Project acronym GIANTSYN
Project Biophysics and circuit function of a giant cortical glutamatergic synapse
Researcher (PI) Peter Jonas
Host Institution (HI) INSTITUTE OF SCIENCE AND TECHNOLOGYAUSTRIA
Call Details Advanced Grant (AdG), LS5, ERC-2015-AdG
Summary A fundamental question in neuroscience is how the biophysical properties of synapses shape higher network
computations. The hippocampal mossy fiber synapse, formed between axons of dentate gyrus granule cells
and dendrites of CA3 pyramidal neurons, is the ideal synapse to address this question. This synapse is accessible
to presynaptic recording, due to its large size, allowing a rigorous investigation of the biophysical
mechanisms of transmission and plasticity. Furthermore, this synapse is placed in the center of a memory
circuit, and several hypotheses about its network function have been generated. However, even basic properties
of this key communication element remain enigmatic. The ambitious goal of the current proposal, GIANTSYN,
is to understand the hippocampal mossy fiber synapse at all levels of complexity. At the subcellular
level, we want to elucidate the biophysical mechanisms of transmission and synaptic plasticity in the
same depth as previously achieved at peripheral and brainstem synapses, classical synaptic models. At the
network level, we want to unravel the connectivity rules and the in vivo network function of this synapse,
particularly its role in learning and memory. To reach these objectives, we will combine functional and
structural approaches. For the analysis of synaptic transmission and plasticity, we will combine direct preand
postsynaptic patch-clamp recording and high-pressure freezing electron microscopy. For the analysis of
connectivity and network function, we will use transsynaptic labeling and in vivo electrophysiology. Based
on the proposed interdisciplinary research, the hippocampal mossy fiber synapse could become the first synapse
in the history of neuroscience in which we reach complete insight into both synaptic biophysics and
network function. In the long run, the results may open new perspectives for the diagnosis and treatment of
brain diseases in which mossy fiber transmission, plasticity, or connectivity are impaired.
Summary
A fundamental question in neuroscience is how the biophysical properties of synapses shape higher network
computations. The hippocampal mossy fiber synapse, formed between axons of dentate gyrus granule cells
and dendrites of CA3 pyramidal neurons, is the ideal synapse to address this question. This synapse is accessible
to presynaptic recording, due to its large size, allowing a rigorous investigation of the biophysical
mechanisms of transmission and plasticity. Furthermore, this synapse is placed in the center of a memory
circuit, and several hypotheses about its network function have been generated. However, even basic properties
of this key communication element remain enigmatic. The ambitious goal of the current proposal, GIANTSYN,
is to understand the hippocampal mossy fiber synapse at all levels of complexity. At the subcellular
level, we want to elucidate the biophysical mechanisms of transmission and synaptic plasticity in the
same depth as previously achieved at peripheral and brainstem synapses, classical synaptic models. At the
network level, we want to unravel the connectivity rules and the in vivo network function of this synapse,
particularly its role in learning and memory. To reach these objectives, we will combine functional and
structural approaches. For the analysis of synaptic transmission and plasticity, we will combine direct preand
postsynaptic patch-clamp recording and high-pressure freezing electron microscopy. For the analysis of
connectivity and network function, we will use transsynaptic labeling and in vivo electrophysiology. Based
on the proposed interdisciplinary research, the hippocampal mossy fiber synapse could become the first synapse
in the history of neuroscience in which we reach complete insight into both synaptic biophysics and
network function. In the long run, the results may open new perspectives for the diagnosis and treatment of
brain diseases in which mossy fiber transmission, plasticity, or connectivity are impaired.
Max ERC Funding
2 677 500 €
Duration
Start date: 2017-03-01, End date: 2022-02-28
Project acronym MiniBrain
Project Cerebral Organoids: Using stem cell derived 3D cultures to understand human brain development and neurological disorders
Researcher (PI) Juergen Knoblich
Host Institution (HI) INSTITUT FUER MOLEKULARE BIOTECHNOLOGIE GMBH
Call Details Advanced Grant (AdG), LS5, ERC-2015-AdG
Summary Most of our knowledge on human development and physiology is derived from experiments done in animal models. While these experiments have led to a comprehensive understanding of the principles of neurogenesis, animal models often fall short of modelling many of the most common neurological disorders. Recent experiments have revealed characteristic striking differences in brain development between rodents and primates and may provide an explanation for this problem.
