title: High test-retest reliability of checkerboard reversal visual evoked potentials (VEP) over 8 months.
abstract: OBJECTIVE
  The inter-individual variation in the shape of a visual evoked potential (VEP) is large even for simple stimuli. We compared the inter-individual variation in VEP waveform to the intra-individual stability.
  
  
  METHODS
  We recorded VEP with checkerboard stimulation in 10 women aged 19-29years in two sessions. We determined the latencies and the peak-to-peak amplitude of N75 and P100. As a new approach in VEP research, we regressed VEP waveforms pairwise onto each other and calculated a t-value between all sessions. The maximal t-value was taken to indicate recognition for all 19 comparisons performed with one session. The recognition rate was cross-validated in a generalized linear regression model (GLM).
  
  
  RESULTS
  The number of sessions correctly matched to the correct subject was 19 of 20 (true positives) leading to a sensitivity of 95.0% with confidence interval [75.1% 99.9%] for the method. The number of true negatives was 359 of 360 leading to a specificity of 99.7% [98.5% 100.0%].
  
  
  CONCLUSIONS
  The VEP waveform shows high intra-individual stability compared to the inter-individual variation in healthy women.
  
  
  CONCLUSIONS
  With a new statistical approach the effect of external factors on the VEP waveform can now be contrasted against the normal variability over time in longitudinal studies.
authors.affiliation: Neurochirurgische Klinik, UniversitätsSpital Zürich, CH-8091 Zürich, Switzerland. johannes.sarnthein@usz.ch
authors.forename: Johannes
authors.initials: J
authors.lastname: Sarnthein
authors.forename: Maria
authors.initials: M
authors.lastname: Andersson
authors.forename: Michael B
authors.initials: MB
authors.lastname: Zimmermann
authors.forename: Dominik
authors.initials: D
authors.lastname: Zumsteg
mesh_terms: D000328:Adult; D004569:Electroencephalography / Q000379:methods; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D015203:Reproducibility of Results; D014793:Visual Cortex / Q000502:physiology*; D055815:Young Adult