Geisel, Theo

[["dc.contributor.author","Wolf, Fred"],["dc.contributor.author","Pawelzik, Klaus"],["dc.contributor.author","Geisel, Theo"],["dc.contributor.author","Kim, Douglas S."],["dc.contributor.author","Bonhoeffer, Tobias"],["dc.contributor.editor","Gielen, S."],["dc.contributor.editor","Kappen, B."],["dc.date.accessioned","2017-09-07T11:46:18Z"],["dc.date.available","2017-09-07T11:46:18Z"],["dc.date.issued","2012"],["dc.description.abstract","We propose a mathematical description for the spatial organization of orientation preference in the visual cortex. In this approach the spatial pattern of orientation preference is predicted from position and chirality of its singularities (i.e. ”pinwheels”). The theory is derived from a few phenomenological principles characterizing the qualitative structure of orientation maps under the requirement of mathematical simplicity. A comparison with optically recorded images of cortical maps suggests that orientation preference can be predicted over a much larger spatial range than previously estimated on the basis of correlation measurements."],["dc.identifier.doi","10.1007/978-1-4471-2063-6_30"],["dc.identifier.gro","3151879"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/8711"],["dc.language.iso","en"],["dc.notes.status","public"],["dc.notes.submitter","chake"],["dc.publisher","Springer"],["dc.publisher.place","London"],["dc.relation.isbn","978-3-540-19839-0"],["dc.relation.ispartof","ICANN ’93"],["dc.title","Map Structure from Pinwheel Position"],["dc.type","book_chapter"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","no"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","016804"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Physical Review Letters"],["dc.bibliographiccitation.volume","89"],["dc.contributor.author","Fleischmann, Ragnar"],["dc.contributor.author","Geisel, Theo"],["dc.date.accessioned","2018-11-07T10:23:48Z"],["dc.date.available","2018-11-07T10:23:48Z"],["dc.date.issued","2002"],["dc.description.abstract","Recent experiments on symmetry-broken mesoscopic semiconductor structures have exhibited an amazing rectifying effect in the transverse current-voltage characteristics with promising prospects for future applications. We present a simple microscopic model, which takes into account the energy dependence of current-carrying modes and explains the rectifying effect by an interplay of fully quantized and quasiclassical transport channels in the system. It also suggests the design of a ballistic rectifier with an optimized rectifying signal and predicts voltage oscillations which may provide an experimental test for the mechanism considered here."],["dc.identifier.doi","10.1103/PhysRevLett.89.016804"],["dc.identifier.isi","000176285700040"],["dc.identifier.pmid","12097062"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/42533"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","American Physical Soc"],["dc.relation.issn","0031-9007"],["dc.title","Mesoscopic rectifiers based on ballistic transport"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","87"],["dc.bibliographiccitation.journal","Frontiers in computational neuroscience"],["dc.bibliographiccitation.lastpage","87"],["dc.bibliographiccitation.volume","7"],["dc.contributor.author","Uhlig, Maximilian"],["dc.contributor.author","Levina, Anna"],["dc.contributor.author","Geisel, Theo"],["dc.contributor.author","Herrmann, J. Michael"],["dc.date.accessioned","2019-07-09T11:40:06Z"],["dc.date.available","2019-07-09T11:40:06Z"],["dc.date.issued","2013"],["dc.description.abstract","Critical behavior in neural networks is characterized by scale-free avalanche size distributions and can be explained by self-regulatory mechanisms. Theoretical and experimental evidence indicates that information storage capacity reaches its maximum in the critical regime. We study the effect of structural connectivity formed by Hebbian learning on the criticality of network dynamics. The network only endowed with Hebbian learning does not allow for simultaneous information storage and criticality. However, the critical regime can be stabilized by short-term synaptic dynamics in the form of synaptic depression and facilitation or, alternatively, by homeostatic adaptation of the synaptic weights. We show that a heterogeneous distribution of maximal synaptic strengths does not preclude criticality if the Hebbian learning is alternated with periods of critical dynamics recovery. We discuss the relevance of these findings for the flexibility of memory in aging and with respect to the recent theory of synaptic plasticity."],["dc.identifier.doi","10.3389/fncom.2013.00087"],["dc.identifier.fs","597034"],["dc.identifier.pmid","23898261"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/10673"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/58094"],["dc.language.iso","en"],["dc.notes","This work is supported by the Federal Ministry