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