ERC FUNDED PROJECTS

Serotonin (5-HT) is a central neuromodulator and a major target of therapeutic psychoactive drugs, but relatively little is known about how it modulates information processing in neural circuits. The theory of predictive coding postulates that the brain combines raw bottom-up sensory information with top-down information from internal models to make perceptual inferences about the world. We hypothesize, based on preliminary data and prior literature, that a role of 5-HT in this process is to report prediction errors and promote the suppression and weakening of erroneous internal models. We propose that it does this by inhibiting top-down relative to bottom-up cortical information flow. To test this hypothesis, we propose a set of experiments in mice performing olfactory perceptual tasks. Our specific aims are: (1) We will test whether 5-HT neurons encode sensory prediction errors. (2) We will test their causal role in using predictive cues to guide perceptual decisions. (3) We will characterize how 5-HT influences the encoding of sensory information by neuronal populations in the olfactory cortex and identify the underlying circuitry. (4) Finally, we will map the effects of 5-HT across the whole brain and use this information to target further causal manipulations to specific 5-HT projections. We accomplish these aims using state-of-the-art optogenetic, electrophysiological and imaging techniques (including 9.4T small-animal functional magnetic resonance imaging) as well as psychophysical tasks amenable to quantitative analysis and computational theory. Together, these experiments will tackle multiple facets of an important general computational question, bringing to bear an array of cutting-edge technologies to address with unprecedented mechanistic detail how 5-HT impacts neural coding and perceptual decision-making.

2 486 074 €

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

A persistent challenge in unravelling mechanisms that regulate memory function is how to bridge the gap between inter-molecular dynamics of single proteins, activity of individual synapses and emerging properties of neuronal circuits. The prototype condition of disintegrating neuronal circuits is Alzheimer’s Disease (AD). Since the early time of Alois Alzheimer at the turn of the 20th century, scientists have been searching for a molecular entity that is in the roots of the cognitive deficits. Although diverse lines of evidence suggest that the amyloid-beta peptide (Abeta) plays a central role in synaptic dysfunctions of AD, several key questions remain unresolved. First, endogenous Abeta peptides are secreted by neurons throughout life, but their physiological functions are largely unknown. Second, experience-dependent physiological mechanisms that initiate the changes in Abeta composition in sporadic, the most frequent form of AD, are unidentified. And finally, molecular mechanisms that trigger Abeta-induced synaptic failure and memory decline remain elusive. To target these questions, I propose to develop an integrative approach to correlate structure and function at the level of single synapses in hippocampal circuits. State-of-the-art techniques will enable the simultaneous real-time visualization of inter-molecular dynamics within signalling complexes and functional synaptic modifications. Utilizing FRET spectroscopy, high-resolution optical imaging, electrophysiology, molecular biology and biochemistry we will determine the casual relationship between ongoing neuronal activity, temporo-spatial dynamics and molecular composition of Abeta, structural rearrangements within the Abeta signalling complexes and plasticity of single synapses and whole networks. The proposed research will elucidate fundamental principles of neuronal circuits function and identify critical steps that initiate primary synaptic dysfunctions at the very early stages of sporadic AD.

2 000 000 €

Start date: 2011-12-01, End date: 2017-09-30

Elucidating how neural circuits coordinate behaviour, and how molecules underpin the properties of individual neurons are major goals of neuroscience. Optogenetics and neural imaging combined with the powerful genetics and well-described nervous system of C. elegans offer special opportunities to address these questions. Previously, we identified a series of sensory neurons that modulate aggregation of C. elegans. These include neurons that respond to O2, CO2, noxious cues, satiety state, and pheromones. We propose to take our analysis to the next level by dissecting how, in mechanistic molecular terms, these distributed inputs modify the activity of populations of interneurons and motoneurons to coordinate group formation. Our strategy is to develop new, highly parallel approaches to replace the traditional piecemeal analysis. We propose to: 1) Harness next generation sequencing (NGS) to forward genetics, rapidly to identify a molecular ¿parts list¿ for aggregation. Much of the genetics has been done: we have identified almost 200 mutations that inhibit or enhance aggregation but otherwise show no overt phenotype. A pilot study of 50 of these mutations suggests they identify dozens of genes not previously implicated in aggregation. NGS will allow us to molecularly identify these genes in a few months, providing multiple entry points to study molecular and circuitry mechanisms for behaviour. 2) Develop new methods to image the activity of populations of neurons in immobilized and freely moving animals, using genetically encoded indicators such as the calcium sensor cameleon and the voltage indicator mermaid. This will be the first time a complex behaviour has been dissected in this way. We expect to identify novel conserved molecular and circuitry mechanisms.

2 439 996 €

Start date: 2011-04-01, End date: 2017-03-31

"How are actions initiated by the human brain when there is no external sensory cue or other immediate imperative? How do subtle ongoing interactions within the brain and between the brain, body, and sensory context influence the spontaneous initiation of action? How should we approach the problem of trying to identify the neural events that cause spontaneous voluntary action? Much is understood about how the brain decides between competing alternatives, leading to different behavioral responses. But far less is known about how the brain decides ""when"" to perform an action, or ""whether"" to perform an action in the first place, especially in a context where there is no sensory cue to act such as during foraging. This project seeks to open a new chapter in the study of spontaneous voluntary action building on a novel hypothesis recently introduced by the applicant (Schurger et al, PNAS 2012) concerning the role of ongoing neural activity in action initiation. We introduce brain-behavior forecasting, the converse of movement-locked averaging, as an approach to identifying the neurodynamic states that commit the motor system to performing an action ""now"", and will apply it in the context of information foraging. Spontaneous action remains a profound mystery in the brain basis of behavior, in humans and other animals, and is also central to the problem of asynchronous intention-detection in brain-computer interfaces (BCIs). A BCI must not only interpret what the user intends, but also must detect ""when"" the user intends to act, and not respond otherwise. This remains the biggest challenge in the development of high-performance BCIs, whether invasive or non-invasive. This project will take a systematic and collaborative approach to the study of spontaneous self-initiated action, incorporating computational modeling, neuroimaging, and machine learning techniques towards a deeper understanding of voluntary behavior and the robust asynchronous detection of decisions-to-act."

1 338 130 €

Start date: 2015-10-01, End date: 2020-09-30

Converging studies from psychophysics in humans to single-cell recordings in monkeys and rodents indicate that most important cognitive processes depend on both feed-forward and feedback information interacting in the brain. Intriguingly, feedback to early cortical processing stages appears to play a causal role in these processes. Despite the central nature of this fact to understanding brain cognition, there is still no mechanistic explanation as to how this information could be so pivotal and what events take place that might be decisive. In this research program, we will test the hypothesis that the extraordinary performance of the cortex derives from an associative mechanism built into the basic neuronal unit: the pyramidal cell. The hypothesis is based on two important facts: (1) feedback information is conveyed predominantly to layer 1 and (2) the apical tuft dendrites that are the major recipient of this feedback information are highly electrogenic. The research program is divided in to several workpackages to systematically investigate the hypothesis at every level. As a whole, we will investigate the causal link between intrinsic cellular activity and behaviour. To do this we will use eletrophysiological and optical techniques to record and influence cell the intrinsic properties of cells (in particular dendritic activity) in vivo and in vitro in rodents. In vivo experiments will have a specific focus on context driven behaviour and in vitro experiments on the impact of long-range (feedback-carrying) fibers on cell activity. The study will also focus on synaptic plasticity at the interface of feedback information and dendritic electrogenesis, namely synapses on to the tuft dendrite of pyramidal neurons. The proposed program will not only address a long-standing and important hypothesis but also provide a transformational contribution towards understanding the operation of the cerebral cortex.

2 386 304 €

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

In a changing world, one hallmark feature of human behaviour is the ability to learn about the statistics of the environment and use this prior information for action selection. Knowing about a forthcoming event allows for adjusting our actions pre-emptively, which can optimize survival. This proposal studies how the human brain learns about the uncertainty in the environment, and how this leads to flexible and efficient action selection. I hypothesise that the accumulation of evidence for future movements through learning reflects a fundamental organisational principle for action control. This explains widely distributed perceptual-, learning-, decision-, and movement-related signals in the human brain. However, little is known about the concerted interplay between brain regions in terms of effective connectivity which is required for flexible behaviour. My proposal seeks to shed light on this unresolved issue. To this end, I will use i) a multi-disciplinary neuroimaging approach, together with model-based analyses and Bayesian model comparison, adapted to human reaching behaviour as occurring in daily life; and ii) two novel approaches for testing effective connectivity: dynamic causal modelling (DCM) and concurrent transcranial magnetic stimulation-functional magnetic resonance imaging. My prediction is that action selection relies on effective connectivity changes, which are a function of the prior information that the brain has to learn about. If true, this will provide novel insight into the human ability to select actions, based on learning about the uncertainty which is inherent in contextual information. This is relevant for understanding action selection during development and ageing, and for pathologies of action such as Parkinson s disease or stroke.

