From Neurons to Behavior: Visual Analytics Methods for Heterogeneous Spatial Big Brain Data
Florian Johann Ganglberger
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Advances in neuro-imaging have allowed big brain initiatives and consortia to create vast resources of brain data that can be mined for insights into mental processes and biological principles. Research in this area does not only relate to mind and consciousness, but also to the understanding of many neurological disorders, such as Alzheimers disease, autism, and anxiety. Exploring the relationships between genes, brain circuitry, and behavior is therefore a key element in research that requires the joint analysis of a heterogeneous set of spatial brain data, including 3D imaging data, anatomical data, and brain networks at varying scales, resolutions, and modalities. Due to high-throughput imaging platforms, this datas size and complexity goes beyond the state-of-the-art by several orders of magnitude. Current analytical workflows involve time-consuming manual data aggregation and extensive computational analysis in script-based toolboxes. Visual analytics methods for exploring big brain data can support neuroscientists in this process, so they can focus on understanding the data rather than handling it. In this thesis, several contributions that target this problem are presented. The first contribution is a computational method that fuses genetic information with spatial gene expression data and connectivity data to predict functional neuroanatomical maps. These maps indicate, which brain areas might be related to a specific function or behavior. The approach has been applied to predict yet unknown functional neuroanatomy underlying multigeneic behavioral traits identified in genetic association studies and has demonstrated that rather than being randomly distributed throughout the brain, functionally-related gene sets accumulate in specific networks. The second contribution is the creation of a data structure that enables the interactive exploration of big brain network data with billions of edges. By utilizing the resulting hierarchical and spatial organization of the data, this approach allows neuroscientists on-demand queries of incoming/outgoing connections of arbitrary regions of interest on different anatomical scales. These queries would otherwise exceed the limits of current consumer level PCs. The data structure is used in the third contribution, a novel web-based framework to explore neurobiological imaging and connectivity data of different types, modalities, and scale. It employs a query-based interaction scheme to retrieve 3D spatial gene expressions and various types of connectivity to enable an interactive dissection of networks in real-time with respect to their genetic composition. The data is related to a hierarchical organization of common anatomical atlases that enables neuroscientists to compare multimodal networks on different scales in their anatomical context. Furthermore, the framework is designed to facilitate collaborative work with shareable comprehensive workflows on the web. As a result, the approaches presented in this thesis may assist neuroscientists to refine their understanding of the functional organization of the brain beyond simple anatomical domains and expand their knowledge about how our genes affect our mind.