Project acronym FRU CIRCUIT
Project Neural basis of Drosophila mating behaviours
Researcher (PI) Barry Dickson
Host Institution (HI) FORSCHUNGSINSTITUT FUR MOLEKULARE PATHOLOGIE GESELLSCHAFT MBH
Call Details Advanced Grant (AdG), LS5, ERC-2008-AdG
Summary How does information processing in neural circuits generate behaviour? Answering this question requires identifying each of the distinct neuronal types that contributes to a behaviour, defining their anatomy and connectivity, and establishing causal relationships between their activity, the activity of other neurons in the circuit, and the behaviour. Here, I propose such an analysis of the neural circuits that guide Drosophila mating behaviours. The distinct mating behaviours of males and females are genetically pre-programmed, yet can also be modified by experience. The set of ~2000 neurons that express the fru gene have been intimately linked to both male and female mating behaviours. This set of neurons includes specific sensory, central, and motor neurons, at least some of which are directly connected. Male-specific fruM isoforms configure this circuit developmentally for male rather than female behaviour. In females, mating triggers a biochemical cascade that reconfigures the circuit for post-mating rather than virgin female behaviour. We estimate that there are ~100 distinct classes of fru neuron. Using genetic and optical tools, we aim to identify each distinct class of fru neuron and to define its anatomy and connectivity. By silencing or activating specific neurons, or changing their genetic sex, we will assess their contributions to male and female behaviours, and how these perturbations impinge on activity patterns in other fru neurons. We also aim to define how a specific experience can modify the physiological properties of these circuits, and how these changes in turn modulate mating behaviour. These studies will define the operating principles of these neural circuits, contributing to a molecules-to-systems explanation of Drosophila s mating behaviours.
Summary
How does information processing in neural circuits generate behaviour? Answering this question requires identifying each of the distinct neuronal types that contributes to a behaviour, defining their anatomy and connectivity, and establishing causal relationships between their activity, the activity of other neurons in the circuit, and the behaviour. Here, I propose such an analysis of the neural circuits that guide Drosophila mating behaviours. The distinct mating behaviours of males and females are genetically pre-programmed, yet can also be modified by experience. The set of ~2000 neurons that express the fru gene have been intimately linked to both male and female mating behaviours. This set of neurons includes specific sensory, central, and motor neurons, at least some of which are directly connected. Male-specific fruM isoforms configure this circuit developmentally for male rather than female behaviour. In females, mating triggers a biochemical cascade that reconfigures the circuit for post-mating rather than virgin female behaviour. We estimate that there are ~100 distinct classes of fru neuron. Using genetic and optical tools, we aim to identify each distinct class of fru neuron and to define its anatomy and connectivity. By silencing or activating specific neurons, or changing their genetic sex, we will assess their contributions to male and female behaviours, and how these perturbations impinge on activity patterns in other fru neurons. We also aim to define how a specific experience can modify the physiological properties of these circuits, and how these changes in turn modulate mating behaviour. These studies will define the operating principles of these neural circuits, contributing to a molecules-to-systems explanation of Drosophila s mating behaviours.
Max ERC Funding
2 492 164 €
Duration
Start date: 2009-07-01, End date: 2013-09-30
Project acronym GEMIS
Project Generalized Homological Mirror Symmetry and Applications
Researcher (PI) Ludmil Katzarkov
Host Institution (HI) UNIVERSITAT WIEN
Call Details Advanced Grant (AdG), PE1, ERC-2008-AdG
Summary Mirror symmetry arose originally in physics, as a duality between $N = 2$ superconformal field theories. Witten formulated a more mathematically accessible version, in terms of topological field theories. Both conformal and topological field theories can be defined axiomatically, but more interestingly, there are several geometric ways of constructing them. A priori, the mirror correspondence is not unique, and it does not necessarily remain within a single class of geometric models. The classical case relates $\sigma$-models, but in a more modern formulation, one has mirror dualities between different Landau-Ginzburg models, as well as between such models and $\sigma$-models; orbifolds should also be included in this. The simplest example would be the function $W: \C \rightarrow \C$, $W(x) = x^{n+1}$, which is self-mirror (up to dividing by the $\bZ/n+1$ symmetry group, in an orbifold sense). While the mathematics of the $\sigma$-model mirror correspondence is familiar by now, generalizations to Landau-Ginzburg theories are only beginning to be understood. Today it is clear that Homologcal Mirror Symmetry (HMS) as a categorical correspondence works and it is time for developing direct geometric applications to classical problems - rationality of algebraic varieties and Hodge conjecture. This the main goal of the proposal. But in order to attack the above problems we need to generalize HMS and explore its connection to new developments in modern Hodge theory. In order to carry the above program we plan to further already working team Vienna, Paris, Moscow, MIT.
