Only limited information is provided on morphology, densities, and spatial organization. However, the currently available systems primarily capture the presence of connections. Systematic efforts to create connectivity databases building on published axonal tracing data – have proven helpful for combining key information from a multitude of experimental investigations.
Axonal tracing studies yield highly specific, detailed visualizations of axonal connections in histological sections. An intermediate level of analysis is delivered by use of axonal tract-tracing methods, which is suitable for mapping the specific axonal connections of limited populations of neurons –, see also ). Axonal pathways can be studied at various levels of granularity, ranging from mapping of major fiber pathways (trajectories) using macroscopic dissection or novel magnetic resonance imaging (MRI) based tractography techniques –, to detailed reconstruction of individual axons and synaptic contacts using confocal or electron microscopy –. The axonal pathways they form make up the wiring of the brain, an important basis for understanding of brain functions under normal as well as pathological conditions –. The vast numbers of neurons in the brain are connected with a hugely larger number of synapses. The present study is a contribution to a systematic mapping of rodent brain connections and represents a starting point for further large-scale mapping efforts.
The accuracy of the approach is validated by comparing results generated with our system with findings reported in previous publications. We here present the workflow and the data system, and exemplify how the online image repository can be used to map different aspects of the brain-wide connectivity of the rat primary somatosensory cortex, including not only presence of connections but also morphology, densities, and spatial organization. The system is available online through the Rodent Brain WorkBench ( Whole Brain Connectivity Atlas) and holds experimental metadata and high-resolution images of histological sections from experiments in which axonal tracers were injected in the primary somatosensory cortex. To explore more efficient ways of mapping, analyzing, and sharing detailed axonal connectivity data from the rodent brain, we have implemented a workflow for data production and developed an atlas system tailored for online presentation of axonal tracing data. Since journal publications typically only accommodate restricted data descriptions and example images, literature search is a cumbersome way to retrieve overviews of brain connectivity.
Such connectivity data are typically generated in neuroanatomical tract-tracing experiments in which specific axonal connections are visualized in histological sections. Detailed knowledge about the anatomical organization of axonal connections is important for understanding normal functions of brain systems and disease-related dysfunctions.
0 kommentar(er)
