In order to understand the connectivity of neuronal networks, their constituent neurons should ideally be studied in a common
framework. Since morphological data from physiologically characterized and stained neurons usually arise from different individual
brains, this can only be performed in a virtual standardized brain that compensates for interindividual variability. The desert
locust,
Schistocerca gregaria, is an insect species used widely for the analysis of olfactory and visual signal processing, endocrine functions, and neural
networks controlling motor output. To provide a common multi-user platform for neural circuit analysis in the brain of this
species, we have generated a standardized three-dimensional brain of this locust. Serial confocal images from whole-mount
locust brains were used to reconstruct 34 neuropil areas in ten brains. For standardization, we compared two different methods:
an iterative shape-averaging (ISA) procedure by using affine transformations followed by iterative nonrigid registrations,
and the Virtual Insect Brain (VIB) protocol by using global and local rigid transformations followed by local nonrigid transformations.
Both methods generated a standard brain, but for different applications. Whereas the VIB technique was designed to visualize
anatomical variability between the input brains, the purpose of the ISA method was the opposite, i.e., to remove this variability.
A novel individually labeled neuron, connecting the lobula to the midbrain and deutocerebrum, has been registered into the
ISA atlas and demonstrates its usefulness and accuracy for future analysis of neural networks. The locust standard brain is
accessible at
http://www.3d-insectbrain.com.
Keywords Virtual Insect Brain protocol - Iterative shape-averaging - Three-dimensional reconstruction - Standard brain - Virtual neuroanatomy -
Schistocerca gregaria (Insecta)
This work was supported by the Deutsche Forschungsgemeinschaft (U. Homberg; HO 950/14-3) and the National Institute on Alcohol
Abuse and Alcoholism (T. Rohlfing; AA05965 and AA13521).