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Documenta Ophthalmologica

, Volume 98, Issue 3, pp 207–232 | Cite as

On the statistical significance of electrophysiological steady-state responses

  • Thomas Meigen
  • Michael Bach
Article

Abstract

Steady-state stimulation is a useful paradigm in many physiologic and clinical situations, for ERG, Pattern-ERG and VEP. One of the advantages is the easy evaluation of the response via Fourier analysis. However, the question whether a given response is statistically significant or not has received little attention so far, although it is especially relevant in high noise, low amplitude recordings, as often occur in pathologic conditions. A given response is statistically significant if it is unlikely that its value is due to noise fluctuations. Thus appropriate estimates of noise and response are required. We have analytically derived formulas for the statistical significance of a given signal-to-noise-ratio s, based on two different estimates of noise: (1) Noise estimate by a `no stimulus' recording, or by a `±average'. The former needs an additional recording, the latter can simultaneously be calculated as the standard average. (2) Noise is estimated as the average of the two neighboring spectral lines (one below, and one above the response frequency). Analytical solutions were obtained for both noise estimates that can easily be evaluated in all appropriate recordings. Noise estimate (1) performs much poorer than noise estimate (2), as can be seen from the following landmark values: Typical significance levels of 5%, 1%, and 0.1% require s values of 4.36, 9.95, and 31.6 (1), and 2.82, 4.55, and 8.40 (2). The noise estimate based on the neighboring frequencies can be easily applied after recording, provided that the noise spectrum is reasonably smooth around the response and frequency-overspill was avoided. It allows a quantitative assessment of low responses in physiological threshold analyses and pathological conditions, e.g., `submicrovolt flicker-ERG'.

ERG signal-to-noise ratio statistical significance steady-state VEP 

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References

  1. 1.
    Alberhseim WJ. A closed-form approximation to Robertson's detection characteristics. Proc IEEE 1981; 69: 839.CrossRefGoogle Scholar
  2. 2.
    Bach M, Gerling J. Retinal and cortical activity in human subjects during color flicker fusion. Vision Res 1992; 32: 1219–23.PubMedCrossRefGoogle Scholar
  3. 3.
    Bach M, Rupp V, Meigen T. Yet another VEP-based visual acuity test. Invest Ophthalmol Vis Sci (ARVO Suppl.) 1998; 39: S184 (Number 879).Google Scholar
  4. 4.
    Birch DG, Sandberg MA. Submicrovolt full-field cone electroretinograms: artifacts and reproducibility. Doc Ophthalmol 1997; 92: 269-80.Google Scholar
  5. 5.
    Harding GFA, Odom JV, Spileers W, Spekreijse H. Standard for visual evoked potentials. Vision Res 1996; 36: 3567–72.PubMedCrossRefGoogle Scholar
  6. 6.
    Kusel R, Wesemann W, Rassow B. A new laser interferometer for the stimulation of pattern-reversal visual evoked potentials. Clin Phys Physiol Meas 1985; 6(3): 239–46.PubMedCrossRefGoogle Scholar
  7. 7.
    Marmor MF, Holder GE, Porciatti V, Trick GL, Zrenner E. Guidelines for basic pattern electroretinography. Recommendations by the International Society for Clinical Electrophysiology of Vision. Doc Ophthalmol 1996; 91: 291–8.CrossRefGoogle Scholar
  8. 8.
    Marmor MF, Zrenner E. Standard for clinical electrophysiology. Doc Ophthalmol 1995; 89: 199–210.PubMedCrossRefGoogle Scholar
  9. 9.
    Mast J, Victor JD. Fluctuations of steady-state VEPs: interaction of driven evoked potentials and the EEG. Electroenceph Clin Neurophysiol 1991; 78: 389–401.PubMedCrossRefGoogle Scholar
  10. 10.
    Morrone C, Porciatti V, Fiorentini A, Burr DC. Pattern-reversal electroretinogram in response to chromatic stimuli: I. Humans. Visual Neurosci 1994; 11: 861–71.CrossRefGoogle Scholar
  11. 11.
    Norcia AM, Tyler CW, Hamer RD, Wesemann W. Measurement of spatial contrast sensitivity with the swept contrast VEP. Vision Res 1989; 29: 627–37.PubMedCrossRefGoogle Scholar
  12. 12.
    Papoulis A. Probability, random variables, and stochastic processes. New York: McGraw-Hill, 1984.Google Scholar
  13. 13.
    Regan D. A study of the visual system by the correlation of light stimuli and evoked electrical responses. Ph.D. thesis, University of London, 1964.Google Scholar
  14. 14.
    Regan D. Some characteristics of average steady-state and transient responses evoked by modulated light. Electroencephal Clin Neurophysiol 1966; 20: 238–48.CrossRefGoogle Scholar
  15. 15.
    Regan D. Human brain electrophysiology. Evoked potentials and evoked magnetic fields in science and medicine. New York, Amsterdam, London: Elsevier, 1989.Google Scholar
  16. 16.
    Rice SO. Statistical properties of a sine wave plus random noise. The Bell System Tech J 1948; 27: 109–57.Google Scholar
  17. 17.
    Robertson GH. Operating characteristics for a linear detector of CW signals in narrowband gaussian noise. The Bell System Tech J 1967; 46: 755–74.Google Scholar
  18. 18.
    Schimmel H.The (±)-reference: Accuracy of estimated mean components in average response studies. Science 1967; 157: 92–4.PubMedGoogle Scholar
  19. 19.
    Sieving PA, Arnold EB, Jamison J, Liepa A, Coats C. Submicrovolt flicker electroretinogram: Cycle-by-cycle recording of multiple harmonics with statistical estimation of measurement uncertainty. Inv Ophthalmol Vis Sci 1998; 39: 1462–9.Google Scholar
  20. 20.
    Simon F, Rassow B. Measurements of spatial interaction and visual acuity using visual evoked potentials elicited by simultaneous multifrequency stimulation. Clin Vision Sci 1986; 1: 287–302.Google Scholar
  21. 21.
    Strasburger H. The analysis of steady state evoked potentials revisited. Clin Vision Sci 1987; 1: 245–56.Google Scholar
  22. 22.
    Strasburger H, Murray IJ, Remky A. Sustained and transient mechanisms in the steadystate visual evoked potential: Onset presentation compared to pattern reversal. Clin. Vision Sci. 1993: 8: 211–34.Google Scholar
  23. 23.
    Victor JD. Mast J. A new statistic for steady-state evoked potentials. Electroenceph Clin Neurophysiol 1991; 78: 378–88PubMedCrossRefGoogle Scholar

Copyright information

© Kluwer Academic Publishers 1999

Authors and Affiliations

  • Thomas Meigen
  • Michael Bach

There are no affiliations available

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