Summary
Mirror symmetry arose originally in physics, as a duality between $N = 2$ superconformal field theories. Witten formulated a more mathematically accessible version, in terms of topological field theories. Both conformal and topological field theories can be defined axiomatically, but more interestingly, there are several geometric ways of constructing them. A priori, the mirror correspondence is not unique, and it does not necessarily remain within a single class of geometric models. The classical case relates $\sigma$-models, but in a more modern formulation, one has mirror dualities between different Landau-Ginzburg models, as well as between such models and $\sigma$-models; orbifolds should also be included in this. The simplest example would be the function $W: \C \rightarrow \C$, $W(x) = x^{n+1}$, which is self-mirror (up to dividing by the $\bZ/n+1$ symmetry group, in an orbifold sense). While the mathematics of the $\sigma$-model mirror correspondence is familiar by now, generalizations to Landau-Ginzburg theories are only beginning to be understood. Today it is clear that Homologcal Mirror Symmetry (HMS) as a categorical correspondence works and it is time for developing direct geometric applications to classical problems - rationality of algebraic varieties and Hodge conjecture. This the main goal of the proposal. But in order to attack the above problems we need to generalize HMS and explore its connection to new developments in modern Hodge theory. In order to carry the above program we plan to further already working team Vienna, Paris, Moscow, MIT.
Max ERC Funding
1 060 800 €
Duration
Start date: 2009-01-01, End date: 2013-12-31
Project acronym HIPPOCHRONOCIRCUITRY
Project The chronocircuitry of the hippocampus during cognitive behaviour
Researcher (PI) Thomas Klausberger
Host Institution (HI) MEDIZINISCHE UNIVERSITAET WIEN
Call Details Starting Grant (StG), LS5, ERC-2009-StG
Summary Neuronal activity of pyramidal cells in the CA1 area of the hippocampus enables spatial navigation, learning and memory and their firing is tightly controlled by GABAergic interneurons. Both, pyramidal cells and interneurons are highly heterogeneous cell types. Different CA1 pyramidal cells project to distinct brain areas including the subiculum, entorhinal, retrosplenial, prefrontal cortex, olfactory bulb, striatum and/or hypothalamus. Distinct classes of interneurons innervate different subcellular domains of pyramidal cells and operate with different molecular machineries. However, how the different types of pyramidal cells and interneurons contribute to cognitive behaviour remains unknown. In the present proposal we will use novel techniques to test the hypothesis that different types of pyramidal cells and interneurons define spatio-temporal circuitries in the hippocampus of freely-moving rodents underlying cognitive processing. We will test if pyramidal cells projecting to different brain areas make different contribution to spatial information coding, prospective coding for future choices and memory consolidation during sleep. Also, we will determine how identified classes of GABAergic interneurons control pyramidal cell activity and network oscillations during cognitive tasks in freely-moving rats. In addition, we will use transgenic mice in order to up- or down-regulate quickly and reversibly the activity of specific classes of neurons and determine their causal contribution to network operations and cognitive behaviour. Our experiments will determine spatio-temporal codes in and beyond the hippocampal circuit by defining simultaneously the neuronal activity and synaptic connectivity of identified neurons during cognitive behaviours, learning and memory.