1 341 805 €

Start date: 2011-06-01, End date: 2016-05-31

AMPA glutamate receptors (AMPAR) play key roles in information processing by the brain as they mediate nearly all fast excitatory synaptic transmission. Their spatio-temporal organization in the post synapse with respect to presynaptic glutamate release sites is a key determinant in synaptic transmission. The activity-dependent regulation of AMPAR organization is at the heart of synaptic plasticity processes underlying learning and memory. Dysfunction of synaptic transmission - hence AMPAR organization - is likely at the origin of a number of brain diseases. Building on discoveries made during my past ERC grant, our new ground-breaking objective is to uncover the mechanisms that link synaptic transmission with the dynamic organization of AMPAR and associated proteins. For this aim, we have assembled a team of neurobiologists, computer scientists and chemists with a track record of collaboration. We will combine physiology, cellular and molecular neurobiology with development of novel quantitative imaging and biomolecular tools to probe the molecular dynamics that regulate synaptic transmission. Live high content 3D SuperResolution Light Imaging (SRLI) combined with electron microscopy will allow unprecedented visualization of AMPAR organization in synapses at the scale of individual subunits up to the level of intact tissue. Simultaneous SRLI and electrophysiology will elucidate the intricate relations between dynamic AMPAR organization, trafficking and synaptic transmission. Novel peptide- and small protein-based probes used as protein-protein interaction reporters and modulators will be developed to image and directly interfere with synapse organization. We will identify new processes that are fundamental to activity dependent modifications of synaptic transmission. We will apply the above findings to understand the causes of early cognitive deficits in models of neurodegenerative disorders and open new avenues of research for innovative therapies.

2 491 157 €

Start date: 2014-02-01, End date: 2019-01-31

Brain and spinal cord diseases affect 38% of the European population and cost over 800 billion € annually; representing by far the largest health challenge. ALS is a prevalent neurological disease caused by motor neuron death with an invariably fatal outcome. I contributed to ALS research with the groundbreaking discovery of TDP-43 mutations, functionally characterized these mutations in the first vertebrate model and demonstrated a genetic interaction with another major ALS gene FUS. Emerging evidence indicates that four major causative factors in ALS, C9orf72, TDP-43, FUS & SQSTM1, genetically interact and could function in common cellular mechanisms. Here, I will develop zebrafish transgenic lines for all four genes, using state of the art genomic editing tools to combine simultaneous gene knockout and expression of the mutant alleles. Using these innovative disease models I will study the functional interactions amongst these four genes and their converging effect on key ALS pathogenic mechanisms: autophagy degradation, stress granule formation and RNA regulation. These studies will permit to pinpoint the molecular cascades that underlie ALS-related neurodegeneration. We will further expand the current ALS network by proposing and validating novel genetic interactors, which will be further screened for disease-causing variants and as pathological markers in patient samples. The power of zebrafish as a vertebrate model amenable to high-content phenotype-based screens will enable discovery of bioactive compounds that are neuroprotective in multiple animal models of disease. This project will increase the fundamental understanding of the relevance of C9orf72, TDP-43, FUS and SQSTM1 by developing animal models to characterize common pathophysiological mechanisms. Furthermore, I will uncover novel genetic, disease-related and pharmacological modifiers to extend the ALS network that will facilitate development of therapeutic strategies for neurodegenerative disorders

2 000 000 €

Start date: 2017-04-01, End date: 2022-03-31

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

Within a 12 month period, 20% of adults will meet criteria for one or more clinical anxiety disorders (ADs). These disorders are hugely disruptive, placing an emotional burden on individuals and their families. While both cognitive behavioural therapy and pharmacological treatment are widely viewed as effective strategies for managing ADs, systematic review of the literature reveals that only 30–45% of patients demonstrate a marked response to treatment (anxiety levels being reduced into the nonaffected range). In addition, a significant proportion of initial responders relapse after treatment is discontinued. There is hence a real and marked need to improve upon current approaches to AD treatment. One possible avenue for improving response rates is through optimizing initial treatment selection. Specifically, it is possible that certain individuals might respond better to cognitive interventions while others might respond better to pharmacological treatment. Recently it has been suggested that there may be two or more distinct biological pathways disrupted in anxiety. If this is the case, then specification of these pathways may be an important step in predicting which individuals are likely to respond to which treatment. Few studies have focused upon this issue and, in particular, upon identifying neural markers that might predict response to cognitive (as opposed to pharmacological) intervention. The proposed research aims to address this. Specifically, it tests the hypothesis that there are at least two mechanisms disrupted in ADs, one entailing amygdala hyper-responsivity to cues that signal threat, the other impoverished recruitment of frontal regions that support cognitive and emotional regulation. Two series of functional magnetic resonance imaging experiments will be conducted. These will investigate differences in amygdala and frontal function during (a) attentional processing and (b) fear conditioning. Initial clinical experiments will investigate whether Generalised Anxiety Disorder and Specific Phobia involve differing degrees of disruption to frontal versus amygdala function during these tasks. This work will feed into training studies, the goal being to characterize AD patient subgroups that benefit from cognitive training.

1 708 407 €

Start date: 2011-04-01, End date: 2016-08-31

Brain consists of two basic cell types – neurons and glia. However, the study of glia in brain function has traditionally been neglected in favor of their more “illustrious” counter-parts – neurons that are classed as the computational units of the brain. Glia have usually been classed as “brain glue” - a supportive matrix on which neurons grow and function. However, recent evidence suggests that glia are more than passive “glue” and actually modulate neuronal function. This has lead to the proposal of a “tripartite synapse”, which recognizes pre- and postsynaptic neuronal elements and glia as a unit. However, what is still lacking is rudimentary information on how these cells actually function in situ. Here we propose taking a “bottom-up” approach, by identifying the molecules (and interactions) that control glial function in situ. This is complicated by the fact that glia show profound changes when placed into culture. To circumvent this, we will use recently developed cell sorting techniques, to rapidly isolate genetically marked glial cells from brain – which can then be analyzed using advanced biochemical and physiological techniques. The long-term aim is to identify proteins that can be “tagged” using transgenic technologies to allow protein function to be studied in real-time in vivo, using sophisticated imaging techniques. Given the number of proteins that may be identified we envisage developing new methods of generating transgenic animals that provide an attractive alternative to current “state-of-the art” technology. The importance of studying glial function is given by the fact that every major brain pathology shows reactive gliosis. In the time it takes to read this abstract, 5 people in the EU will have suffered a stroke – not to mention those who suffer other forms of neurotrauma. Thus, understanding glial function is not only critical to understanding normal brain function, but also for relieving the burden of severe neurological injury and disease

1 490 168 €

Start date: 2012-01-01, End date: 2016-12-31

Despite considerable efforts aimed at prevention and treatment, the prevalence of obesity and type 2 diabetes has increased at an alarming rate worldwide over recent decades. Given the urgent need to develop safe and efficient anti-obesity drugs, the scientific community has to intensify efforts to better understand the mechanisms involved in the pathogenesis of obesity. Based on human genome-wide association studies and targeted mouse mutagenesis models, it has recently emerged that the brain controls most aspects of systemic metabolism and that obesity may be a brain disease. I have recently shown that like neurons, astrocytes also respond to circulating nutrients, and they cooperate with neurons to efficiently regulate energy metabolism. So far, the study of brain circuits controlling energy balance has focused on neurons, ignoring the presence and role of astrocytes. Importantly, our studies were the first to describe that exposure to a high-fat, highsugar (HFHS) diet triggers hypothalamic astrogliosis prior to significant body weight gain, indicating a potentially important role in promoting obesity. Overall, my recent findings suggest a novel model in which astrocytes are actively involved in the central nervous system (CNS) control of metabolism, likely including active crosstalk between astrocytes and neurons. To test this hypothetical model, I propose to develop a functional understanding of astroglia-neuronal communication in the CNS control of metabolism focusing on: 1) dissecting the ability of astrocytes to release gliotransmitters to neurons, 2) assessing how astrocytes respond to neuronal activity, and 3) determining if HFHS-induced astrogliosis interrupts this crosstalk and contributes to the development of obesity and type 2 diabetes. These studies aim to uncover the molecular underpinnings of astrocyte-neuron inputs regulating metabolism in health and disease so as to inspire and enable novel therapeutic strategies to fight diabetes and obesity.

1 499 938 €

Start date: 2018-01-01, End date: 2022-12-31

At every moment in time, the brain receives a vast amount of sensory information about the environment. This makes attention, the process by which we select currently relevant stimuli for processing and ignore irrelevant input, a fundamentally important brain function. Studies in primates have yielded a detailed description of how attention to a stimulus modifies the responses of neuronal ensembles in visual cortex, but how this modulation is produced mechanistically in the circuit is not well understood. Neuronal circuits comprise a large variety of neuron types, and to gain mechanistic insights, and to treat specific diseases of the nervous system, it is crucial to characterize the contribution of different identified cell types to information processing. Inhibition supplied by a small yet highly diverse set of interneurons controls all aspects of cortical function, and the central hypothesis of this proposal is that differential modulation of genetically-defined interneuron types is a key mechanism of attention in visual cortex. To identify the interneuron types underlying attentional modulation and to investigate how this, in turn, affects computations in the circuit we will use an innovative multidisciplinary approach combining genetic targeting in mice with cutting-edge in vivo 2-photon microscopy-based recordings and selective optogenetic manipulation of activity. Importantly, a key set of experiments will test whether the observed neuronal mechanisms are causally involved in attention at the level of behavior, the ultimate readout of the computations we are interested in. The expected results will provide a detailed, mechanistic dissection of the neuronal basis of attention. Beyond attention, selection of different functional states of the same hard-wired circuit by modulatory input is a fundamental, but poorly understood, phenomenon in the brain, and we predict that our insights will elucidate similar mechanisms in other brain areas and functional contexts.