of \r\nEducation and Research(BMBF)Germany under grant number \r\n01GQ1005B."],["dc.notes.intern","Merged from goescholar"],["dc.relation.issn","1662-5188"],["dc.relation.orgunit","Fakultät für Physik"],["dc.rights","Goescholar"],["dc.rights.access","openAccess"],["dc.rights.uri","https://goedoc.uni-goettingen.de/licenses"],["dc.title","Critical dynamics in associative memory networks."],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1706"],["dc.bibliographiccitation.issue","10-12"],["dc.bibliographiccitation.journal","Neurocomputing"],["dc.bibliographiccitation.lastpage","1710"],["dc.bibliographiccitation.volume","70"],["dc.contributor.author","Schrobsdorff, Hecke"],["dc.contributor.author","Herrmann, J. Michael"],["dc.contributor.author","Geisel, Theo"],["dc.date.accessioned","2018-11-07T11:02:05Z"],["dc.date.available","2018-11-07T11:02:05Z"],["dc.date.issued","2007"],["dc.description.abstract","We study a model of feature binding in prefrontal cortex which defers specific perceptual information to lower areas and merely maintains the identity of the combination. The model consists of three layers of pulse-coupled leaky integrate-and-fire neurons. Features are encoded by the location of sustained activity in the subordinate layers. The feature layers are excitatorily coupled to a superordinate layer that represents combinations of features by means of an oscillatory dynamics. The model accounts for effects such as the memorization of an object that was perceived only for a short period, illusory binding of simultaneous stimuli, and the limit of attentional capacity. The present paper discusses conditions for localized excitations in networks of integrate-and-fire neurons and considers the application to a dynamic link architecture. (c) 2006 Elsevier B.V. All rights reserved."],["dc.identifier.doi","10.1016/j.neucom.2006.10.049"],["dc.identifier.isi","000247215300023"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/51296"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Elsevier Science Bv"],["dc.publisher.place","Amsterdam"],["dc.relation.conference","15th Annual Computational Neuroscience Meeting"],["dc.relation.eventlocation","Edinburgh, SCOTLAND"],["dc.relation.issn","0925-2312"],["dc.title","A feature-binding model with localized excitations"],["dc.type","conference_paper"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1335"],["dc.bibliographiccitation.journal","Neurocomputing"],["dc.bibliographiccitation.lastpage","1339"],["dc.bibliographiccitation.volume","38-40"],["dc.contributor.author","Kaschube, Matthias"],["dc.contributor.author","Wolf, Fred"],["dc.contributor.author","Geisel, Theo"],["dc.contributor.author","Löwel, Siegrid"],["dc.date.accessioned","2017-09-07T11:46:12Z"],["dc.date.available","2017-09-07T11:46:12Z"],["dc.date.issued","2001"],["dc.description.abstract","Our visual system preferentially groups contour segments that not only have the same orientation but are colinear as well. Long-range horizontal connections are thought to play an important role in context-dependent modifications of neuronal responses. Since the topology of these connections shows a close relation to the perceptual grouping criterion of colinearity, we tested whether the statistical properties of real world images are biased towards colinear contours. By wavelet analysis we detected contours in images of natural environments and calculated their spatial correlations. In urban as well as in natural environments, the correlations between colinear contour segments were larger than the correlations for parallel contour segments. These observations indicate that colinear contour segments dominate real world images and thus might bias the functional and structural development of our visual system."],["dc.identifier.doi","10.1016/s0925-2312(01)00493-3"],["dc.identifier.gro","3151855"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/8684"],["dc.language.iso","en"],["dc.notes.status","final"],["dc.relation.issn","0925-2312"],["dc.subject","Image analysis; Natural scenes; Wavelets; Visual cortex"],["dc.title","The prevalence of colinear contours in the real world"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","no"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","023621"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","PHYSICAL REVIEW A"],["dc.bibliographiccitation.volume","79"],["dc.contributor.author","Hiller, Moritz"],["dc.contributor.author","Kottos, Tsampikos"],["dc.contributor.author","Geisel, Theo"],["dc.date.accessioned","2018-11-07T08:33:16Z"],["dc.date.available","2018-11-07T08:33:16Z"],["dc.date.issued","2009"],["dc.description.abstract","We study the energy redistribution of interacting bosons in a ring-shaped quantum trimer as the coupling strength between neighboring sites of the corresponding Bose-Hubbard Hamiltonian undergoes a sudden change delta k. Our analysis is based on a threefold approach