SEU-Allen Joint Center

Although 100+ years have passed since Santiago Ramón y Cajal was awarded the Nobel Prize for the neuron doctrine, we still lack an accepted catalog of neuron types and their names. This remains an important challenge, as it is a major goal of neuroscience to understand the relationship between the algorithms implemented by the brain and the hardware used to implement them. The 3D shape of a neuron—including its dendritic and axonal arbors — is central to determining its identity (phenotype), connectivity, synaptic integration, firing properties, and ultimately its role in the neural circuit. Characterizing and understanding the 3D morphology of individual neurons is fundamentally important for elucidating the breadth of neuronal diversity. Recent major neuroscience initiatives worldwide, such as the U.S. BRAIN Initiative, Europe’s Human Brain Project, and the Allen Cell Types Database are all based on the importance of understanding the diversity of cell types as a step toward elucidating the relationship between the structure and function in the nervous system. Quantifying the morphology of neurons and other tree-shaped biological structures (e.g., glial cells, brain vasculature, etc.) has been the focus of numerous studies over the past 30 years. Yet a systematic characterization of even simple brain circuits at the level of individual neurons is still limited by the lack of a robust system for fast and accurate reconstruction of neuronal branching arbors.