1 466 505 €

Start date: 2014-02-01, End date: 2019-01-31

In the human brain, the 'bottleneck' of neuronal integrity are long axonal projections, which are often the first to degenerate in neuro-psychiatric diseases. We have discovered in mice that oligodendrocytes and Schwann cells are not only essential for the formation of myelin, but also for the functional integrity of axons and their long-term survival. However, the underlying molecular mechanisms have remained obscure. We propose to use experimental mouse genetics to study neuron-glia interactions and to identify axonal signals that control the normal behaviour of myelinating oligodendrocytes. We will then test our hypothesis that axons require oligodendrocytes not only for myelination, but also for the metabolic support of impulse propagation and fast axonal transport. Based on striking pilot observations, we will analyze the mechanisms by which ensheathing glial cells respond to axonal distress and ask in vivo whether they provide glycolysis end products to axonal mitochondria for energy production ('lactate shuttle'). We will also investigate whether myelin lipids are a readily accessible energy store in glia and explore a speculative hypothesis that N-acetyl aspartate is an aspartate-based shuttle of acetyl-CoA residues. If this proposal is successful, we will begin to understand the true function of oligodendrocytes in endogenous neuroprotection and as bystanders of neuronal disease and normal brain aging. This would initiate a paradigm shift for the role of myelinating glial cells, and could open the door for novel therapeutic strategies in a broad range of neurodegenerative diseases, which pose a major burden on the EC health care system.

2 477 800 €

Start date: 2011-04-01, End date: 2016-03-31

Axon growth potential declines during development, contributing to the lack of effective regeneration in the adult central nervous system. What determines the intrinsic growth potential of neurites, and how such growth is regulated during development, disease and following injury is a fundamental question in neuroscience. Although multiple lines of evidence indicate that intrinsic growth capability is genetically encoded, its nature remains poorly defined. Neuronal remodeling of the Drosophila mushroom body offers a unique opportunity to study the mechanisms of various types of axon degeneration and growth. We have recently demonstrated that regrowth of axons following developmental pruning is not only distinct from initial outgrowth but also shares molecular similarities with regeneration following injury. In this proposal we combine state of the art tools from genomics, functional genetics and microscopy to perform a comprehensive study of the mechanisms underlying axon growth during development and following injury. First, we will combine genetic, biochemical and genomic studies to gain a mechanistic understanding of the developmental regrowth program. Next, we will perform extensive transcriptomic analyses and comparisons aimed at defining the genetic programs involved in initial axon growth, developmental regrowth, and regeneration following injury. Finally, we will harness the genetic power of Drosophila to perform a comprehensive functional analysis of genes and pathways, those previously known and new ones that we will discover, in various neurite growth paradigms. Importantly, these functional assays will be performed in the same organism, allowing us to use identical genetic mutations across our analyses. To this end, our identification of a new genetic program regulating developmental axon regrowth, together with emerging tools in genomics, places us in a unique position to gain a broad understanding of axon growth during development and following injury.

2 000 000 €

Start date: 2014-03-01, End date: 2019-02-28

Learning and memory are the basis of our behaviour and mental well-being. Understanding the mechanisms of structural and cellular plasticity in defined neuronal circuits in vivo will be crucial to elucidate principles of circuit-specific memory formation and their relation to changes in neuronal ensemble dynamics. Structural plasticity studies were technically limited to cortex, excluding deep brain areas like the amygdala, and mainly focussed on the input site (dendritic spines), whilst the plasticity of the axon initial segment (AIS), a neuron’s site of output generation, was so far not studied in vivo. Length and location of the AIS are plastic and strongly affects a neurons spike output. However, it remains unknown if AIS plasticity regulates neuronal activity upon learning in vivo. We will combine viral expression of AIS live markers and genetically-encoded Ca2+-sensors with novel deep brain imaging techniques via gradient index (GRIN) lenses to investigate how AIS location and length are regulated upon associative learning in amygdala circuits in vivo. Two-photon time-lapse imaging of the AIS of amygdala neurons upon fear conditioning will help us to track learning-driven AIS location dynamics. Next, we will combine miniature microscope imaging of neuronal activity in freely moving animals with two-photon imaging to link AIS location, length and plasticity to the intrinsic activity as well as learning-related response plasticity of amygdala neurons during fear learning and extinction in vivo. Finally, we will test if AIS plasticity is a general cellular plasticity mechanisms in brain areas afferent to the amygdala, e.g. thalamus. Using a combination of two-photon and miniature microscopy imaging to map structural dynamics of defined neural circuits in the amygdala and its thalamic input areas will provide fundamental insights into the cellular mechanisms underlying sensory processing upon learning and relate network level plasticity with the cellular level.

1 475 475 €

Start date: 2018-12-01, End date: 2023-11-30

We are largely unaware of our own motives. Understanding our motives can be reduced to knowing how we form goals and these goals translate into behavior. Goals can be defined as pleasurable situations that we particularly value and that we intend to reach. Recent investigation in the emerging field of neuro-economics has put forward a neuronal network constituting a brain valuation system (BVS). We wish to build a more comprehensive account of motivational processes, investigating not only valuation and choice but also effort (how much energy we would spend to attain a goal). More specifically, our aims are to better describe 1) how the brain assigns values to various objects and actions, 2) how values depend on parameters such as reward magnitude, probability, delay and cost, 3) how values are affected by social contexts, 4) how values are modified through learning and 5) how values influence the brain systems (perceptual, cognitive and motor) that underpin behavioral performance. To these aims, we would combine three approaches: 1) human cognitive neuroscience, which is central as we ultimately wish to understand ourselves, as well as human pathological conditions where motivation is either deficient (apathy) or out of control (compulsion), 2) primate neurophysiology, which is essential to describe information processing at the single-unit level and to derive causality by observing behavioral consequences of brain manipulations, 3) computational modeling, which is mandatory to link quantitatively the different descriptions levels (single-unit recordings, local field potentials, regional BOLD signal, vegetative manifestations and motor outputs). A bayesian framework will be developed to infer from experimental measures the subjects prior beliefs and value functions. We believe that our team, bringing together three complementary perspectives on motivation within a clinical environment, would represent a unique education and research center in Europe.

1 346 000 €

Start date: 2011-03-01, End date: 2016-08-31

Humans interact with other people throughout their lives. This project aims to demonstrate that the complex social shaping of the human brain can be adequately tackled only by taking a leap from the conven-tional single-person neuroscience to two-person neuroscience. We will (1) develop a conceptual framework and experimental setups for two-person neuroscience, (2) apply time-sensitive methods for studies of two interacting persons, monitoring both brain and autonomic nervous activity to also cover the brain body connection, (3) use gaze as an index of subject s attention to simplify signal analysis in natural environments, and (4) apply insights from two-person neuroscience into disorders of social interaction. Brain activity will be recorded with millisecond-accurate whole-scalp (306-channel) magnetoencepha-lography (MEG), associated with EEG, and with the millimeter-accurate 3-tesla functional magnetic reso-nance imaging (fMRI). Heart rate, respiration, galvanic skin response, and pupil diameter inform about body function. A new psychophysiological interaction setting will be built, comprising a two-person eye-tracking system. Novel analysis methods will be developed to follow the interaction and possible synchronization of the two persons signals. This uncoventional approach crosses borders of neuroscience, social psychology, psychophysiology, psychiatry, medical imaging, and signal analysis, with intriguing connections to old philosophical questions, such as intersubjectivity and emphatic attunement. The results could open an unprecedented window into human human, instead of just brain brain, interactions, helping to understand also social disorders, such as autism and schizophrenia. Further applications include master apprentice and patient therapist relationships. Advancing from studies of single persons towards two-person neuroscience shows promise of a break-through in understanding the dynamic social shaping of human brain and mind.

