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Elmar T. Schmeisser, Robin R. Vann, Adrienne J. Williams; Nonlinear dynamical characterization of magnocellular neural population response variability. Journal of Vision 2005;5(8):433. doi: 10.1167/5.8.433.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To apply the methods of non-linear dynamical systems analysis (chaos analysis) to neuronal population response variability, using the Visual Evoked Potential (VEP) in glaucoma as a test case for magnocellular function. Methods: 30 s single sweep VEPs in response to 30.3 Hz full field luminance flicker were recorded from 18 volunteers. The volunteers were normal controls, confirmed glaucoma patients, or patients clinically deemed at risk for glaucoma. Power spectral densities (PSD) and fractal dimensions (e.g. D2 via the Grassberger-Procaccia algorithm) were calculated from the data. Results: Normal subjects demonstrated 1/fx (1.4 2 2. Ocular hypertensive patients were partitioned by the results and are being followed for progression. Conclusions: Glaucomatous damage seems to remove the informational content of fast luminance flicker VEP amplitude variability resulting in random amplitude variations rather than well defined, albeit nonlinear chaotic patterns. This may allow an additional diagnostic index more sensitive than the current triumvirate of fields, cups and pressures as well as pointing the way to more sensitive measures for other neural populations.
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