Abstract
Orientation-selective neurons in monkeys and cats show con- trast saturation and contrast-invariant orientation tuning (Albrecht and Hamilton, 1982). Recently proposed models for orientation selectivity predict contrast invariant orientation tuning but no contrast saturation at high strength of recurrent intracortical coupling, whereas at lower cou- pling strengths the contrast response saturates but the tuning widths are contrast dependent (Hansel and Sompolinsky, 1997; Bartsch, Stetter and Obermayer, 1997). In the present work we address the question, if and under which conditions the incorporation of a stochastic distribution of activation thresholds of cortical neurons leads to the saturation of the contrast response curve as a network effect. We find that contrast satu- ration occurs naturally if two different classes of inhibitory inter-neurons are combined. Low threshold inhibition keeps the gain of the cortical amplification finite, whereas high threshold inhibition causes contrast saturation.
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Bartsch, H., Stetter, M., Obermayer, K. (2001). On the Influence of Threshold Variability in a Mean-Field Model of the Visual Cortex. In: Wermter, S., Austin, J., Willshaw, D. (eds) Emergent Neural Computational Architectures Based on Neuroscience. Lecture Notes in Computer Science(), vol 2036. Springer, Berlin, Heidelberg. https://doi.org/10.1007/3-540-44597-8_13
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DOI: https://doi.org/10.1007/3-540-44597-8_13
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