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Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article Pushing it to the Limit: Adaptation with Dynamically Switching Gain Control | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2007 Article ID 51684 10 pages doi 10.1155 2007 51684 Research Article Pushing it to the Limit Adaptation with Dynamically Switching Gain Control Matthias S. Keil1 and Jordi Vitria1 2 1 Centre de Visi o per Computador Edifici O Campus UAB 08193 Bellaterra Cerdanyola Barcelona Spain 2 Computer Science Department Universitat Autònoma de Barcelona 08193 Bellaterra Cerdanyola Barcelona Spain Received 1 December 2005 Revised 11 July 2006 Accepted 26 August 2006 Recommended by Maria Concetta Morrone With this paper we propose a model to simulate the functional aspects of light adaptation in retinal photoreceptors. Our model however does not link specific stages to the detailed molecular processes which are thought to mediate adaptation in real photoreceptors. We rather model the photoreceptor as a self-adjusting integration device which adds up properly amplified luminance signals. The integration process and the amplification obey a switching behavior that acts to shut down locally the integration process in dependence on the internal state of the receptor. The mathematical structure of our model is quite simple and its computational complexity is quite low. We present results of computer simulations which demonstrate that our model adapts properly to at least four orders of input magnitude. Copyright 2007 M. S. Keil and J. Vitria. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. 1. INTRODUCTION There is agreement that adaptation i.e. the adjustment of sensitivity is important for the function of nervous systems since without corresponding mechanisms any neuron with its limited dynamic range would stay silent or operate in saturation most of the time 1 . Because neurons are noisy devices reliable information transmission is .
