Article

An Integrated Micro- and Macroarchitectural Analysis of the Drosophila Brain by Computer-Assisted Serial Section Electron Microscopy

University of Texas at Austin, United States of America
PLoS Biology (Impact Factor: 11.77). 10/2010; 8(10). DOI: 10.1371/journal.pbio.1000502
Source: PubMed

ABSTRACT The analysis of microcircuitry (the connectivity at the level of individual neuronal processes and synapses), which is indispensable for our understanding of brain function, is based on serial transmission electron microscopy (TEM) or one of its modern variants. Due to technical limitations, most previous studies that used serial TEM recorded relatively small stacks of individual neurons. As a result, our knowledge of microcircuitry in any nervous system is very limited. We applied the software package TrakEM2 to reconstruct neuronal microcircuitry from TEM sections of a small brain, the early larval brain of Drosophila melanogaster. TrakEM2 enables us to embed the analysis of the TEM image volumes at the microcircuit level into a light microscopically derived neuro-anatomical framework, by registering confocal stacks containing sparsely labeled neural structures with the TEM image volume. We imaged two sets of serial TEM sections of the Drosophila first instar larval brain neuropile and one ventral nerve cord segment, and here report our first results pertaining to Drosophila brain microcircuitry. Terminal neurites fall into a small number of generic classes termed globular, varicose, axiform, and dendritiform. Globular and varicose neurites have large diameter segments that carry almost exclusively presynaptic sites. Dendritiform neurites are thin, highly branched processes that are almost exclusively postsynaptic. Due to the high branching density of dendritiform fibers and the fact that synapses are polyadic, neurites are highly interconnected even within small neuropile volumes. We describe the network motifs most frequently encountered in the Drosophila neuropile. Our study introduces an approach towards a comprehensive anatomical reconstruction of neuronal microcircuitry and delivers microcircuitry comparisons between vertebrate and insect neuropile.

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    • "It recovers the crisp image of these structures and facilitates recognition of neural structures. The experiments on Drosophila first instar larva ventral nerve cord (VNC) dataset Cardona and et al. (2010) demonstrate significant improvement over the baselines. "
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    • "Serial section transmission electron microscopy (ssTEM) [1] of brain tissue is an important example. "
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    ABSTRACT: In biological imaging the data is often represented by a sequence of anisotropic frames — the resolution in one dimension is significantly lower than in the other dimensions. E.g. in electron microscopy it arises from the thickness of a scanned section. This leads to blurred images and raises problems in tasks like neuronal image segmentation. We present an approach called SuperSlicing to decompose the observed frame into a sequence of plausible hidden sub-frames. Based on sub-frame decomposition by SuperSlicing we propose a novel automated method to perform neuronal structure segmentation. We test our approach on a popular benchmark, where SuperSlicing preserves topological structures significantly better than other algorithms.
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    • "With the recent advancements in the automated collection of large image datasets of nano-scale Electron Microscopy (EM) images of brain tissue [1] [2], have resulted in interest in the neuroscience community to develop computational algorithms for an automated analysis system in order to understand the structures and connectivity more accurately and automatically [3]. The development of such a system is important as it would help neuroscientists better understand the maps of the partial or the complete brain [4]. To develop such a system, the first step is to find connectomes in the tissue in order to understand the complete connectivity in the brain map. "
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