ERC FUNDED PROJECTS

The project outlined here addresses the fundamental question how the brain encodes and controls behavior. While we have a reasonable understanding of the role of entire brain areas in such processes, and of mechanisms at the molecular and synaptic levels, there is a big gap in our knowledge of how behavior is controlled at the level of defined neuronal circuits. In natural environments, chances for survival depend on learning about possible aversive and appetitive outcomes and on the appropriate behavioral responses. Most studies addressing the underlying mechanisms at the level of neuronal circuits have focused on aversive learning, such as in Pavlovian fear conditioning. Understanding how activity in defined neuronal circuits mediates appetitive learning, as well as how these circuitries are shared and interact with aversive learning circuits, is a central question in the neuroscience of learning and memory and the focus of this grant application. Using a multidisciplinary approach in mice, combining behavioral, in vivo and in vitro electrophysiological, imaging, optogenetic and state-of-the-art viral circuit tracing techniques, we aim at dissecting the neuronal circuitry of appetitive Pavlovian conditioning with a focus on the amygdala, a key brain region important for both aversive and appetitive learning. Ultimately, elucidating these mechanisms at the level of defined neurons and circuits is fundamental not only for an understanding of memory processes in the brain in general, but also to inform a mechanistic approach to psychiatric conditions associated with amygdala dysfunction and dysregulated emotional responses including anxiety and mood disorders.

2 497 200 €

Start date: 2016-01-01, End date: 2020-12-31

Asymmetric cell division is a key mechanism for the generation of cell diversity in eukaryotes. During this process, a polarized mother cell divides into non-equivalent daughters. These may differentially inherit fate determinants, irreparable damages or age determinants. Our aim is to decipher the mechanisms governing the individualization of daughters from each other. In the past ten years, our studies identified several lateral diffusion barriers located in the plasma membrane and the endoplasmic reticulum of budding yeast. These barriers all restrict molecular exchanges between the mother cell and its bud, and thereby compartmentalize the cell already long before its division. They play key roles in the asymmetric segregation of various factors. On one side, they help maintain polarized factors into the bud. Thereby, they reinforce cell polarity and sequester daughter-specific fate determinants into the bud. On the other side they prevent aging factors of the mother from entering the bud. Hence, they play key roles in the rejuvenation of the bud, in the aging of the mother, and in the differentiation of mother and daughter from each other. Recently, we accumulated evidence that some of these barriers are subject to regulation, such as to help modulate the longevity of the mother cell in response to environmental signals. Our data also suggest that barriers help the mother cell keep traces of its life history, thereby contributing to its individuation and adaption to the environment. In this project, we will address the following questions: 1 How are these barriers assembled, functioning, and regulated? 2 What type of differentiation processes are they involved in? 3 Are they conserved in other eukaryotes, and what are their functions outside of budding yeast? These studies will shed light into the principles underlying and linking aging, rejuvenation and differentiation.

2 200 000 €

Start date: 2010-05-01, End date: 2015-04-30

Brain computations rely on proper signal flow through the complex network of connected brain regions. Despite a wealth of anatomical and functional data – from microscopic to macroscopic scale – we still poorly understand the principles of how signal flow is routed through neuronal networks to generate appropriate behavior. Brain dynamics on the 'mesoscopic' scale, the intermediate level where local microcircuits communicate via axonal pathways, has remained a particular blind spot of research as it has been difficult to access under in vivo conditions. Here, I propose to tackle the mesoscopic level of brain dynamics both experimentally and theoretically, adopting a fresh perspective centered on neuronal pathway dynamics. Experimentally, we will utilize and further advance state-of-the-art genetic and optical techniques to create a toolbox for measuring and manipulating signal flow in pathway networks across a broad range of temporal scales. In particular, we will improve fiber-optic based methods for probing the activity of either individual or multiple neuronal pathways with high specificity. Using these tools we will set out to reveal mesoscopic brain dynamics across relevant cortical and subcortical regions in awake, behaving mice. Specifically, we will investigate sensorimotor learning for a reward-based texture discrimination task and rapid sensorimotor control during skilled locomotion. Moreover, by combining fiber-optic methods with two-photon microscopy and fMRI, respectively, we will start linking the meso-level to the micro- and macro-levels. Throughout the project, experiments will be complemented by computational approaches to analyse data, model pathway dynamics, and conceptualize a formal theory of mesoscopic dynamics. This project may transform the field by bridging the hierarchical brain levels and opening significant new avenues to assess physiological as well as pathological signal flow in the brain.

2 498 915 €

Start date: 2016-02-01, End date: 2021-01-31

The frontier in cancer therapy of orchestrating the immune system to attack tumors is producing unprecedented survival benefit in some patients. The corollary is lack of efficacy both in ostensibly responsive tumor types as well as others that are mostly non-responsive. The basis lies in pre-existing and adaptive resistance mechanisms that circumvent induction of tumor-reactive cytotoxic T cells (CTLs) capable of infiltrating solid tumors and eliminating cancer cells. A priori, cancers induced by expression of human papillomavirus oncogenes should be responsive to immunotherapy: these cancers encode immunogenic neo-antigens – the oncoproteins E6/7 – necessary for their manifestation. Rather, such tumors are poorly responsive to immunotherapies. Results from my lab and others using mouse models of HPV-induced cancer have established an actionable hypothesis: during tumorigenesis, such tumors erect multiple barriers to the induction, infiltration, and killing of cancer cells by tumor antigen-reactive CTLs. These include overarching systemic antigen-nonspecific immunosuppression mediated by expanded populations of myeloid cells in spleen and lymph nodes, complemented by immune response-impairing barriers operative in the tumor microenvironment. A spectrum of models will probe these barriers, genetically and pharmacologically, establishing their functional importance, alone and in concert. A major focus will be on how oncogene-expressing keratinocytes elicit a marked expansion of immunosuppressive myeloid cells in spleen and lymph nodes, and how these myeloid cells in turn inhibit development and activation of CD8 T cells and antigen-presenting dendritic cells. Then we’ll assess the therapeutic potential of barrier-breaking strategies combined with immuno-stimulatory modalities. This project will deliver new knowledge about multi-faceted barriers to immunotherapy in these refractory cancers, helping lay the groundwork for efficacious immunotherapy.

2 500 000 €

Start date: 2020-01-01, End date: 2024-12-31