Adaptation Effects in the Transient Visual Evoked Potential
Implicit in the measurement of the averaged transient visual evoked potential (VEP) is the assumption that the visual system returns to a state of rest between stimuli. A signal enhancement technique such as averaging should display the signal which is the technique itself. Hence the temporal characteristics (stimulus duration and presentation rate) of the stimulus regime should be such that the above assumption is valid, or the averaging procedure may itself alter that which it seeks to measure. A lower limit to the rate of stimulation is effectively set by the stationarity of the background EEG (Cohen and Sances, 1977), and by the difficulty of maintaining a constant psychological state over periods of more than a few seconds. The upper limit is set by the transition to a steady state VEP, when the individual components become indistinguishable. Between these limits there is considerable scope for variation. The aim of this study is to investigate the dependence of the averaged transient VEP upon temporal stimulus parameters, with particular reference to the effects of adaptation upon the components of the pattern VEP.
KeywordsStimulus Duration Interstimulus Interval Visual Evoke Potential Pattern Onset Check Size
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- Arden, G.B., Faulkner, D.J. and Mair, C. A versatile television pattern generator for visual evoked potentials. In J.E. Desmedt (Ed.) Visual Evoked Potentials in Man; New Developments, Oxford: Clarendon Press, 1977.Google Scholar
- Fraise, P. Les Structures Rythmiques, Paris: Erasme, 1956.Google Scholar
- James, C.R. and Jeffreys, D.A. Properties of individual components of pattern-onset evoked potentials in man. J. Physiol., 1975, 249, 57–58P.Google Scholar
- Jeffreys, D.A. The physiological significance of pattern visual evoked potentials. In J.E. Desmedt (Ed.), Visual Evoked Potentials in Man; New Developments. Oxford; Clarendon Press, 1977.Google Scholar
- Kulikowski, J. Visual evoked potentials as a measure of visibility. In J.E. Desmedt (Ed.), visual Evoked Potentials in Man: New Developments, Oxford: Clarendon Press, 1977.Google Scholar