The goal of this proposal is to use three dimensional organoid cultures derived from pluripotent human stem cells to reveal the human specific aspects of brain development and to analyse neurological disease mechanisms directly in human tissue. We have recently developed a 3D culture method allowing us to recapitulate human brain development during the first trimester of embryogenesis. Using this method, we will define the human specific brain patterning events in order to develop a culture system that can recapitulate essentially any part of the brain. Using a unique combination of cell type specific markers and mutagenic viruses, we will define the transcriptional networks defining specific neuronal subtypes. This will allow us to perform loss-of function genetics in human tissue to define transcription factors necessary for development of individual neuronal subtypes on a genome-wide level. Finally, we will apply the genome wide screening technology to human neurological disorders like microcephaly or schizophrenia to identify factors that can rescue disease phenotypes.
This research proposal will provide fundamental insights into the cellular and molecular mechanisms specifying various neuronal subclasses in the human brain and establish technology that can be applied to a variety of cell types and brain regions. The proposed experiments have the potential to yield fundamental insights into human neurological disease mechanisms that can currently not be derived from animal models.
Summary
Most of our knowledge on human development and physiology is derived from experiments done in animal models. While these experiments have led to a comprehensive understanding of the principles of neurogenesis, animal models often fall short of modelling many of the most common neurological disorders. Recent experiments have revealed characteristic striking differences in brain development between rodents and primates and may provide an explanation for this problem.
The goal of this proposal is to use three dimensional organoid cultures derived from pluripotent human stem cells to reveal the human specific aspects of brain development and to analyse neurological disease mechanisms directly in human tissue. We have recently developed a 3D culture method allowing us to recapitulate human brain development during the first trimester of embryogenesis. Using this method, we will define the human specific brain patterning events in order to develop a culture system that can recapitulate essentially any part of the brain. Using a unique combination of cell type specific markers and mutagenic viruses, we will define the transcriptional networks defining specific neuronal subtypes. This will allow us to perform loss-of function genetics in human tissue to define transcription factors necessary for development of individual neuronal subtypes on a genome-wide level. Finally, we will apply the genome wide screening technology to human neurological disorders like microcephaly or schizophrenia to identify factors that can rescue disease phenotypes.
This research proposal will provide fundamental insights into the cellular and molecular mechanisms specifying various neuronal subclasses in the human brain and establish technology that can be applied to a variety of cell types and brain regions. The proposed experiments have the potential to yield fundamental insights into human neurological disease mechanisms that can currently not be derived from animal models.
Max ERC Funding
2 800 000 €
Duration
Start date: 2017-01-01, End date: 2021-12-31
Project acronym NOVAMOX
Project Novel niches for anaerobic methane oxidation and their biogeochemical sigificance
Researcher (PI) Bo THAMDRUP
Host Institution (HI) SYDDANSK UNIVERSITET
Call Details Advanced Grant (AdG), PE10, ERC-2015-AdG
Summary Motivated by a series of recent discoveries, NOVAMOX provides the first comprehensive biogeochemical and microbial ecological analysis of methane consumption in anoxic freshwater systems and oceanic oxygen minimum zones, environments where such processes to date were largely ignored. I propose that anaerobic microbial methane oxidation pathways are important sinks in for methane in these environments, thereby affecting methane emissions and the cycling of nitrogen, iron, and sulfur, as the cycling of these elements is coupled either directly or indirectly to methane oxidation. With the development of new incubation and sensing techniques necessary to detect the processes in their environment, we will identify and quantify active pathways of anaerobic methane oxidation, identify the organisms that catalyse these transformations, analyse their environmental distribution, characterize kinetic controls of their growth and metabolic activity, and analyse the isotopic signatures they may leave behind. The project will generate robust estimates of the biogeochemical significance of anaerobic methane oxidation in these overlooked niches, and provide a quantitative mechanistic framework for analysis of the role of these processes in Earth’s biogeochemical evolution as well as for their implementation in forecasts of global change. The project will also provide fundamental new insights to the ecology of the highly specialized microorganisms involved in methane oxidation, for use in potential biotechnological applications.