combining linear response theory calculations as well as semiclassical and random matrix theory considerations. The delta k borders of applicability of each of these methods are identified by direct comparison with the exact quantum-mechanical results. We find that while the variance of the evolving quantum distribution shows a remarkable quantum-classical correspondence (QCC) for all delta k values, other moments exhibit this QCC only in the nonperturbative delta k regime."],["dc.description.sponsorship","United States-Israel Binational Science Foundation (BSF); DFG"],["dc.identifier.doi","10.1103/PhysRevA.79.023621"],["dc.identifier.isi","000263815000135"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/17535"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Physical Soc"],["dc.relation.issn","1094-1622"],["dc.relation.issn","1050-2947"],["dc.title","Wave-packet dynamics in energy space of a chaotic trimeric Bose-Hubbard system"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","063034"],["dc.bibliographiccitation.journal","New Journal of Physics"],["dc.bibliographiccitation.volume","15"],["dc.contributor.author","Lukovic, Mirko"],["dc.contributor.author","Geisel, Theo"],["dc.contributor.author","Eule, Stephan"],["dc.date.accessioned","2018-11-07T09:23:36Z"],["dc.date.available","2018-11-07T09:23:36Z"],["dc.date.issued","2013"],["dc.description.abstract","We investigate the geometric properties of two-dimensional continuous time random walks that are used extensively to model stochastic processes exhibiting anomalous diffusion in a variety of different fields. Using the concept of subordination, we determine exact analytical expressions for the average perimeter and area of the convex hulls for this class of non-Markovian processes. As the convex hull is a simple measure to estimate the home range of animals, our results give analytical estimates for the home range of foraging animals that perform sub-diffusive search strategies such as some Mediterranean seabirds and animals that ambush their prey. We also apply our results to Levy flights where possible."],["dc.description.sponsorship","IMPRS-pbcs"],["dc.identifier.doi","10.1088/1367-2630/15/6/063034"],["dc.identifier.fs","597030"],["dc.identifier.isi","000320698800005"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/10560"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/29622"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Iop Publishing Ltd"],["dc.relation.issn","1367-2630"],["dc.relation.orgunit","Fakultät für Physik"],["dc.rights","CC BY 3.0"],["dc.title","Area and perimeter covered by anomalous diffusion processes"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","015108"],["dc.bibliographiccitation.firstpage","1"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Chaos: An Interdisciplinary Journal of Nonlinear Science"],["dc.bibliographiccitation.lastpage","16"],["dc.bibliographiccitation.volume","16"],["dc.contributor.author","Timme, Marc"],["dc.contributor.author","Geisel, Theo"],["dc.contributor.author","Wolf, Fred"],["dc.date.accessioned","2017-09-07T11:46:16Z"],["dc.date.available","2017-09-07T11:46:16Z"],["dc.date.issued","2006"],["dc.description.abstract","We analyze the dynamics of networks of spiking neural oscillators. First, we present an exact linear stability theory of the synchronous state for networks of arbitrary connectivity. For general neuron rise functions, stability is determined by multiple operators, for which standard analysis is not suitable. We describe a general nonstandard solution to the multioperator problem. Subsequently, we derive a class of neuronal rise functions for which all stability operators become degenerate and standard eigenvalue analysis becomes a suitable tool. Interestingly, this class is found to consist of networks of leaky integrate-and-fire neurons. For random networks of inhibitory integrate-and-fire neurons, we then develop an analytical approach, based on the theory of random matrices, to precisely determine the eigenvalue distributions of the stability operators. This yields the asymptotic relaxation time for perturbations to the synchronous state which provides the characteristic time scale on which neurons can coordinate their activity in such networks. For networks with finite in-degree, i.e., finite number of presynaptic inputs per neuron, we find a speed limit to coordinating spiking activity. Even with arbitrarily strong interaction strengths neurons cannot synchronize faster than at a certain maximal speed determined by the typical in-degree.The individual units of many physical systems, from the planets of our solar system to the atoms in a solid, typically interact continuously in time and without significant delay. Thus at every instant of time such a unit is influenced by the current state of its interaction partners. Moreover, particles of many-body systems are often considered to have very