semantic priming effect has been used to probe abnormal semantic relationship processing in clinical disorders, and suggested as a possible biomarker for treatment studies. Validating N400 semantic priming effects as a clinical biomarker requires characterizing their test-retest reliability.
  
  
  METHODS
  We assessed test-retest reliability of N400 semantic priming in 16 healthy adults who viewed the same related and unrelated prime-target word pairs in two sessions one week apart.
  
  
  RESULTS
  As expected, N400 amplitudes were smaller for related versus unrelated targets across sessions. N400 priming effects (amplitude differences between unrelated and related targets) were highly correlated across sessions (r=0.85, P<0.0001), but smaller in the second session due to larger N400s to related targets.
  
  
  CONCLUSIONS
  N400 priming effects have high reliability over a one-week interval. They may decrease with repeat testing, possibly because of motivational changes.
  
  
  CONCLUSIONS
  Use of N400 priming effects in treatment studies should account for possible magnitude decreases with repeat testing. Further research is needed to delineate N400 priming effects' test-retest reliability and stability in different age and clinical groups, and with different stimulus types.
authors.affiliation: Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, Ontario, Canada. kiang@mcmaster.ca
authors.forename: Michael
authors.initials: M
authors.lastname: Kiang
authors.forename: Iulia
authors.initials: I
authors.lastname: Patriciu
authors.forename: Carolyn
authors.initials: C
authors.lastname: Roy
authors.forename: Bruce K
authors.initials: BK
authors.lastname: Christensen
authors.forename: Robert B
authors.initials: RB
authors.lastname: Zipursky
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D007802:Language; D008297:Male; D009042:Motivation; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology; D011932:Reading; D015203:Reproducibility of Results; D012660:Semantics; D055815:Young Adult
chemical_list: D015415:Biomarkers