Summary
Motivated by a series of recent discoveries, NOVAMOX provides the first comprehensive biogeochemical and microbial ecological analysis of methane consumption in anoxic freshwater systems and oceanic oxygen minimum zones, environments where such processes to date were largely ignored. I propose that anaerobic microbial methane oxidation pathways are important sinks in for methane in these environments, thereby affecting methane emissions and the cycling of nitrogen, iron, and sulfur, as the cycling of these elements is coupled either directly or indirectly to methane oxidation. With the development of new incubation and sensing techniques necessary to detect the processes in their environment, we will identify and quantify active pathways of anaerobic methane oxidation, identify the organisms that catalyse these transformations, analyse their environmental distribution, characterize kinetic controls of their growth and metabolic activity, and analyse the isotopic signatures they may leave behind. The project will generate robust estimates of the biogeochemical significance of anaerobic methane oxidation in these overlooked niches, and provide a quantitative mechanistic framework for analysis of the role of these processes in Earth’s biogeochemical evolution as well as for their implementation in forecasts of global change. The project will also provide fundamental new insights to the ecology of the highly specialized microorganisms involved in methane oxidation, for use in potential biotechnological applications.
Max ERC Funding
2 462 500 €
Duration
Start date: 2016-10-01, End date: 2021-09-30
Project acronym SINCHAIS
Project In situ analysis of single channel subunit composition in neurons: physiological implication in synaptic plasticity and behavior
Researcher (PI) Ryuichi Shigemoto
Host Institution (HI) INSTITUTE OF SCIENCE AND TECHNOLOGYAUSTRIA
Call Details Advanced Grant (AdG), LS5, ERC-2015-AdG
Summary Ligand-gated and voltage-gated channels are key molecules in transforming chemical signals into electrical ones and electrical signals into chemical ones, respectively. At excitatory synaptic connections in the brain, activation of AMPA- and NMDA-type glutamate receptors elicits inward currents at the postsynaptic sites, and activation of voltage-gated calcium channels triggers vesicle release of glutamate in the presynaptic sites. Plastic changes in their number, location and property can lead to potentiation or depression of synaptic efficacy, alteration in time course, and coupling to effectors at both postsynaptic and presynaptic sites. These channels are all composed of distinct subunits and their compositions affect channel properties, trafficking to the synaptic sites, and interaction with associated molecules, creating a large diversity of synaptic functions. Although channels with different subunit compositions have been investigated using biochemical and electrophysiological detection methods, very little is known about single channel subunit composition in situ because of the lack of high resolution methods for analysis of protein complex in intact tissues. In this project, I will develop novel technologies to visualize subunit composition at the single channel level in individual synapses by electron microscopy, combining new EM tags, freeze-fracture replica labelling, and electron tomography. Synaptic plasticity will be induced by optogenetic stimulation of identified neurons or behavioural paradigms to examine the dynamic changes of subunit composition. Finally, physiological implications of such regulation of subunit composition will be investigated by genetic manipulation of mice combined with electrophysiological and behavioural analyses. This work will demonstrate unprecedented views of the subunit composition in situ and provide new insights into how regulation of subunit composition contributes to synaptic plasticity and animal behaviour.