2 489 643 €

Start date: 2009-01-01, End date: 2014-12-31

We and others have recently delineated the molecular architecture of a new feedback pathway in brain synapses, which operates as a synaptic circuit breaker. This pathway is supposed to use a group of lipid messengers as retrograde synaptic signals, the so-called endocannabinoids. Although heterogeneous in their chemical structures, these molecules along with the psychoactive compound in cannabis are thought to target the same effector in the brain, the CB1 receptor. However, the molecular catalog of these bioactive lipids and their metabolic enzymes has been expanding rapidly by recent advances in lipidomics and proteomics raising the possibility that these lipids may also serve novel, yet unidentified physiological functions. Thus, the overall aim of our research program is to define the molecular and anatomical organization of these endocannabinoid-mediated pathways and to determine their functional significance. In the present proposal, we will focus on understanding how these novel pathways regulate synaptic and extrasynaptic signaling in hippocampal neurons. Using combination of lipidomic, genetic and high-resolution anatomical approaches, we will identify distinct chemical species of endocannabinoids and will show how their metabolic enzymes are segregated into different subcellular compartments in cell type- and synapse-specific manner. Subsequently, we will use genetically encoded gain-of-function, loss-of-function and reporter constructs in imaging experiments and electrophysiological recordings to gain insights into the diverse tasks that these new pathways serve in synaptic transmission and extrasynaptic signal processing. Our proposed experiments will reveal fundamental principles of intercellular and intracellular endocannabinoid signaling in the brain.

1 638 000 €

Start date: 2009-11-01, End date: 2014-10-31

The brain is composed of a set of areas specialized in specific computations whose outputs need to be transferred to other specialized areas for cognition to emerge. To account for context-dependent behaviors, the information has to be flexibly routed through the fixed anatomy of the brain. The aim of my proposal is to test a general framework for flexible communication between brain areas based on nested oscillations which I recently developed. The general idea is that internally-driven slow oscillations (<20Hz) either set-up or prevent the communication between brain areas. Stimulus-driven gamma oscillations (>30Hz), nested in the slow oscillations, can then be directed to task-relevant areas of the network. I plan to use a multimodal, multi-scale and transversal (human and monkey) approach in experiments manipulating visual processing, attention and memory to test core predictions of my framework. The theoretical approach and the methodological development used in my project will provide the basis for future fundamental and clinical research.

1 333 718 €

Start date: 2017-02-01, End date: 2022-01-31

The core function of all brains is to compute the current state of the world, compare it to the desired state of the world and select motor programs that drive behavior minimizing any mismatch. The circuits underlying these functions are the key to understand brains in general, but so far they are completely unknown. Three problems have hindered progress: 1) The animal’s desired state of the world is rarely known. 2) Most studies in simple models have focused on sensory driven, reflex-like processes, and not considered self-initiated behavior. 3) The circuits underlying complex behaviors in vertebrates are widely distributed, containing millions of neurons. With this proposal I aim at overcoming these problems using insects, whose tiny brains solve the same basic problems as our brains but with 100,000 times fewer cells. Moreover, the central complex, a single conserved brain region consisting of only a few thousand neurons, is crucial for sensory integration, motor control and state-dependent modulation, essentially being a ‘brain in the brain’. To simplify the problem further I will focus on navigation behavior. Here, the desired and actual states of the world are equal to the desired and current headings of the animal, with mismatches resulting in compensatory steering. I have previously shown how the central complex encodes the animal’s current heading. Now I will use behavioral training to generate animals with highly defined desired headings, and correlate neural activity with the animal’s ‘intentions’ and actions - at the level of identified neurons. To establish the involved conserved core circuitry valid across insects I will compare species with distinct lifestyles. Secondly, I will reveal how these circuits have evolved to account for each species’ unique ecology. The proposed work will provide a coherent framework to study key concepts of fundamental brain functions in unprecedented detail - using a single, conserved, but flexible neural circuit.

1 500 000 €

Start date: 2017-01-01, End date: 2021-12-31

Aggregates of proteins such as amyloid-beta and alpha-synuclein circulate the extracellular space of the brain (ECS) and are thought to be key players in the development of neurodegenerative diseases. The clearance of these aggregates (among other toxic metabolites) is a fundamental physiological feature of the brain which is poorly understood due to the lack of techniques to study the nanoscale organisation of the ECS. Exciting advances in this field have recently shown that clearance is enhanced during sleep due to a major volume change in the ECS, facilitating the flow of the interstitial fluid. However, this process has only been characterised at a low spatial resolution while the physiological changes occur at the nanoscale. The recently proposed “glymphatic” pathway still remains controversial, as there are no techniques capable of distinguishing between diffusion and bulk flow in the ECS of living animals. Understanding these processes at a higher spatial resolution requires the development of single-molecule imaging techniques that can study the brain in living animals. Taking advantage of the strategies I have recently developed to target single-molecules in the brain in vivo with nanoparticles, we will do “nanoscopy” in living animals. Our proposal will test the glymphatic pathway at the spatial scale in which events happen, and explore how sleep and wake cycles alter the ECS and the diffusion of receptors in neuronal plasma membrane. Overall, BrainNanoFlow aims to understand how nanoscale changes in the ECS facilitate clearance of protein aggregates. We will also provide new insights to the pathological consequences of impaired clearance, focusing on the interactions between these aggregates and their putative receptors. Being able to perform single-molecule studies in vivo in the brain will be a major breakthrough in neurobiology, making possible the study of physiological and pathological processes that cannot be studied in simpler brain preparations.

1 552 948 €

Start date: 2018-12-01, End date: 2023-11-30

We are currently witnessing a paradigm shift in our understanding of human brain function, moving towards a clearer description of cortical processing. Sensory systems are no longer considered as 'passively recording' but rather as dynamically anticipating and adapting to the rapidly changing environment. These new ideas are encompassed in the predictive coding framework, and indeed in a unifying theory of the brain (Friston, 2010). In terms of brain computation, a predictive model is created in higher cortical areas and communicated to lower sensory areas through feedback connections. Based on my pioneering research I propose experiments that are capable of ‘brain-reading’ cortical feedback– which would contribute invaluable data to theoretical frameworks. The proposed research project will advance our understanding of ongoing brain activity, contextual processing, and cortical feedback - contributing to what is known about general cortical functions. By providing new insights as to the information content of cortical feedback, the proposal will fill one of the most important gaps in today’s knowledge about brain function. Friston’s unifying theory of the brain (Friston, 2010) and contemporary models of the predictive-coding framework (Hawkins and Blakeslee, 2004;Mumford, 1992;Rao and Ballard, 1999) assign feedback processing an essential role in cortical processing. Compared to feedforward information processing, our knowledge about feedback processing is in its infancy. The proposal introduces parametric and explorative brain reading designs to investigate this feedback processing. The chief goal of my proposal will be precision measures of cortical feedback, and a more ambitious objective is to read mental images and inner thoughts.

1 494 714 €

Start date: 2012-12-01, End date: 2017-11-30

Our ability to think, to memorize and focus our thoughts depends on acetylcholine signaling in the brain. The loss of cholinergic signalling in for instance Alzheimer’s disease strongly compromises these cognitive abilities. The traditional view on the role of cholinergic input to the neocortex is that slowly changing levels of extracellular acetylcholine (ACh) mediate different arousal states. This view has been challenged by recent studies demonstrating that rapid phasic changes in ACh levels at the scale of seconds are correlated with focus of attention, suggesting that these signals may mediate defined cognitive operations. Despite a wealth of anatomical data on the organization of the cholinergic system, very little understanding exists on its functional organization. How the relatively sparse input of cholinergic transmission in the prefrontal cortex elicits such a profound and specific control over attention is unknown. The main objective of this proposal is to develop a causal understanding of how cellular mechanisms of fast acetylcholine signalling are orchestrated during cognitive behaviour. In a series of studies, I have identified several synaptic and cellular mechanisms by which the cholinergic system can alter neuronal circuitry function, both in cortical and subcortical areas. I have used a combination of behavioral, physiological and genetic methods in which I manipulated cholinergic receptor functionality in prefrontal cortex in a subunit specific manner and found that ACh receptors in the prefrontal cortex control attention performance. Recent advances in optogenetic and electrochemical methods now allow to rapidly manipulate and measure acetylcholine levels in freely moving, behaving animals. Using these techniques, I aim to uncover which cholinergic neurons are involved in fast cholinergic signaling during cognition and uncover the underlying neuronal mechanisms that alter prefrontal cortical network function.

1 499 242 €

Start date: 2011-11-01, End date: 2016-10-31

The brain is an extraordinary complex assembly of neuronal and glial cells that underpins cognitive functions. How adequate numbers of these cells are generated by neural stem cells in embryonic and early postnatal development and how they distribute and interconnect within brain tissue is still debated. In particular, the potentialities of individual neural stem cells, their potential heterogeneity and the mechanisms regulating their function are still poorly characterized in situ; likewise, the clonal architecture of mature brain tissue and its influence on neural circuitry are only partially explored. Deciphering these aspects is essential to link neural circuit development, structure and function, and to understand the aetiology of neurodevelopmental disorders. We have recently established transgenic strategies to simultaneously track the lineage of multiple individual neural stem cells in the intact developing brain and experimentally perturb their development. We will use these approaches in combination with recent large-volume imaging methods for high-throughput analysis of individual neural and glial clones in the mouse cortex. This will allow us to assay neural progenitor potentialities and equivalence, characterize developmental changes occurring in the neurogenic niche, describe the clonal organization of the mature cortex and study its link with neural connectivity. To decipher intrinsic and extrinsic mechanisms regulating neural progenitor activity and understand how they produce appropriate numbers of cells, we will assay the outcome of functional perturbations targeting key steps of neural development, introduced in precursors or in their local environment. These experiments will reveal how neural stem cell output might be regulated by cell interactions and intercellular signals. This multidisciplinary project will set the basis for quantitative analysis of brain development with single-cell resolution in normal and pathological conditions.

