the same places, making identical synaptic connections in every worm. Brenner's team sliced worms into thousands of ultrathin sections and photographed every section under an electron microscope, then visually matched fibers from section to section, to map out every neuron and synapse in the entire body, to give a complete connectome of the nematode. Nothing approaching this level of detail is available for any other organism, and the information has been used to enable a multitude of studies that would not have been possible without it. Drosophila melanogaster Drosophila melanogaster is a popular experimental animal because it is easily cultured en masse from the wild, has a short generation time, and mutant animals are readily obtainable. Arthropods have a central brain with three divisions and large optical lobes behind each eye for visual processing. The brain of a fruit fly contains several million synapses, compared to at least 100 billion in the human brain. Approximately two-thirds of the Drosophila brain is dedicated to visual processing. Thomas Hunt Morgan started to work with Drosophila in 1906, and this work earned him the 1933 Nobel Prize in Medicine for identifying chromosomes as the vector of inheritance for genes. Because of the large array of tools available for studying Drosophila genetics, they have been a natural subject for studying the role of genes in the nervous system. The genome has been sequenced and published in 2000. About 75% of known human disease genes have a recognizable match in the genome of fruit flies. Drosophila is being used as a genetic model for several human neurological diseases including the neurodegenerative disorders Parkinson's, Huntington's, spinocerebellar ataxia and Alzheimer's disease. In spite of the large evolutionary distance between insects and mammals, many basic aspects of Drosophila neurogenetics have turned out to be relevant to humans. For instance, the first biological clock genes were identified by examining Drosophila mutants that showed disrupted daily activity cycles. See also Connectogram Outline of the human brain Outline of brain mapping List of regions in the human brain Medical image computing Neurology Neuroscience Computational anatomy Citations Sources External links Neuroanatomy, an annual journal of clinical neuroanatomy Mouse, Rat, Primate and Human Brain Atlases (UCLA Center for Computational Biology) brainmaps.org: High-Resolution Neuroanatomically-Annotated Brain Atlases BrainInfo for Neuroanatomy Brain Architecture Management System, several atlases of brain anatomy White Matter Atlas, Diffusion Tensor Imaging Atlas of the Brain's White Matter Tracts Nervous system