Summary
Ligand-gated and voltage-gated channels are key molecules in transforming chemical signals into electrical ones and electrical signals into chemical ones, respectively. At excitatory synaptic connections in the brain, activation of AMPA- and NMDA-type glutamate receptors elicits inward currents at the postsynaptic sites, and activation of voltage-gated calcium channels triggers vesicle release of glutamate in the presynaptic sites. Plastic changes in their number, location and property can lead to potentiation or depression of synaptic efficacy, alteration in time course, and coupling to effectors at both postsynaptic and presynaptic sites. These channels are all composed of distinct subunits and their compositions affect channel properties, trafficking to the synaptic sites, and interaction with associated molecules, creating a large diversity of synaptic functions. Although channels with different subunit compositions have been investigated using biochemical and electrophysiological detection methods, very little is known about single channel subunit composition in situ because of the lack of high resolution methods for analysis of protein complex in intact tissues. In this project, I will develop novel technologies to visualize subunit composition at the single channel level in individual synapses by electron microscopy, combining new EM tags, freeze-fracture replica labelling, and electron tomography. Synaptic plasticity will be induced by optogenetic stimulation of identified neurons or behavioural paradigms to examine the dynamic changes of subunit composition. Finally, physiological implications of such regulation of subunit composition will be investigated by genetic manipulation of mice combined with electrophysiological and behavioural analyses. This work will demonstrate unprecedented views of the subunit composition in situ and provide new insights into how regulation of subunit composition contributes to synaptic plasticity and animal behaviour.
Max ERC Funding
2 481 437 €
Duration
Start date: 2016-07-01, End date: 2021-06-30
Project acronym STC
Project Synaptic Tagging and Capture: From Synapses to Behavior
Researcher (PI) Sayyed Mohammad Sadegh Nabavi
Host Institution (HI) AARHUS UNIVERSITET
Call Details Starting Grant (StG), LS5, ERC-2015-STG
Summary It is shown that long-term potentiation (LTP) is the cellular basis of memory formation. However, since all but small fraction of memories are forgotten, LTP has been further divided into early LTP (e-LTP), the mechanism by which short-term memories are formed, and a more stable late LTP (L-LTP), by which long-term memories are formed. Remarkably, it has been shown that an e-LTP can be stabilized if it is preceded or followed by heterosynaptic L-LTP.
According to Synaptic Tagging and Capture (STC) hypothesis, e-LTP is stabilized by capturing proteins that are made by L-LTP induction. The model proposes that this mechanism underlies the formation of late associative memory, where the stability of a memory is not only defined by the stimuli that induce the change but also by events happening before and after these stimuli. As such, the model explicitly predicts that a short-term memory can be stabilized by inducing heterosynaptic L-LTP.
In this grant, I will put this hypothesis into test. Specifically, I will test two explicit predictions of STC model: 1) A naturally formed short-term memory can be stabilized by induction of heterosynaptic L-LTP. 2) This stabilization is caused by the protein synthesis feature of L-LTP. To do this, using optogenetics, I will engineer a short-term memory in auditory fear circuit, in which an animal transiently associates a foot shock to a tone. Subsequently, I will examine if optogenetic delivery of L-LTP to the visual inputs converging on the same population of neurons in the amygdala will stabilize the short-term tone fear memory.
To be able to engineer natural memory by manipulating synaptic plasticity I will develop two systems: 1) A two-color optical activation system which permits selective manipulation of distinct neuronal populations with precise temporal and spatial resolution; 2) An inducible and activity-dependent expression system by which those neurons that are activated by a natural stimulus will be optically tagged.
Summary
It is shown that long-term potentiation (LTP) is the cellular basis of memory formation. However, since all but small fraction of memories are forgotten, LTP has been further divided into early LTP (e-LTP), the mechanism by which short-term memories are formed, and a more stable late LTP (L-LTP), by which long-term memories are formed. Remarkably, it has been shown that an e-LTP can be stabilized if it is preceded or followed by heterosynaptic L-LTP.
According to Synaptic Tagging and Capture (STC) hypothesis, e-LTP is stabilized by capturing proteins that are made by L-LTP induction. The model proposes that this mechanism underlies the formation of late associative memory, where the stability of a memory is not only defined by the stimuli that induce the change but also by events happening before and after these stimuli. As such, the model explicitly predicts that a short-term memory can be stabilized by inducing heterosynaptic L-LTP.