1 929 713 €

Start date: 2015-07-01, End date: 2021-06-30

Synaptic scaffolding molecules control the localization and the abundance of neurotransmitter receptors at the synapse, a key parameter to shape synaptic transfer function. Most characterized synaptic scaffolds are intracellular, yet a growing number of secreted proteins appear to organize the synapse from the outside of the cell. We recently demonstrated in C. elegans that an evolutionarily conserved protein secreted by motoneurons specifies the excitatory versus inhibitory identity of the postsynaptic domains at neuromuscular synapses. We propose to use this system as a genetically tractable paradigm to perform a comprehensive characterization of this unforeseen synaptic organization. Specifically, this project will pursue 4 complementary aims: 1) Identify and characterize a comprehensive set of genes that organize and control the formation and maintenance of these scaffolds through a series of genetic screens based on the direct visualization of fluorescent acetylcholine and GABA receptors in living animals. 2) Solve the spatial synaptic organization of these scaffolds at a nanoscale resolution using super-resolutive and correlative light and electron microscopy, and analyze their dynamic behavior in vivo by implementing Single Particle Tracking imaging in living worms. 3) Decipher the role of the synaptomatrix in the organization of synaptic extracellular scaffolds and evaluate its functional contribution at the physiological and molecular levels using a candidate gene strategy and innovative imaging. 4) Analyze the formation and decline of these scaffolds at the lifetime scale and evaluate the role of synaptic activity and aging in these processes by taking advantage of the possibility to follow identified synapses over the entire life of C. elegans. Using powerful genetics in combination with cutting-edge in vivo imaging and electrophysiology, we anticipate to identify new genes and new mechanisms at work to regulate normal and pathological synaptic function.

2 492 750 €

Start date: 2016-10-01, End date: 2022-09-30

An expanded GGGGCC repeat in a non-coding region of the C9orf72 gene is the most common known cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). The repeat RNA is transcribed and accumulates in neuronal RNA aggregates, implicating RNA toxicity as a key pathogenic mechanism. However, the pathways that lead to neurodegeneration are unknown. My lab has made pioneering contributions to the understanding of C9orf72 FTD/ALS, and reported the first structure of the repeat RNA, and the first description of both sense and antisense RNA aggregates in patient brain. We have now developed new disease models that allow, for the first time, the dissection of RNA toxicity both in vivo and in sophisticated neuronal culture models. We have also used our knowledge of the repeat structure to identify novel small molecules that show very strong binding to the repeats. We will utilise our innovative disease models in a multidisciplinary approach to fully dissect the cellular pathways underlying C9orf72 repeat RNA toxicity in vivo, on a genome-wide scale. Altered RNA metabolism has been implicated in a wide range of neurodegenerative diseases, indicating that our findings will provide profound new insight into fundamental mechanisms of neuronal maintenance and survival. This research programme will also deliver a step change in our understanding of C9orf72 FTD/ALS pathogenesis and provide essential insight for the identification of small molecules with genuine therapeutic potential. RNA-mediated mechanisms are now known to be a common theme in neurodegeneration, suggesting these findings will have broad significance.

1 985 699 €

Start date: 2015-10-01, End date: 2021-03-31

Blindness affects millions of people worldwide and has devastating consequences for those affected. It is often caused by a loss of photoreceptors in the retina, whose residual cellular network remains largely unaffected. Various strategies have been chosen to restore vision, such as electrical stimulation with retinal implants. More recently, natural photoreceptor proteins and stem cells have been explored. We propose a radically different ¿photopharmacological¿ approach toward vision restoration that is based on synthetic photoswitches. These are combined in various ways with natural receptor proteins to create hybrid photoreceptors, which can then sensitize neurons toward light. In a way we are ¿teaching old receptors new tricks¿ and let them carry out functions that they have not evolved for in Nature. Our hybrid photoreceptors and photochromic drugs work well in experimental animals and have already been shown to influence their visual behavior. To make these molecules work in humans, we need to improve their photophysical properties and investigate their delivery, stability and pharmacology. This requires an extensive program in synthetic chemistry, which should be accompanied by effective and immediate neurobiological evaluation. Our very general approach to optically controlling neural activity can be applied to other functions and malfunctions of the nervous system, such as pain or epilepsy, but its greatest medical potential currently lies in the restoration of vision.

2 484 613 €

Start date: 2011-05-01, End date: 2016-04-30

A critical question in neuroscience is to understand how neurons wire up to form a functional network. During the wiring of the brain it is important to establish mechanisms that act as safeguards to control and stabilize neuronal excitability in the face of large, chronic changes in neuronal or network activity. This is especially true for developing systems that undergo rapid and large scale forms of plasticity, which could easily lead to large imbalances in activity. If left unchecked, they could lead the network to its extremes: a complete loss of signal or epileptic-like activity. For this reason neurons employ different strategies to maintain their excitability within reasonable bounds. This proposal will focus on two crucial sites for neuronal information processing and integration: the synapse and the axon initial segment (AIS). Both sites undergo important structural and functional rearrangements in response to chronic activity changes, thus controlling the input-output function of a neuron and allowing the network to function efficiently. This proposal will explore novel forms of plasticity that occur during development and which are key to establishing a functional network. They range from understanding the role of activity during synapse formation to how pre- and postsynaptic structure and function become matched during development. Finally, it tackles a novel form of plasticity that lies downstream of synaptic inputs and is responsible for setting the threshold of action potential firing: the axon initial segment. Here, chronic changes in network activity results in a physical relocation of the AIS along the axon, which in turn alters the excitability of the neuron. This proposal will focus on the central issue of how a neuron alters both its input (synapses) and output (AIS) during development to maintain its activity levels within a set range and allow a functional network to form.

1 500 000 €

Start date: 2012-03-01, End date: 2017-02-28

The mammalian brain is assembled from thousands of neuronal cell types that are organized into distinct circuits to perform behaviourally relevant computations. To gain mechanistic insights about brain function and to treat specific diseases of the nervous system it is crucial to understand what these local circuits are computing and how they achieve these computations. By examining the structure and function of a few genetically identified and experimentally accessible neural circuits we plan to address fundamental questions about the functional architecture of neural circuits. First, are cell types assigned to a unique functional circuit with a well-defined function or do they participate in multiple circuits (“multitasking cell types”), adjusting their role depending on the state of these circuits? Second, does a neural circuit perform “a single computation” or depending on the information content of its inputs can it carry out radically different functions? Third, how, among the large number of other cell types, do the cells belonging to the same functional circuit connect together during development? We use the mouse retina as a model system to address these questions. Finally, we will study the structure and function of a specialised neural circuit in the human fovea that enables humans to read. We predict that our insights into the mechanism of multitasking, network switches and the development of selective connectivity will be instructive to study similar phenomena in other brain circuits. Knowledge of the structure and function of the human fovea will open up new opportunities to correlate human retinal function with human visual behaviour and our genetic technologies to study human foveal function will allow us and others to design better strategies for restoring vision for the blind.

1 499 000 €

Start date: 2010-11-01, End date: 2015-10-31

Each year millions of animals undertake remarkable migratory journeys, across oceans and through hemispheres, guided by the Earth’s magnetic field. The cellular and molecular basis of this enigmatic sense, known as magnetoreception, remains an unsolved scientific mystery. One hypothesis that attempts to explain the basis of this sensory faculty is known as the magnetite theory of magnetoreception. It argues that magnetic information is transduced into a neuronal impulse by employing the iron oxide magnetite (Fe3O4). Current evidence indicates that pigeons employ a magnetoreceptor that is associated with the ophthalmic branch of the trigeminal nerve and the vestibular system, but the sensory cells remain undiscovered. The goal of this ambitious proposal is to discover the cells and molecules that mediate magnetoreception. This overall objective can be divided into three specific aims: (1) the identification of putative magnetoreceptive cells (PMCs); (2) the cellular characterisation of PMCs; and (3) the discovery and functional ablation of molecules specific to PMCs. In tackling these three aims this proposal adopts a reductionist mindset, employing and developing the latest imaging, subcellular, and molecular technologies.

