Generation of an interactive online atlas of developmental neuroanatomy of the zebrafish brain

For the brain to properly function, many highly complex events need to occur in a highly coordinated way during embryonic development. Nerve cells, or neurons, need to be generated in the correct locations with the correct identities and in the correct numbers. The neurons must establish connections with other neurons often located in far distant regions of the central nervous system. Somehow, all these events occur with precision and accuracy and the brain is able to process sensory input and direct motor output. One major goal for researchers is to understand how neurons are connected in the circuits that regulate behaviours. Given the billions of neurons in the adult human brain, this is an impossible task with currently available technologies. However, in simpler model systems, it is more feasible to attempt to describe the full repertoire of neurons and their connections as a prelude to understanding how the neurons function in neural circuits and malfunction in neurological conditions. In this project, we will use high resolution imaging techniques to examine and document the repertoire of neurons and their connections in the developing zebrafish brain over the first few days of development. This is a very timely project as thousands of discrete populations of fish in which different subsets of neurons in the brain are specifically labelled have recently been generated. Together with other approaches such as labelling individual neurons in the intact brain, analysis of these lines will allow us to construct the highest resolution atlas of developmental neuroanatomy and connectivity in any vertebrate animal. This atlas will be available to the community in the form of a user-friendly web-based database that will allow the user to navigate around the brain, homing in on structures of primary interest. The database will house text, images and some movies, all aimed at presenting the full extent of current knowledge about the specific neural structures. The atlas will be the leading resource of its kind and we anticipate that it will be very widely used throughout the international scientific community. We will also maintain many of the fish lines with subsets of neurons labelled in the brain as these will be an excellent resource for neuroscience research in the community.

Perhaps the greatest challenge for the developmental neuroscience community is to understand how genes build the neuronal circuits that control behaviours. The lack of knowledge about how neurons in the brain are interconnected in the relatively simple circuits that mediate the animal's first behavioural responses is a major bottleneck in the field. However, this is set to change due to the availability of new resources, most notably transgenic animals in which discrete subsets of neurons are labelled, that facilitate the reconstruction of neuronal projections and circuitry. The zebrafish is set to become a leading model for studies of circuitry and nervous system function and is the best model for resolving the developmental neuroanatomy of the CNS. The embryo is small enough that the intact brain can be imaged at high resolution by confocal microscopy. Coupled with almost unlimited numbers of transgenic lines in which subsets of neurons are labelled, one can envisage being able to identify all major neuronal subgroups in the developing brain, their patterns of dendritic and axonal projections and their likely connections. To exploit these novel resources and tools, in pilot studies, we have developed a relational database of annotated and searchable neuroanatomical images of the zebrafish brain over the first 5 days of development. In this project, we will develop this resource into an open access, high-resolution developmental neuroanatomy atlas, the leading resource of its kind. We will develop bioinformatic tools to annotate and present data and will expand content, mostly through screening and imaging large numbers of transgenic lines. Images, and in some cases, movies will be presented alongside tutorials detailing the current state of knowledge of neuroanatomical structures. We will also maintain many of the lines that we characterise as a resource for research in the UK and wider communities.

Who will benefit from this research? One output of this project will be an online atlas of neuroanatomical information that is easily accessible to the entire zebrafish and wider neuroscience communities. The project will foster international collaborations between academic scientists by sharing data and resources to those working on brain structures in health and disease. In addition to academic scientists in the field, our work is likely to be of long-term benefit to clinically oriented colleagues and those working in biotech and pharmaceutical industries who lack suitable models/information for drug screening and other neurology related activities. Outside of the academic, clinical and commercial sector, our work will have impact on students in other fields of study including school children, and upon the general public. How will they benefit from this research? Understanding the connectivity of the developing and mature brain is an immense challenge that is important to underpin many aspects of biological science, as well as having impact on human wellbeing. Our project will contribute to global efforts to resolve connections in the vertebrate brain. Information from such projects will facilitate planning and undertaking of experiments addressing how circuits drive behaviour and will help to resolve the nature of connectivity defects in neurological conditions. Provision of resources such as well-characterised transgenic lines labelling discrete groups of neurons will facilitate the ability of academic, clinical or pharmaceutical/biotech investigators to address how such neurons are generated and maintained, the consequences of their loss and the effects of small molecules and drugs upon their generation/maintenance. Such studies could impact upon our understanding and treatment of the many neurological conditions in which neuronal connectivity or maintenance of neurons is affected. Our experience is that school children and students in non-scientific fields are fascinated when introduced to scientific research in the lab or through presentations. Such exposure can direct career decisions and can inspire creativity in the students' own areas of expertise (1). The public benefits from a better understanding of science and scientific terms and a more intangible appreciation of the beauty of the developing embryo. What will be done to ensure that they benefit from this research? In addition to publishing in high profile scientific journals, we present our work online where anyone can download our publications and read about ongoing projects prior to publication. The atlas itself will be completely open-access and other bona-fide web sites will be able to use our images for academic purposes. We also write public-friendly reports of all of our publications and research projects [1,2] - these help to ensure that the media understand and accurately report our work (3) and it enables the public to gain an understanding of cutting edge research without having to have a background in science. It also allows researchers in more clinically or pharmaceutically oriented settings to gain an appreciation of how our research could be used to facilitate their own work. We undertake a lot of outreach activity [4], including placements of school kids in the lab, school visits, talks to nonscientific audiences, and web presentations. Our images are widely used in museums, for UCL publicity and other uses. Subject to any MTA agreements from third parties, we share all tools and transgenic fish lines generated during this project with anyone who is interested in using them. [1] www.ucl.ac.uk/zebrafish-group/outreach/summaries/index.php [2] http://www.ucl.ac.uk/zebrafish-group/research/researchSteve.php [3] http://www.livescience.com/health/090122-brain-asymmetry.html [4] www.ucl.ac.uk/zebrafish-group/outreach/