Project acronym YODA
Project Topographic signaling and spatial landmarks of key polarized neuro-developmental processes
Researcher (PI) Valérie Lucienne Corinne Castellani
Host Institution (HI) CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
Call Details Starting Grant (StG), LS5, ERC-2011-StG_20101109
Summary Polarization, which confers asymmetry at molecular, cellular and tissue scales, is a fascinating process establishing fundamental features of biological systems. In multicellular organisms, symmetry breaking triggers the specification of embryonic body axes, governing the positioning of subsequent morphogenetic processes. Cells and tissues acquire complex polarity features, which remarkably, are highly precisely positioned within the body axes. How are polarization processes spatially oriented remlains fully enigmatic. During the formation of the nervous system, some crucial processes are polarized. Likewise, the navigation of neuronal projections in the body is a typical polarized process, axons selecting specific pathways to reach their targets. Studies in this field established crucial roles for topographic cues in controlling the polarized growth of neuronal projections. Up to now, my lab has focused on axon guidance mechanisms and while investigating the links between spatial position and neural circuit formation, I became convinced that topographic signalling must be equally required to set other key polarized processes of the developing nervous system. For example in the neuroepithelium, progenitor division is polarized along the apico-basal axis of the neural tube. Likewise in the young post-mitotic neuron, precise coordinates along the body axes define the site where the axon emerges. First, we postulate the existence of a topographic signaling giving to neuronal cells (but this might be a more general case) landmarks of the different embryonic axes so that polarization takes place with appropriate spatial orientation. Second, we make the assumption that this topographic signalling is ensured by cues initially identified for their role during axon navigation. Our goals are to explore these issues, using as a model the sensorimotor circuits, where several processes can be investigated for questioning the interplay between polarity and topography.
Summary
Polarization, which confers asymmetry at molecular, cellular and tissue scales, is a fascinating process establishing fundamental features of biological systems. In multicellular organisms, symmetry breaking triggers the specification of embryonic body axes, governing the positioning of subsequent morphogenetic processes. Cells and tissues acquire complex polarity features, which remarkably, are highly precisely positioned within the body axes. How are polarization processes spatially oriented remlains fully enigmatic. During the formation of the nervous system, some crucial processes are polarized. Likewise, the navigation of neuronal projections in the body is a typical polarized process, axons selecting specific pathways to reach their targets. Studies in this field established crucial roles for topographic cues in controlling the polarized growth of neuronal projections. Up to now, my lab has focused on axon guidance mechanisms and while investigating the links between spatial position and neural circuit formation, I became convinced that topographic signalling must be equally required to set other key polarized processes of the developing nervous system. For example in the neuroepithelium, progenitor division is polarized along the apico-basal axis of the neural tube. Likewise in the young post-mitotic neuron, precise coordinates along the body axes define the site where the axon emerges. First, we postulate the existence of a topographic signaling giving to neuronal cells (but this might be a more general case) landmarks of the different embryonic axes so that polarization takes place with appropriate spatial orientation. Second, we make the assumption that this topographic signalling is ensured by cues initially identified for their role during axon navigation. Our goals are to explore these issues, using as a model the sensorimotor circuits, where several processes can be investigated for questioning the interplay between polarity and topography.
Max ERC Funding
1 498 971 €
Duration
Start date: 2012-04-01, End date: 2017-03-31
Project acronym ZEBRAFISH PERCEPTION
Project Sensory perception: neural representation and modulation
Researcher (PI) German Sumbre
Host Institution (HI) INSTITUT NATIONAL DE LA SANTE ET DE LA RECHERCHE MEDICALE
Call Details Starting Grant (StG), LS5, ERC-2009-StG
Summary Perception has intrigued philosophers and scientists since Aristotle ~2,300 years ago, but only recently it became technically possible to address its underlying neural mechanisms. The main scientific research approach still focuses on studying the evoked responses to a perceived sensory stimulus. However, in a state of sensory deprivation, sensory areas in the brain remain highly active. This activity, once interpreted as irrelevant noise, has been found to exhibit highly coherent spatiotemporal structures, suggesting a possible role in perception. Here, I propose to test the hypothesis that perception results as a consequence of the interaction between the dynamic internal state of the brain and the activity evoked by sensory experience. For this purpose, I shall use the zebrafish larva as the experimental model, and a multidisciplinary approach involving two-photon imaging of neural network activities with single cell resolution, behavioural assays, novel mathematical methods for data analysis and genetic engineering techniques to label and manipulate activity of specific cell types or entire networks. The zebrafish model offers the advantage of combining simultaneously all these techniques in an intact behaving vertebrate. I shall specifically examine: 1) The Neuronal representation of sensory perception 2) The role of ongoing spontaneous activity in sensory perception 3) The effect of sensory experience on perception The proposed multidisciplinary approach will shed new light on how information flows through the nervous system; how sensory stimuli are detected, processed and converted into motor behaviours. The findings of this project should provide clear hypotheses regarding analogous and poorly-understood processes in mammals. The work could therefore contribute to understanding of neurological disorders, such as tinnitus, phantom limb and other hallucinations, in which sensory experience is perceived in the absence of external stimulation.