1 499 752 €

Start date: 2014-04-01, End date: 2019-03-31

Humans are endowed with a number of advanced cognitive abilities not seen in other species. So what allows the human brain to stand out from the rest in these capabilities? In general, the brains of primates, including humans, have more neurons per unit volume than other mammals. But humans are also in the fortunate position of having the largest of the primate brains, making the number of neurons in the human cerebral cortex greatly expanded. Thus, the difference seems to be a matter of quantity, not quality. My laboratory is interested in understanding how neuron number, and thus brain size, is determined in human brain development. The research proposed here is aimed at taking an evolutionary approach to this question and comparing brain development in an in vitro 3D model system, cerebral organoids. This method, which relies on self-organization from differentiating pluripotent stem cells, recapitulates remarkably well the endogenous developmental program of the human brain. Having previously established the brain organoid approach, and more recently improved upon it with the application of bioengineering, my laboratory is in a unique position to carry out functional studies of human brain development. I propose to use this approach to compare developing human brain tissue to that of other hominid species and tease apart unique features of human neural stem cells and progenitors that allow them to generate more neurons and therefore a greater cerebral cortical size. Furthermore, we will perform transcriptomic and functional screening to identify factors underlying this expansion, followed by careful genetic substitution to test the contributions of putative evolutionary changes. In this way, we will functionally test putative human evolutionary changes in a manner not previously possible.

1 444 911 €

Start date: 2018-07-01, End date: 2023-06-30

This research proposal’s goal is to investigate the role of cortico-hippocampal interactions during the encoding and consolidation of a memory. Current memory consolidation models postulate that memory storage in our brains occurs by a dynamic process- a recent episodic experience is initially encoded in the hippocampus, and during off-line states such as sleep, the encoded memory is gradually transferred to neocortex for long-term storage. One potential neural mechanism by which this could occur is replay, a phenomenon where neural activity patterns in the hippocampus evoked by a previous experience reactivate spontaneously during non-REM sleep, leading to coordinated cortical reactivation. While previous work suggests that hippocampal replay is important for encoding new memories, how memory consolidation is accomplished through cortico-hippocampal interactions is not well understood. This research project has three major aims- 1) examine how cortical feedback influences which spatial trajectory is replayed by the hippocampus, 2) investigate how the hippocampal replay of a behavioural episode modifies cortical circuits, 3) measure the causal role of cortico-hippocampal interactions in consolidating memories. We will record ensemble activity from freely moving rats during an auditory-spatial association task and during post-behavioural sleep sessions. We will focus our ensemble recordings on two brain regions: 1) the dorsal CA1 region of the hippocampus, where the phenomenon of sleep replay has been most extensively examined, and 2) auditory cortex, a region of the brain critical for both auditory perception and long-term memory storage. This work will use behavioral and molecular-genetic techniques in combination with large-scale electrophysiological recordings, to help elucidate the role of cortico-hippocampal interactions in memory encoding and consolidation.

1 500 000 €

Start date: 2015-04-01, End date: 2021-03-31

"Communication between the nervous and the immune system is pivotal for maintaining homeostasis and ensuring rapid and efficient reaction to stress and infection insults. The emergence of microRNAs (miRs) as regulators of gene expression and of acetylcholine (ACh) signalling as regulator of anxiety and inflammation provides a model for studying this interaction. My hypothesis is that 1) a specific sub-group of miRs, designated ""CholinomiRs"", may silence multiple target genes in the neuro-immune interface; 2) these miRs compete with each other on the interaction with their targets, and 3) mutations interfering with miR binding lead to inherited susceptibility to anxiety and inflammation disorders by modifying these interactions. Our preliminary findings have shown that by targeting acetylcholinesterase (AChE), CholinomiR-132 can intensify acute stress, resolve intestinal inflammation and change post-ischemic stroke responses. Further, we have identified clustered single nucleotide polymorphisms (SNPs) interfering with AChE silencing by several miRs which associate with elevated trait anxiety, blood pressure and inflammation. To further study miR regulators of ACh signalling, I plan to: (1) Identify anxiety and inflammation-induced changes in CholinomiRs and their targets in challenged brain and immune cells. (2) Establish the roles of these targets for one selected CholinomiR by tissue-specific manipulations. (3) Study primate-specific CholinomiRs by continued human DNA screens to identify SNPs and in ""humanized"" mice with knocked-in human AChE and transgenic CholinomiR-608. (4) Test if therapeutic modulation of aberrant CholinomiR expression can restore homeostasis. This research will clarify how miRs interact with each other in health and disease, introduce the dimension of complexity of multi-target competition and miR interactions and make a conceptual change in miRs research while enhancing the ability to intervene with diseases involving impaired ACh signalling."

2 375 600 €

Start date: 2013-03-01, End date: 2018-02-28

The key organizing principles that characterize neuronal systems include asymmetric, parallel, and topographic connectivity of the neural circuits. The main aim of my research is to elucidate the key principles underlying functional development of neural circuits by focusing on those organizing principles. I choose mouse visual system as my model since it contains all of these principles and provides sophisticated genetic tools to label and manipulate individual circuit components. My research is based on the central hypothesis that the mechanisms of brain development cannot be fully understood without first identifying individual functional cell types in adults, and then understanding how the functions of these cell types become established, using cell-type-specific molecular and synaptic mechanisms in developing animals. Recently, I have identified several transgenic mouse lines in which specific cell types in a visual center, the superior colliculus, are labeled with Cre recombinase in both developing and adult animals. Here I will take advantage of these mouse lines to ask fundamental questions about the functional development of neural circuits. First, how are distinct sensory features processed by the parallel topographic neuronal pathways, and how do they contribute to behavior? Second, what are the molecular and synaptic mechanisms that underlie developmental circuit plasticity for forming parallel topographic neuronal maps in the brain? Third, what are the molecular mechanisms that set up spatially asymmetric circuit connectivity without the need for sensory experience? I predict that my insights into the developmental mechanism of asymmetric, parallel, and topographic connectivity and circuit plasticity will be instructive when studying other brain circuits which contain similar organizing principles.

1 500 000 €

Start date: 2015-04-01, End date: 2020-03-31

How does the brain integrate inputs from the environment to generate perception and drive decisions? An enigmatic brain region called the claustrum has been suggested to play a role by integrating inputs from multiple brain regions. There is strong interconnectivity between claustrum and nearly every neocortical brain region, indicating that it exerts widespread influence on brain function. However, approaches to specifically record from or manipulate activity in the claustrum have been hindered by the inability to target it selectively. This has been difficult due to the anatomy of the claustrum: it is a long, thin bilateral nucleus buried between the neocortex and the striatum. This proposal aims to understand the role of the claustrum in multisensory integration and behaviour by developing new approaches for monitoring and manipulating the activity of the claustrum. We will harness recent advances in electrophysiological, genetic, optical, and behavioural tools to probe its connectivity, activity, and function in a precise manner. Understanding the role of the claustrum in brain function will provide fundamental insight into information processing in the neocortex, which is a major goal in neuroscience. The claustrum is unique because of its dense reciprocal connectivity with neocortex but nearly complete lack of direct subcortical sensory input. This particular anatomical structure indicates the possibility of a unique function, but none has been observed yet. This proposal will rectify the paucity of data on this distinctive structure by applying a battery of modern tools to address the function of the claustrum. Experiments will address the following key questions: 1. How are claustrocortical inputs integrated and what is the effect of corticoclaustral feedback? 2. What is the activity of claustral neurons during sensory stimulation and motor output? 3. What are the causal relationships between claustrum activity and animal behaviour?

1 500 000 €

Start date: 2019-10-01, End date: 2024-09-30

In this project, the basal ganglia are defined as actor-critic reinforcement learning networks that aim at an optimal tradeoff between the maximization of future cumulative rewards and the minimization of the cost (the reinforcement driven multi objective optimization RDMOO model). This computational model will be tested by multiple neuron recordings in the major basal ganglia structures of monkeys engaged in a similar behavioral task. We will further validate the RMDOO computational model of the basal ganglia by extending our previous studies of neural activity in the MPTP primate model of Parkinson's disease to a primate model of central serotonin depletion and emotional dysregulation disorders. The findings in the primate model of emotional dysregulation will then be compared to electrophysiological recordings carried out in human patients with treatment-resistant major depression and obsessive compulsive disorder during deep brain stimulation (DBS) procedures. I aim to find neural signatures (e.g., synchronous gamma oscillations in the actor part of the basal ganglia as predicted by the RMDOO model) characterizing these emotional disorders and to use them as triggers for closed loop adaptive DBS. Our working hypothesis holds that, as for the MPTP model of Parkinson's disease, closed loop DBS will lead to greater amelioration of the emotional deficits in serotonin depleted monkeys. This project incorporates extensive collaborations with a team of neurosurgeons, neurologists, psychiatrists, and computer science/ neural network researchers. If successful, the findings will provide a firm understanding of the computational physiology of the basal ganglia networks and their disorders. Importantly, they will pave the way to better treatment of human patients with severe mental disorders.

