Abstract
To understand the human brain is a difficult task, because of its enormous number of neuron. In basic research of life science, a fruit fly, Drosophila melanogaster, with the abilities of learning and memory is chosen for research to facilitate the understanding of structures and functions of the brain. With the advent of fluorescent proteins, molecular biological techniques and the advanced confocal microscopy, it is now possible to visualize the expression of genes even in single cells. In the neurobiology of Drosophila, a standard for brain anatomy is necessary. Since there are more than thousands of genes expressed in the Drosophila brain, there is no way to observe all of them in a single tissue. A complete genetic map of the neural networks can only be achieved by warping individual gene expression images into a common coordinate system, a standard framework of the Drosophila brain. We propose a Drosophila brain atlas, also called the Drosophila standard brain, for serving as a common coordinate system in the neurobiology of Drosophila. It is constructed from confocal microscopy scans of individual Drosophila brains. We obtain the individual brain model by first acquiring the confocal microscopy raw images and following an image processing procedure for segmentation and 3-D reconstruction. Combining all these individual brain models and applying the general averaging procedure, we can finally generate the standard brain model. The Drosophila standard brain comprises the standard cortex (the average-shape cortex) and the standard neuropils (the average-shape neuropils). The standard neuropils are located within the standard cortex with the average positions and orientations. Compared with arbitrarily selected templates, the standard template can give smaller average disparity to the individual Drosophila brains and consequently lead to a better warping result.