Summary
Perception has intrigued philosophers and scientists since Aristotle ~2,300 years ago, but only recently it became technically possible to address its underlying neural mechanisms. The main scientific research approach still focuses on studying the evoked responses to a perceived sensory stimulus. However, in a state of sensory deprivation, sensory areas in the brain remain highly active. This activity, once interpreted as irrelevant noise, has been found to exhibit highly coherent spatiotemporal structures, suggesting a possible role in perception. Here, I propose to test the hypothesis that perception results as a consequence of the interaction between the dynamic internal state of the brain and the activity evoked by sensory experience. For this purpose, I shall use the zebrafish larva as the experimental model, and a multidisciplinary approach involving two-photon imaging of neural network activities with single cell resolution, behavioural assays, novel mathematical methods for data analysis and genetic engineering techniques to label and manipulate activity of specific cell types or entire networks. The zebrafish model offers the advantage of combining simultaneously all these techniques in an intact behaving vertebrate. I shall specifically examine: 1) The Neuronal representation of sensory perception 2) The role of ongoing spontaneous activity in sensory perception 3) The effect of sensory experience on perception The proposed multidisciplinary approach will shed new light on how information flows through the nervous system; how sensory stimuli are detected, processed and converted into motor behaviours. The findings of this project should provide clear hypotheses regarding analogous and poorly-understood processes in mammals. The work could therefore contribute to understanding of neurological disorders, such as tinnitus, phantom limb and other hallucinations, in which sensory experience is perceived in the absence of external stimulation.
Max ERC Funding
1 851 600 €
Duration
Start date: 2009-11-01, End date: 2015-09-30
Project acronym ZEBRATECTUM
Project Anatomical and Functional Dissection of Neural Circuits in the Zebrafish Optic Tectum
Researcher (PI) Filippo Del Bene
Host Institution (HI) INSTITUT CURIE
Call Details Starting Grant (StG), LS5, ERC-2012-StG_20111109
Summary The optic tectum has emerged as a tractable visuomotor transformer, in which anatomical and functional studies can allow a better understanding of how behavior is controlled by neuronal circuits. We plan to examine the formation and function of the visual system in zebrafish larvae using in vivo time-lapse microscopy and state-of-the-art “connectomic” and “optogenetic” approaches to monitor and perturb neuronal activity. We will apply complementary cellular and molecular analyses to dissect this circuit and identify the neuronal substrate of visual behaviors. We will start by analyzing the function, development and connectivity of a newly characterized class of inhibitory interneurons located in the superficial part of the tectal neuropil named SINs (superficial inhibitory interneurons) that I have previously identified. Our work based on functional imaging has placed SINs at the center of a tectal micro-circuit for size tuning of visual stimuli. We will dissect this working model by analyzing the physiological properties of SINs. We also will investigate their development and connectivity at the level of single synapses by imaging these cells in vivo using fluorescent reporters in transgenic animals. We will then study how SINs migrate to their final position in the superficial tectum away from the zone where they are initially generated and how their processes direct tectal synaptic lamina formation. SINs are the only tectal cells expressing Reelin and we will analyze the role of this pathway in tectal development and proper synaptic lamination in the tectal neuropil. Our multidisciplinary approach aims to describe in great detail the formation and function of a neuronal circuit crucial for visual function, establishing this model for neural circuits studies in vertebrates.