2 476 922 €

Start date: 2013-12-01, End date: 2018-11-30

How does the brain integrate diverse sensory inputs and generate appropriate motor commands? Our cerebellum is a key region for such a sensorimotor processing, empowered by its sophisticated neural computation and constant communication with other brain regions. The well-timed cerebellar information is integrated and funneled to other brain regions through the cerebellar nuclei (CN). Yet, how CN circuitry contributes to the cerebellar control of sensorimotor processing is unclear. My recent work indicates that the CN activity serves various functions ranging from the online motor control, the amplitude amplification of cerebellar outputs to the control of motor planning. Given these advances, I am now in a unique position to decipher the properties of CN neurons and identify their specific roles in different forms of sensorimotor processing. It is my central hypothesis that depending on the specific demands of the task, CN neurons can either facilitate or suppress the activity of downstream regions with millisecond precision; and the anatomical, genetic and functional properties of CN neurons are tailored to the particular task involved. To test this hypothesis, I will 1) identify the activity patterns of different CN modules during the acquisition and execution of two sensorimotor tasks and characterize the relevant extra-cerebellar inputs to these modules; 2) identify the connectivity-transcription logic of different CN modules and link them to their task-specific outputs; and 3) examine the impacts of manipulating anatomically and/or genetically defined CN neurons on the downstream regions during different sensorimotor tasks. I will accomplish these key objectives by developing various novel electrophysiological, optogenetic, molecular and imaging techniques. My research is likely to break new ground, demonstrating that the identity of CN neurons is determined by their differential temporal demands of sensorimotor tasks controlled by different brain structures.

1 400 000 €

Start date: 2019-11-01, End date: 2024-10-31

A key question in neuroscience is how information is processed by sensory systems to guide behavior. Most of our knowledge about sensory processing is based on presentation of simple isolated stimuli and recording corresponding neural activity in relevant brain areas. Yet sensory stimuli in real life are never isolated and typically not simple. How the brain processes complex stimuli, simultaneously arising from multiple objects is unknown. Our daily experience (as well as well-controlled experiments) shows that only parts of a complex sensory scene can be perceived - we cannot listen to more than one speaker in a party. Importantly, one can easily choose what is important and should be processed and what can be ignored as background. These observations lead to the prevalent hypothesis that feedback projections from ‘higher’ brain areas to more peripheral sensory areas are involved in processing of complex stimuli. However experimental analysis of signals conveyed by feedback projections in behaving animals is scarce. The nature of these signals and how they relate to behavior is unknown. Here I propose a cutting edge approach to directly record feedback signals in the olfactory system of behaving mice. We will use chronically implanted electrodes to record the modulation of olfactory bulb (OB) principal neurons by task related context. Additionally, we will record from piriform cortical (PC) neurons that project back to the OB. These will be tagged with channelrhodopsin-2 and identified by light sensitivity. Finally, we will express the spectrally distinct Ca++ indicators GCaMP6 and RCaMP2 in PC neurons and in olfactory sensory neurons, respectively, and use 2-photon microscopy to analyze the spatio-temporal relationship between feedforward and feedback inputs in the OB. This comprehensive approach will provide an explanation of how feedforward and feedback inputs are integrated to process complex stimuli.

1 500 000 €

Start date: 2018-04-01, End date: 2023-03-31

Cognition is a collective term for complex but sophisticated mental processes such as attention, learning, social interaction, language production, decision making and other executive functions. For normal brain function, these higher-order functions need to be aptly regulated and controlled, and the physiology and cellular substrates for cognitive functions are under intense investigation. The loss of cognitive control is intricately related to pathological states such as schizophrenia, depression, attention deficit hyperactive disorder and addiction. Synchronized neural activity can be observed when the brain performs several important functions, including cognitive processes. As an example, gamma activity (30-80 Hz) predicts the allocation of attention and theta activity (4-12 Hz) is tightly linked to memory processes. A large body of work indicates that the integrity of local and global neural synchrony is mediated by interneuron networks and actuated by the balance of different neuromodulators. However, much knowledge is still needed on the functional role interneurons play in cognitive processes, i.e. how the interneurons contribute to local and global network processes subserving cognition, and ultimately play a role in behavior. In addition, we need to understand how neuro-modulators, such as dopamine, regulate interneuron function. The proposed project aims to functionally determine the specific role the parvalbumin interneurons and the neuromodulator dopamine in aspects of cognition, and in behavior. In addition, we ask the question if cognition can be enhanced. We are employing a true multidisciplinary approach where brain activity is recorded in conjunctions with optogenetic manipulations of parvalbumin interneurons in animals performing cognitive tasks. In one set of experiments knock-down of dopamine receptors specifically in parvalbumin interneurons is employed to probe how this neuromodulator regulate network functions.

1 400 000 €

Start date: 2014-02-01, End date: 2019-01-31

More than a century after Wernicke and Broca established that speech perception and production rely on temporal and prefrontal cortices of the left brain hemisphere, the biological determinants for this organization are still unknown. While functional neuroanatomy has been described in great detail, the neuroscience of language still lacks a physiologically plausible model of the neuro-computational mechanisms for coding and decoding of speech acoustic signal. We propose to fill this gap by testing the biological validity and exploring the computational implications of one promising proposal, the Asymmetric Sampling in Time theory. AST assumes that speech signals are analysed in parallel at multiple timescales and that these timescales differ between left and right cerebral hemispheres. This theory is original and provocative as it implies that a single computational difference, distinct integration windows in right and left auditory cortices could be sufficient to explain why speech is preferentially processed by the left brain, and possible even why the human brain has evolved toward such an asymmetric functional organization. Our proposal has four goals: 1/ to validate, invalidate or amend AST on the basis of physiological experiments in healthy human subjects including functional magnetic resonance imaging (fMRI), combined electroencephalography (EEG) and fMRI, magnetoencephalography (MEG) and subdural electrocorticography (EcoG), 2/ to use computational modeling to probe those aspects of the theory that currently remain inaccessible to empirical testing (evaluation, assessment), 3/ to apply AST to binaural artificial hearing with cochlear implants, 4/ to test for disorders of auditory sampling in autism and dyslexia, two language neurodevelopmental pathologies in which a genetic basis implicates the physiological underpinnings of AST, and 5/ to assess potential generalisation of AST to linguistic action in the context of speech production.

1 500 000 €

Start date: 2011-02-01, End date: 2016-01-31

Neurodegenerative diseases (NDs) are incurable, debilitating conditions, arise mid-late in life, represent an enormous health and socioeconomic burden and no therapies exist. An enigmatic finding in NDs is the early and selective alteration in intrinsic excitability of vulnerable neurons paralleling changes in its circuitry. However, a gap in understanding exists in ND field about the cause of these alterations and whether these modifications regulate degenerative pathomechanisms. Our recent study, examining mechanisms of Purkinje cell (PC) degeneration in Spinocerebellar ataxia type 1 (SCA1) revealed that the earliest cerebellar alterations occur in the major excitatory inputs onto PCs, the climbing fibers (CFs). Based on this, we propose a novel three-step model of neurodegeneration: First, suboptimal functioning of the presynaptic inputs initiates signaling deficits in target PCs. Second, those alterations trigger maladaptive responses such as altered intrinsic PC excitability, thus amplifying pathogenic cascades. Third, at network level progressive dysfunction triggers compensatory synaptic modifications within the cerebellar circuitry. In this proposal, we will test our new hypothesis for NDs on SCA1 and this will be the first study to test circuit-dependency in NDs by selectively silencing presynaptic inputs and examining molecular responses in the postsynaptic neuron. Specifically, we will 1) Identify the dysfunctional CF associated molecular signature in PCs. 2) Elucidate mechanisms involved in altering intrinsic PC excitability. 3) Map the connectome for a structural correlate of the pathology. Using conditional mouse models, pharmacogenetics, transcriptomics, proteomics and connectomics, we will delineate molecular alterations that govern disease from compensatory alterations. Our systematic approach will not only impact SCA related therapies but the entire spectrum of NDs and has the potential to change the conceptual approach of future studies on NDs.

2 000 000 €

Start date: 2017-06-01, End date: 2022-05-31

Fear is an emotion that exerts powerful effects on our behavior and physiology. A large body of research implicates the amygdala in fear of painful stimuli, but virtually nothing is known about the circuits that support fear of predators and social threats, despite their primal importance in human behavior and pathology. Unlike painful stimuli, predator and social threats activate the medial hypothalamus, a cluster of highly conserved brain nuclei that control motivated behavior. Intriguingly, predator and social threats recruit largely non-overlapping nuclei in the medial hypothalamus, and we have recently demonstrated that separate medial hypothalamic circuits are essential for predator and social fear. We aim to build a functional wiring diagram of predator and social fear in the mouse that will explain how these fears are triggered, coordinated, and remembered. Such a functional wiring diagram will reveal the network logic of innate fear and put us in a position to selectively intervene in fear processing. Electrical stimulation of the medial hypothalamus in humans elicits panic responses and pharmacological agents that block these circuits will offer unexplored therapeutic approaches to treat anxiety disorders such as panic, social phobia, and post-traumatic stress disorder. Moreover, the relatively simple architecture of the medial hypothalamic fear network and its robust and direct behavioral readout in the mouse will be a powerful platform to test the role of several fundamental circuit features that are common to a wide range of behavioral networks, but whose function remains unknown, including the role of feedback loops, sparse cellular encoding of behavior, and overlapping processing of distinct behavioral responses. In this way, the project will provide the first circuit-level understanding of predator and social fear and answer a series of fundamental questions about how neural networks control behavior.