In this grant, I will put this hypothesis into test. Specifically, I will test two explicit predictions of STC model: 1) A naturally formed short-term memory can be stabilized by induction of heterosynaptic L-LTP. 2) This stabilization is caused by the protein synthesis feature of L-LTP. To do this, using optogenetics, I will engineer a short-term memory in auditory fear circuit, in which an animal transiently associates a foot shock to a tone. Subsequently, I will examine if optogenetic delivery of L-LTP to the visual inputs converging on the same population of neurons in the amygdala will stabilize the short-term tone fear memory.
To be able to engineer natural memory by manipulating synaptic plasticity I will develop two systems: 1) A two-color optical activation system which permits selective manipulation of distinct neuronal populations with precise temporal and spatial resolution; 2) An inducible and activity-dependent expression system by which those neurons that are activated by a natural stimulus will be optically tagged.
Max ERC Funding
1 500 000 €
Duration
Start date: 2016-04-01, End date: 2021-03-31
Project acronym VISONby3DSTIM
Project Restoration of visual perception by artificial stimulation performed by 3D EAO microscopy
Researcher (PI) Jozsef Balázs Rózsa
Host Institution (HI) INSTITUTE OF EXPERIMENTAL MEDICINE - HUNGARIAN ACADEMY OF SCIENCES
Call Details Consolidator Grant (CoG), LS5, ERC-2015-CoG
Summary The long-term aim of the investigation is to assess the feasibility of creating an “artificial sense” and, thereby, a possible sensory (visual) prosthetic. While working towards this goal, we will have to address the question of how neural assembly activity relates to subjective perceptions. Finding and understanding these functional assemblies will make it possible to reactivate them in a precise, biologically relevant manner to elicit similar cortical activation as visual stimulation. Recent publications suggest that cortical connectivity can be mapped by two-photon microscopy. Here we want, therefore, to develop a novel 3D Electro-Acousto-Optical microscope for high-throughput assembly mapping. The microscope will be capable of scanning neuronal activity with one order of magnitude higher speed (300-500 kHz/ROI) and simultaneously photoactivate neurons with three order of magnitude higher efficiency (2,500 – 25,000 neurons/ms) than existing 3D microscopes while preserving the subcellular resolution required to simultaneously measure the somatic, the dendritic and axonal computation units in the entire V1 region of the cortex. The microscope will be based on our current 3D AO technology; on novel ultra-fast scanning technologies; new, 10-fold faster AO deflectors; and novel (multi-ROI) scanning strategies. Using our microscope in combination with novel caged neurotransmitters and optogenetic tools, we want to map cell assemblies and to understand how they form larger clusters and how they are associated with visual features. Furthermore, as a proof-of-concept of this grant, we want to restore visual perception by recreating previously mapped assembly patterns with 3D artificial photositmulation in behaving mice and see if the animal responds to the artificial stimulus in the same way as to the visual stimulus. Moreover, we want to restore visual information based spatial navigation in head restrained animals orienting and moving in a virtual labyrinth for reward.
Summary
The long-term aim of the investigation is to assess the feasibility of creating an “artificial sense” and, thereby, a possible sensory (visual) prosthetic. While working towards this goal, we will have to address the question of how neural assembly activity relates to subjective perceptions. Finding and understanding these functional assemblies will make it possible to reactivate them in a precise, biologically relevant manner to elicit similar cortical activation as visual stimulation. Recent publications suggest that cortical connectivity can be mapped by two-photon microscopy. Here we want, therefore, to develop a novel 3D Electro-Acousto-Optical microscope for high-throughput assembly mapping. The microscope will be capable of scanning neuronal activity with one order of magnitude higher speed (300-500 kHz/ROI) and simultaneously photoactivate neurons with three order of magnitude higher efficiency (2,500 – 25,000 neurons/ms) than existing 3D microscopes while preserving the subcellular resolution required to simultaneously measure the somatic, the dendritic and axonal computation units in the entire V1 region of the cortex. The microscope will be based on our current 3D AO technology; on novel ultra-fast scanning technologies; new, 10-fold faster AO deflectors; and novel (multi-ROI) scanning strategies. Using our microscope in combination with novel caged neurotransmitters and optogenetic tools, we want to map cell assemblies and to understand how they form larger clusters and how they are associated with visual features. Furthermore, as a proof-of-concept of this grant, we want to restore visual perception by recreating previously mapped assembly patterns with 3D artificial photositmulation in behaving mice and see if the animal responds to the artificial stimulus in the same way as to the visual stimulus. Moreover, we want to restore visual information based spatial navigation in head restrained animals orienting and moving in a virtual labyrinth for reward.