Summary
Neuronal activity of pyramidal cells in the CA1 area of the hippocampus enables spatial navigation, learning and memory and their firing is tightly controlled by GABAergic interneurons. Both, pyramidal cells and interneurons are highly heterogeneous cell types. Different CA1 pyramidal cells project to distinct brain areas including the subiculum, entorhinal, retrosplenial, prefrontal cortex, olfactory bulb, striatum and/or hypothalamus. Distinct classes of interneurons innervate different subcellular domains of pyramidal cells and operate with different molecular machineries. However, how the different types of pyramidal cells and interneurons contribute to cognitive behaviour remains unknown. In the present proposal we will use novel techniques to test the hypothesis that different types of pyramidal cells and interneurons define spatio-temporal circuitries in the hippocampus of freely-moving rodents underlying cognitive processing. We will test if pyramidal cells projecting to different brain areas make different contribution to spatial information coding, prospective coding for future choices and memory consolidation during sleep. Also, we will determine how identified classes of GABAergic interneurons control pyramidal cell activity and network oscillations during cognitive tasks in freely-moving rats. In addition, we will use transgenic mice in order to up- or down-regulate quickly and reversibly the activity of specific classes of neurons and determine their causal contribution to network operations and cognitive behaviour. Our experiments will determine spatio-temporal codes in and beyond the hippocampal circuit by defining simultaneously the neuronal activity and synaptic connectivity of identified neurons during cognitive behaviours, learning and memory.
Max ERC Funding
1 760 911 €
Duration
Start date: 2010-01-01, End date: 2014-12-31
Project acronym RIVAL
Project Risk and Valuation of Financial Assets: A Robust Approach
Researcher (PI) Walter Schachermayer
Host Institution (HI) UNIVERSITAT WIEN
Call Details Advanced Grant (AdG), PE1, ERC-2009-AdG
Summary The recent financial crisis has brought to light the importance of correctly evaluating financial assets and their underlying risk. Any such valuation should be robust, i.e., should not be overly sensitive to the modelling assumptions. According to the Black--Scholes theory, which lies at the heart of most current valuation methods, the risk involved by a financial asset can be perfectly eliminated by pursuing a proper dynamic hedging strategy. Unfortunately, although formally elegant, this theory is too much of an idealization of the real world situation. The underlying model fails to be robust in two ways: the prices follow geometric Brownian motion, and transaction costs must be zero. The use of alternative models, e.g. based on fractional Brownian motion, was proposed more than 45 years ago by B.~Mandelbrot. The empirical findings give support to the use of such alternative models. Nevertheless, up to now these models could not be used to value financial assets, as they are not free of arbitrage. We propose an approach which makes it possible to value financial assets in an arbitrage free way, even in the framework of fractal models, by properly taking transaction costs into account. Our approach is based on utility theory. We also propose to control the risk of the related hedging strategies by imposing bounds in terms of risk measures. This allows for more realistic financial modelling with special emphasis on the aspect of the residual risk, remaining after hedging. From a mathematical point of view, our approach is based on the duality theory of infinite-dimensional optimization.
Summary
The recent financial crisis has brought to light the importance of correctly evaluating financial assets and their underlying risk. Any such valuation should be robust, i.e., should not be overly sensitive to the modelling assumptions. According to the Black--Scholes theory, which lies at the heart of most current valuation methods, the risk involved by a financial asset can be perfectly eliminated by pursuing a proper dynamic hedging strategy. Unfortunately, although formally elegant, this theory is too much of an idealization of the real world situation. The underlying model fails to be robust in two ways: the prices follow geometric Brownian motion, and transaction costs must be zero. The use of alternative models, e.g. based on fractional Brownian motion, was proposed more than 45 years ago by B.~Mandelbrot. The empirical findings give support to the use of such alternative models. Nevertheless, up to now these models could not be used to value financial assets, as they are not free of arbitrage. We propose an approach which makes it possible to value financial assets in an arbitrage free way, even in the framework of fractal models, by properly taking transaction costs into account. Our approach is based on utility theory. We also propose to control the risk of the related hedging strategies by imposing bounds in terms of risk measures. This allows for more realistic financial modelling with special emphasis on the aspect of the residual risk, remaining after hedging. From a mathematical point of view, our approach is based on the duality theory of infinite-dimensional optimization.
Max ERC Funding
1 266 000 €
Duration
Start date: 2010-04-01, End date: 2015-03-31