2 493 839 €

Start date: 2014-03-01, End date: 2019-02-28

Neurons in primary visual cortex (area V1) receive feedforward inputs from thalamic afferents and lateral inputs from other cortical neurons. Little is known about how these components interact to determine the responses of a V1 neuron. One camp ascribes most responses to feedforward mechanisms. The other camp ascribes them mostly to lateral interactions. We propose that these two apparently opposed views can be simply reconciled in a single framework. We hypothesize that area V1 can operate both in a feedforward regime and in a lateral interaction regime, depending on the nature of the stimulus and on the cognitive task at hand, and that the transition from one regime to the other is governed by synaptic inhibition. We will test these hypotheses by recording from individual V1 neurons while monitoring the activity of nearby populations of cortical neurons via multiprobe electrodes. In Aim 1 we will relate the activity of V1 neurons to that of nearby populations. We will use simple measures of correlation and nonlinear models that predict individual spikes to measure how responses depend on a feedforward contribution (the receptive field ) and on a lateral contribution (the connection field ). We will test our first hypothesis, concerning the role of the stimulus in changing this dependence. In Aim 2 we will extend these results to a behaving animal. We will record from V1 of mice performing a 2-alternative forced-choice psychophysical task, and we will test our second hypothesis, concerning the role of the cognitive task in determining the operating regime of the cortex. In Aim 3 we will seek a biophysical interpretation of the functional mechanisms and effective connectivity revealed by the previous Aims. We will test our third hypothesis, concerning the role of synaptic inhibition. The tools involved will include intracellular recordings and optical stimulation in transgenic mice whose cortical neurons are sensitive to light.

2 499 921 €

Start date: 2009-04-01, End date: 2014-03-31

The mammalian cerebral cortex was subject to a dramatic expansion in surface area during evolution. This process is recapitulated during development and is accompanied by folding of the cortical sheet, which allows fitting a large cortical surface within a limited cranial volume. A loss of cortical folds is linked to severe intellectual impairment in humans, so cortical folding is believed to be crucial for brain function. However, developmental mechanisms responsible for cortical folding, and the influence of this on cortical function, remain largely unknown. The goal of this proposal is to understand the genetic and cellular mechanisms that control the developmental expansion and folding of the cerebral cortex, and what is the impact of these processes on its functional organization. Human studies have identified genes essential for the proper folding of the human cerebral cortex. Genetic manipulations in mice have unraveled specific functions for some of those genes in the development of the cerebral cortex. But because the mouse cerebral cortex does not fold naturally, the mechanisms of cortical expansion and folding in larger brains remain unknown. We will study these mechanisms on ferret, an ideal model with a naturally folded cerebral cortex. We will combine the advantages of ferrets with cell biology, genetics and next-generation transcriptomics, together with state-of-the-art in vivo, in vitro and in silico approaches, including in vivo imaging of functional columnar maps. The successful execution of this project will provide insights into developmental and genetic risk factors for anomalies in human cortical topology, and into mechanisms responsible for the early formation of cortical functional maps.

1 701 116 €

Start date: 2013-01-01, End date: 2018-06-30

Amyotrophic Lateral Sclerosis (ALS) is the most common adult-onset neurodegenerative disease of the motor system, with a prevalence of 2-3/100 000. In spite of intensive research efforts, ALS remains an incurable disease and presents with a very severe prognosis, leading to patient death within 2 to 5 years following diagnosis. At the cellular level, ALS is characterized by the combined degeneration of both upper motor neurons (UMN, or corticospinal motor neurons) whose cell bodies are located in the cerebral cortex, and that extend axons to the medulla and spinal cord, and lower motor neurons (LMN, or spinal motor neurons) whose cell bodies are located in the medulla and spinal cord, and that connect to the skeletal muscles. This dual impairment allows to discriminate ALS from other, less severe diseases affecting either UMN or LMN. Despite this precise clinical description, it is striking to note that preclinical studies have so far mostly concentrated on LMN, leaving aside the role of UMN in ALS. This project aims at shedding light on the contribution of the dysfunction and/or the loss of UMN in ALS, in order to design and test new therapeutic strategies based on the protection and/or the replacement of this exact neuronal type. This innovative question has never been directly asked so far. Our working hypothesis is that specific neurodegeneration of UMN, in the course of ALS, does not represent an isolated side effect, but rather actively contributes to the onset and progression of the disease. Based on the discovery of new molecular players, and the development of alternative therapies, this original thematic has the ambition to provide clinicians and patients with new answers and new therapeutic assets.

1 500 000 €

Start date: 2015-04-01, End date: 2021-03-31

Understanding how brain controls social interactions is one of the central goals of neuroscience. Whereas social interactions and their effects on the emotional state of an individual are relatively well described at the behavioral level, much less is known about neural mechanisms involved in these very complex phenomena, especially in the amygdala, a key structure processing emotions in the brain. Recent investigations, mainly on fear learning and extinction, have shown that there are highly specialized neuronal circuits within the amygdala that control specific behaviors. However, a high density of interconnections, both among amygdalar nuclei and between amygdalar nuclei and other brain regions, and the lack of a predictable distribution of functional cell types make defining behavioral functions of the amygdalar neuronal circuits challenging. Therefore, to understand how different neuronal circuits in the amygdala produce different behaviors tracing anatomical connections between activated neurons, i.e., the functional anatomy is needed. Published data and our preliminary results suggest that within the amygdala there exist different neuronal circuits mediating social interactions of different valence (positive or negative affective significance) and that circuits controlling social and non-social emotions differ. Combining our recently developed behavioral models of adult, non-aggressive, same-sex social interactions with the methods of tracing anatomical connections between activated neurons, we plan to identify neural circuitry underlying social interactions of different emotional valence. This goal will be achieved by: (1) Characterizing functional anatomy of neuronal circuits in the amygdala underlying socially transferred emotions; (2) Examining role of the identified neuronal subpopulations in control of social behaviors; (3) Verifying role of matrix metalloproteinase-9-dependent neuronal subpopulations within the amygdala in social motivation.

1 312 500 €

Start date: 2016-12-01, End date: 2021-11-30

The regulated secretion of chemical signals in the brain occurs principally from two organelles, synaptic vesicles and dense core vesicles (DCVs). Synaptic vesicle secretion accounts for the well characterized local, fast signalling in synapses. DCVs contain a diverse collection of cargo, including many neuropeptides that trigger a multitude of modulatory effects with quite robust impact, for instance on memory, mood, pain, appetite or social behavior. Disregulation of neuropeptide secretion is firmly associated with many diseases such as cognitive and mood disorders, obesity and diabetes. In addition, many other signals depend on DCVs, for instance trophic factors and proteolytic enzymes, but also signals that typically do not diffuse like guidance cues and pre-assembled active zones. Hence, it is beyond doubt that DCV signalling is a central factor in brain communication. However, many fundamental questions remain open on DCV trafficking and secretion. Therefore, the aim of this proposal is to characterize the molecular principles that account for DCV delivery at release sites and their secretion. I will address 4 fundamental questions: What are the molecular factors that drive DCV fusion in mammalian CNS neurons? How does Ca2+ trigger DCV fusion? What are the requirements of DCV release sites and where do they occur? Can DCV fusion be targeted to synthetic release sites in vivo? I will exploit >30 mutant mouse lines and new cell biological and photonic approaches that allow for the first time a quantitative assessment of DCV-trafficking and fusion of many cargo types, in living neurons with a single vesicle resolution. Preliminary data suggest that DCV secretion is quite different from synaptic vesicle and chromaffin granule secretion. Together, these studies will produce the first systematic evaluation of the molecular identity of the core machinery that drives DCV fusion in neurons, the Ca2+-affinity of DCV fusion and the characteristics of DCV release sites.

2 439 315 €

Start date: 2013-05-01, End date: 2019-04-30

The principles of sensory perception are still a large experimental and theoretical puzzle. A strong difficulty is that perception emerges from networks of recurrently connected brain areas whose activity and function are poorly approximated by current generic mathematical models. These models also fail to explain many of the fundamental structures effortlessly identified by the brain (shapes, objects, auditory or tactile categories). I here propose to establish a new approach combining high-throughput population recoding methods with a tailored theoretical framework to derive computational principles operating throughout sensory systems and leading to biologically structured perception. This approach follows on the recent mathematical proposal, suggested by Deep Machine Learning methods, that complex perceptual objects emerge through series of simple nonlinear operations combining increasingly complex sensory features along the sensory pathways. Starting with the mouse auditory system as a model pathway, we will recursively extract, with model-free methods, the main nonlinear sensory features encoded in genetically tagged output and local neurons at different processing stages, using optical and electrophysiological high density recording techniques in awake animals. The role of these features in perception will be identified with behavioural assays. Specific intra- and interareal feedback connections, typically not included in Deep Leaning models, will be opto- and chemogenetically perturbed to assess their contribution to precise nonlinearities of the system and their role in the emergence of complex perceptual structures. Based on these structural, functional and perturbation data, a new generation of well-constrained and predictive sensory processing models will be built, serving as a platform to extract general computational principles missing to link neural activity to perception and to fuel artificial neural networks technologies.

1 983 886 €

Start date: 2018-09-01, End date: 2023-08-31