simple lattice topology (as in a crystal) or no prescribed topology at all (as in an ideal gas). Many important biological systems are drastically different: their units are interacting by sending and receiving pulses at discrete instances of time. Furthermore, biological systems often exhibit significant delays in the couplings and very complicated topologies of their interaction networks. Examples of such systems include neurons, which interact by stereotyped electrical pulses called action potentials or spikes; crickets, which chirp to communicate acoustically; populations of fireflies that interact by short light pulses. The combination of pulse-coupling, delays, and complicated network topology formally makes the dynamical system to be investigated a high dimensional, heterogeneous nonlinear hybrid system with delays. Here we present an exact analysis of aspects of the dynamics of such networks in the case of simple one-dimensional nonlinear interacting units. These systems are simple models for the collective dynamics of recurrent networks of spiking neurons. After briefly presenting stability results for the synchronous state, we show how to use the theory of random matrices to analytically predict the eigenvalue distribution of stability matrices and thus derive the speed of synchronization in terms of dynamical and network parameters. We find that networks of neural oscillators typically exhibit speed limits and cannot synchronize faster than a certain bound defined by the network topology."],["dc.identifier.doi","10.1063/1.2150775"],["dc.identifier.gro","3151890"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/8722"],["dc.language.iso","en"],["dc.notes.status","final"],["dc.notes.submitter","chake"],["dc.relation.issn","1054-1500"],["dc.title","Speed of synchronization in complex networks of neural oscillators: Analytic results based on Random Matrix Theory"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","no"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","821"],["dc.contributor.author","Timme, Marc"],["dc.contributor.author","Geisel, Theo"],["dc.contributor.author","Wolf, F."],["dc.date.accessioned","2017-11-21T15:34:02Z"],["dc.date.available","2017-11-21T15:34:02Z"],["dc.date.issued","2001"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/10167"],["dc.language.iso","en"],["dc.notes.status","final"],["dc.relation.eventend","2001-11-15"],["dc.relation.eventlocation","San Diego"],["dc.relation.eventstart","2001-11-10"],["dc.relation.ispartof","Society for Neuroscience Abstracts"],["dc.title","Synchronization and Desynchronization in Neural Networks with General Connectivity"],["dc.type","conference_abstract"],["dc.type.internalPublication","unknown"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","367"],["dc.bibliographiccitation.journal","Neurocomputing"],["dc.bibliographiccitation.lastpage","374"],["dc.bibliographiccitation.volume","26-27"],["dc.contributor.author","Ernst, Udo"],["dc.contributor.author","Pawelzik, Klaus"],["dc.contributor.author","Wolf, Fred"],["dc.contributor.author","Geisel, Theo"],["dc.date.accessioned","2017-09-07T11:46:13Z"],["dc.date.available","2017-09-07T11:46:13Z"],["dc.date.issued","1999"],["dc.description.abstract","In many experiments it has been found that stimuli outside the classical receptive-field of orientation-selective cells in the visual cortex can strongly modulate the response properties of these cells. Typically, stimuli with orientation contrasts lead to enhancement, whereas iso-orientation stimuli lead to suppression of the neuronal activity, but these phenomena in general depend in a complicate manner on various parameters like stimulus configuration, contrast, and geometry. In this contribution, we develop a simple theory for such non-classical receptive-field phenomena. We explain the basic mechanisms by a fixed-point analysis. Within this analysis, center-surround experiments can be described by trajectories in parameter space. This allows for a systematic variation of the coupling and stimulation constants. We show that the strength or sign of the enhancement or suppression should not only vary with the experimental paradigm but also with the position of the cell within the cortex. Our results suggest that non-classical receptive-field phenomena are mediated through orientation-specific lateral excitatory interactions."],["dc.identifier.doi","10.1016/s0925-2312(99)00026-0"],["dc.identifier.gro","3151865"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/8695"],["dc.language.iso","en"],["dc.notes.status","final"],["dc.relation.issn","0925-2312"],["dc.subject","Receptive fields; Visual cortex; Orientation contrast sensitivity; Fixed-point analysis; Center-surround phenomena"],["dc.title","Theory of non-classical receptive field phenomena in the visual cortex"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","no"],["dspace.entity.type","Publication"]]