Summary
The optic tectum has emerged as a tractable visuomotor transformer, in which anatomical and functional studies can allow a better understanding of how behavior is controlled by neuronal circuits. We plan to examine the formation and function of the visual system in zebrafish larvae using in vivo time-lapse microscopy and state-of-the-art “connectomic” and “optogenetic” approaches to monitor and perturb neuronal activity. We will apply complementary cellular and molecular analyses to dissect this circuit and identify the neuronal substrate of visual behaviors. We will start by analyzing the function, development and connectivity of a newly characterized class of inhibitory interneurons located in the superficial part of the tectal neuropil named SINs (superficial inhibitory interneurons) that I have previously identified. Our work based on functional imaging has placed SINs at the center of a tectal micro-circuit for size tuning of visual stimuli. We will dissect this working model by analyzing the physiological properties of SINs. We also will investigate their development and connectivity at the level of single synapses by imaging these cells in vivo using fluorescent reporters in transgenic animals. We will then study how SINs migrate to their final position in the superficial tectum away from the zone where they are initially generated and how their processes direct tectal synaptic lamina formation. SINs are the only tectal cells expressing Reelin and we will analyze the role of this pathway in tectal development and proper synaptic lamination in the tectal neuropil. Our multidisciplinary approach aims to describe in great detail the formation and function of a neuronal circuit crucial for visual function, establishing this model for neural circuits studies in vertebrates.
Max ERC Funding
1 920 000 €
Duration
Start date: 2013-01-01, End date: 2018-06-30
Project acronym ZFISHSLEEP
Project Resolving the Neuropharmacology and Genetics of Zebrafish Sleep
Researcher (PI) Jason Rihel
Host Institution (HI) UNIVERSITY COLLEGE LONDON
Call Details Starting Grant (StG), LS5, ERC-2011-StG_20101109
Summary Sleep is a fundamental process, yet the genetic and neural mechanisms that regulate sleep are largely unknown. We have developed the zebrafish as a model system to study the regulation of sleep because it combines the genetics of invertebrates with the basic brain structures that regulate sleep in humans. We previously designed high throughput behavioural assays to measure sleep behaviours in the fish and used genetic tools to demonstrate that the wake-regulating hypocretin/orexin (Hcrt) system is functionally conserved in the zebrafish. We have also used our assays to perform a small molecule screen and identified both conserved and novel candidate regulators of sleep in zebrafish.
In Aim 1, we will observe the behaviour of wild type and Hcrt receptor mutants to a panel of small molecules known to alter zebrafish sleep. This aim tests the hypothesis that these compounds exert their effects on sleep and wake through the Hcrt system. In Aim 2, we will follow-up on the compounds that had differential effects in the mutants. We will monitor the activity of Hcrt neurons in response to drugs using a new neuroluminescent technique to observe the activity of neurons in freely behaving zebrafish larvae. This Aim will extend the behavioural data to the level of neural circuits. In Aim 3, we will use new methods to globally observe neuronal activity in the zebrafish brain to extend our analysis to neurons thought to interact with the Hcrt system. By observing activity across the sleep/wake cycle, we may also uncover novel sleep regulating neurons.
Overall, this project takes a multidisciplinary approach to the study of sleep and the Hcrt system, leveraging new methods from chemical biology, molecular genetics, and behavioural neuroscience in the zebrafish. As little is known about the mechanisms and sites of action for most sleep-altering compounds, any progress would advance the sleep field and could have clinical relevance to the treatment of sleep disorders.
Summary
Sleep is a fundamental process, yet the genetic and neural mechanisms that regulate sleep are largely unknown. We have developed the zebrafish as a model system to study the regulation of sleep because it combines the genetics of invertebrates with the basic brain structures that regulate sleep in humans. We previously designed high throughput behavioural assays to measure sleep behaviours in the fish and used genetic tools to demonstrate that the wake-regulating hypocretin/orexin (Hcrt) system is functionally conserved in the zebrafish. We have also used our assays to perform a small molecule screen and identified both conserved and novel candidate regulators of sleep in zebrafish.
In Aim 1, we will observe the behaviour of wild type and Hcrt receptor mutants to a panel of small molecules known to alter zebrafish sleep. This aim tests the hypothesis that these compounds exert their effects on sleep and wake through the Hcrt system. In Aim 2, we will follow-up on the compounds that had differential effects in the mutants. We will monitor the activity of Hcrt neurons in response to drugs using a new neuroluminescent technique to observe the activity of neurons in freely behaving zebrafish larvae. This Aim will extend the behavioural data to the level of neural circuits. In Aim 3, we will use new methods to globally observe neuronal activity in the zebrafish brain to extend our analysis to neurons thought to interact with the Hcrt system. By observing activity across the sleep/wake cycle, we may also uncover novel sleep regulating neurons.
Overall, this project takes a multidisciplinary approach to the study of sleep and the Hcrt system, leveraging new methods from chemical biology, molecular genetics, and behavioural neuroscience in the zebrafish. As little is known about the mechanisms and sites of action for most sleep-altering compounds, any progress would advance the sleep field and could have clinical relevance to the treatment of sleep disorders.
Max ERC Funding
1 902 750 €
Duration
Start date: 2012-02-01, End date: 2017-01-31
