Publications by authors named "Andreas B Sichert"

5 Publications

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Optimality in mono- and multisensory map formation.

Biol Cybern 2010 Jul 26;103(1):1-20. Epub 2010 May 26.

Technical University of Munich, Munich, Germany.

In the struggle for survival in a complex and dynamic environment, nature has developed a multitude of sophisticated sensory systems. In order to exploit the information provided by these sensory systems, higher vertebrates reconstruct the spatio-temporal environment from each of the sensory systems they have at their disposal. That is, for each modality the animal computes a neuronal representation of the outside world, a monosensory neuronal map. Here we present a universal framework that allows to calculate the specific layout of the involved neuronal network by means of a general mathematical principle, viz., stochastic optimality. In order to illustrate the use of this theoretical framework, we provide a step-by-step tutorial of how to apply our model. In so doing, we present a spatial and a temporal example of optimal stimulus reconstruction which underline the advantages of our approach. That is, given a known physical signal transmission and rudimental knowledge of the detection process, our approach allows to estimate the possible performance and to predict neuronal properties of biological sensory systems. Finally, information from different sensory modalities has to be integrated so as to gain a unified perception of reality for further processing, e.g., for distinct motor commands. We briefly discuss concepts of multimodal interaction and how a multimodal space can evolve by alignment of monosensory maps.
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http://dx.doi.org/10.1007/s00422-010-0393-7DOI Listing
July 2010

How stimulus shape affects lateral-line perception: analytical approach to analyze natural stimuli characteristics.

Biol Cybern 2010 Mar 4;102(3):177-80. Epub 2010 Mar 4.

Physik Department T35 & BCCN-Munich, Technische Universität München, 85747, Garching bei München, Germany.

We revisit the method of conformal mapping and apply it to the setting found in mechanosensory detection systems such as the lateral-line system of fish. We derive easy-to-use equations capable of describing analytically the influence of the stimulus shape on the flow field and thus on the input to the lateral line. The present approach shows that the shape of a submerged moving object affects its perception if its distance to a detecting animal does not exceed the object's body length.
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http://dx.doi.org/10.1007/s00422-010-0369-7DOI Listing
March 2010

Hydrodynamic object recognition: when multipoles count.

Phys Rev Lett 2009 Feb 6;102(5):058104. Epub 2009 Feb 6.

Physik Department T35 & Bernstein Center for Computational Neuroscience-Munich, Technische Universität München, 85747 Garching bei München, Germany.

The lateral-line system is a unique mechanosensory facility of aquatic animals that enables them not only to localize prey, predator, obstacles, and conspecifics, but also to recognize hydrodynamic objects. Here we present an explicit model explaining how aquatic animals such as fish can distinguish differently shaped submerged moving objects. Our model is based on the hydrodynamic multipole expansion and uses the unambiguous set of multipole components to identify the corresponding object. Furthermore, we show that within the natural range of one fish length the velocity field contains far more information than that due to a dipole. Finally, the model we present is easy to implement both neuronally and technically, and agrees well with available neuronal, physiological, and behavioral data on the lateral-line system.
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http://dx.doi.org/10.1103/PhysRevLett.102.058104DOI Listing
February 2009

Snake's perspective on heat: reconstruction of input using an imperfect detection system.

Phys Rev Lett 2006 Aug 9;97(6):068105. Epub 2006 Aug 9.

Physik Department, Technische Universität München, 85747 Garching bei München, Germany.

Two groups of snakes possess an infrared detection system that is used to create a heat image of their environment. In this Letter we present an explicit reconstruction model, the "virtual lens," which explains how a snake can overcome the optical limitations of a wide aperture pinhole camera, and how ensuing properties of the receptive fields on the infrared-sensitive membrane may explain the behavioral performance of this sensory system. Our model explores the optical quality of the infrared system by detailing how a functional representation of the thermal properties of the environment can be created. The model is easy to implement neuronally and agrees well with available neuronal, physiological, and behavioral data on the snake infrared system.
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http://dx.doi.org/10.1103/PhysRevLett.97.068105DOI Listing
August 2006

Estimating position and velocity of a submerged moving object by the clawed frog Xenopus and by fish--a cybernetic approach.

Biol Cybern 2005 Oct 19;93(4):231-8. Epub 2005 Oct 19.

Physik Department, TU München, 85747, Garching bei München, Germany.

The lateral-line system is a unique facility of aquatic animals to locate predator, prey, or conspecifics. We present a detailed model of how the clawed frog Xenopus, or fish, can localize submerged moving objects in three dimensions by using their lateral-line system. In so doing we develop two models of a slightly different nature. First, we exploit the characteristic properties of the velocity field, such as zeros and maxima or minima, that a moving object generates at the lateral-line organs and that are directly accessible neuronally, in the context of a simplified geometry. In addition, we show that the associated neuronal model is robust with respect to noise. Though we focus on the superficial neuromasts of Xenopus the same arguments apply mutatis mutandis to the canal lateral-line system of fish. Second, we present a full-blown three-dimensional reconstruction of the source on the basis of a maximum likelihood argument.
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http://dx.doi.org/10.1007/s00422-005-0005-0DOI Listing
October 2005
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