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Variability of responses to sinusoidal modulation

Published online by Cambridge University Press:  02 June 2009

Michael W. Levine
Affiliation:
Department of Psychology and Committee on University of Illinois at Chicago, Chicago

Abstract

Many studies of visual neurons make use of stimuli that are sinusoidally modulated in time, and take as the response the fundamental Fourier component of the firing. This is a study of the variability of the fundamental sinusoidal components.

A theoretical analysis shows that the variance of sinusoidal components should be nearly independent of their amplitudes; this is expected despite the observation that variance of firing rate increases with increasing firing rate. However, this result applies only to the variance of the complex amplitude, defined as the complex Fourier amplitude in response to each stimulus cycle. This variance is called the complex variance. The variance of the scalar amplitude, which is simply the amplitude in response to each stimulus cycle disregarding phase (scalar variance) is expected to shrink by a factor of up to 2⅓ as the response magnitude approaches zero.

If the relationship between variance of rate and rate is linear, complex variance should be independent of amplitude. If the relationship between variance of rate and rate is characterized by a compressive nonlinearity (as has been observed), the complex variance should very slightly decrease with increased amplitude, despite the main trend of increased variance of rate with increased rate.

Data from cat ganglion cells stimulated with sinusoidally modulated lights of various contrasts agree with the theory, although some individual cases show trends that may be indicative of nonlinearity in the relationship between variance of rate and rate.

Type
Research Articles
Copyright
Copyright © Cambridge University Press 1994

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References

Barlow, H.B. & Levick, W.R. (1969). Changes in the maintained discharge with adaptation level in the cat retina. Journal of Physiology 202, 699718.CrossRefGoogle ScholarPubMed
Croner, L.J. & Kaplan, E. (1991). Does receptive field size affect response noise? Investigative Ophthalmology and Visual Science (Suppl.) 32, 905.Google Scholar
Enroth-Cugell, C., Robson, J.G., Schweitzer-Tong, D.E. & Watson, A.B. (1983). Spatio-temporal interactions in cat retinal ganglion cells showing linear spatial summation. Journal of Physiology 341, 279307.CrossRefGoogle ScholarPubMed
Levine, M.W. (1992). Modeling the variability of firing rate of retinal ganglion cells. Mathematical Biosciences 112, 225242.CrossRefGoogle ScholarPubMed
Levine, M.W., Cleland, B.G. & Zimmerman, R.P. (1992). Variability of responses of cat retinal ganglion cells. Visual Neuroscience 8, 277279.CrossRefGoogle ScholarPubMed
Levine, M.W., Frishman, L.J. & Enroth-Cugell, C. (1987). Interactions between the rod and the cone pathways in the cat retina. Vision Research 27, 10931104.CrossRefGoogle ScholarPubMed
Levine, M.W., Zimmerman, R.P. & Carrión-Carire, V. (1988). Variability in responses of retinal ganglion cells. Journal of the Optical Society of America A 5, 593597.CrossRefGoogle ScholarPubMed
Miller, K.S. (1964). Multidimensional Gaussian Distributions. New York: J. Wiley.Google Scholar
Purple, K., Kaplan, E. & Shapley, R.M. (1989). Fluctuations in spontaneous discharge and visual responses in M and P pathways of the macaque monkey. Investigative Ophthalmology and Visual Science (Suppl.) 30, 297.Google Scholar
Snowden, R.J., Treue, S. & Andersen, R.A. (1992). The response of neurons in areas VI and MT of the alert rhesus monkey to moving random dot patterns. Experimental Brain Research 88, 389400.CrossRefGoogle Scholar
Tolhurst, D.J., Movshon, J.A. & Dean, A.F. (1983). The statistical reliability of signals in single neurons in cat and monkey visual cortex. Vision Research 23, 775785.CrossRefGoogle Scholar
Tolhurst, D.J., Movshon, J.A. & Thompson, I.D. (1981). The dependence of response amplitude and variance of cat visual cortical neurones on stimulus contrast. Experimental Brain Research 41, 414419.Google ScholarPubMed