Max ERC Funding
2 000 000 €
Duration
Start date: 2016-05-01, End date: 2021-04-30
Project acronym WIRELESS
Project Motor and cognitive functions of the monkey premotor cortex during free social interactions
Researcher (PI) Luca Bonini
Host Institution (HI) UNIVERSITA DEGLI STUDI DI PARMA
Call Details Starting Grant (StG), LS5, ERC-2015-STG
Summary A number of studies demonstrated that the primates’ premotor cortex (PM) plays a crucial role not only in organizing movement, but also in perceptual and socio-cognitive functions. However, these studies have been carried out in laboratory settings, which deeply limit the possibility to understand the neural mechanisms underlying natural behaviours. To solve this problem, I propose a new approach consisting in a two-steps chronic recording of monkey PM neurons: first, single neurons response properties will be characterized in a traditional, head-restrained laboratory setting; then, in the same session, the same neurons activity will be recorded wirelessly during free interactions of the monkey with its physical and social environment. The project will initially focus on neurons belonging to the forelimb representation of the ventral (i.e. areas F4 and F5) and dorsal (area F2vr) PM, putatively well known for their role in sensorimotor transformations, goal coding, representation of space, and recognition of other’s observed actions. The same paradigm will then be applied to the study of the mesial pre-supplementary area F6, a crucial bridge between prefrontal and PM regions whose role in socio-cognitive functions remains still virtually unknown. Finally, by simultaneous, chronic recording of neuronal activity from lateral and mesial PM, we will first assess the functional interactions between these areas in both laboratory and natural settings, and then we will probe causality in these interactions by chemically manipulating neuronal activity of one region (i.e. F6) while recording from the other one (i.e. F5). The project will reveal the role of premotor cortex in motor and social functions during natural behaviours. In addition, it might open up new possibilities for future studies of neural plasticity and reorganization of ethologically-relevant motor, cognitive and social functions following chemical manipulation of neural activity and virtual brain lesions.
Summary
A number of studies demonstrated that the primates’ premotor cortex (PM) plays a crucial role not only in organizing movement, but also in perceptual and socio-cognitive functions. However, these studies have been carried out in laboratory settings, which deeply limit the possibility to understand the neural mechanisms underlying natural behaviours. To solve this problem, I propose a new approach consisting in a two-steps chronic recording of monkey PM neurons: first, single neurons response properties will be characterized in a traditional, head-restrained laboratory setting; then, in the same session, the same neurons activity will be recorded wirelessly during free interactions of the monkey with its physical and social environment. The project will initially focus on neurons belonging to the forelimb representation of the ventral (i.e. areas F4 and F5) and dorsal (area F2vr) PM, putatively well known for their role in sensorimotor transformations, goal coding, representation of space, and recognition of other’s observed actions. The same paradigm will then be applied to the study of the mesial pre-supplementary area F6, a crucial bridge between prefrontal and PM regions whose role in socio-cognitive functions remains still virtually unknown. Finally, by simultaneous, chronic recording of neuronal activity from lateral and mesial PM, we will first assess the functional interactions between these areas in both laboratory and natural settings, and then we will probe causality in these interactions by chemically manipulating neuronal activity of one region (i.e. F6) while recording from the other one (i.e. F5). The project will reveal the role of premotor cortex in motor and social functions during natural behaviours. In addition, it might open up new possibilities for future studies of neural plasticity and reorganization of ethologically-relevant motor, cognitive and social functions following chemical manipulation of neural activity and virtual brain lesions.
Max ERC Funding
1 499 338 €
Duration
Start date: 2016-10-01, End date: 2021-09-30
