Caenorhabditis elegans (C. elegans) is a 1-1.5mm-long nematode that lives in soil and feeds on bacteria such as Escherichia coli (E. coli). Most C. elegans are hermaphrodites, or self-fertilizing. C. elegans is a popular model organism in a variety of biological research due to its short lifespan, its ability to self-reproduce, and its small size. Additionally, its translucent body enables easy visualization of cells tagged with fluorescent proteins. For neuroscience research in particular, C. elegans is a favored model because it is the first animal to have its entire genome sequenced. The adult hermaphrodite C. elegans has 302 neurons, and the connectome of the C. elegans nervous system has been extensively documented and is widely available in databases such as Wormbook and OpenWorm.

Caenorhabditis elegans (C. elegans)

Rodents are the most widely used model organism in neuroscience and biomedical research. Rats and mice differ significantly in gene expression, social behaviors, and physiology, giving them unique advantages and disadvantages as the favorable model in any particular research. For example, mice were more commonly used due to their larger “genetic toolbox,” which includes transgenic and “knockout”/”knock-in” mice. However, adult rats typically weigh up to ten times more than adult mice. Their larger size makes surgery and other invasive procedures such as catheter insertion easier to perform, while mice are chosen for optogenetics experiments because light passes more easily through their smaller brains and can therefore reach deeper regions of the brain.

Rodentia (mouse, rat)

 Drosophila melanogaster (fruit flies) are valuable model organisms for studying mechanisms underlying development and human disease. Like C. elegans, Drosophila are favored models due to their short generation time, high rate of reproduction, and convenient maintenance within the laboratory. Around 65% of genes that cause disease in humans have functional homologs in flies, and 38 of 59 human neurological genes have orthologs in flies. Additionally, the Drosophila genome has been fully sequenced, allowing for more precision when manipulating genes.

Drosophila melanogaster (fruit fly)

Astatotilapia burtoni (A. burtoni) is a cichlid fish native to East Africa. Male A. burtoni are separated by a defined social hierarchy, in which dominant males defend territory and court females, while subordinate males shoal with other subordinate males. A. burtoni are a desirable model system for studying social behaviors (e.g. aggression) and social plasticity.

Astatotilapia burtoni (A. burtoni)

- Caenorhabditis elegans (roundworm)
- Drosophila melanogaster (fruit fly)
- Astatotilapia burtoni (cichlid fish)
- Danio rerio (zebrafish)
- Xenopus laevis (frog)
- Rodentia (mouse, rat)

Pomona College

Many breakthroughs in neuroanatomy and neurophysiology were discovered via animal models. Both vertebrates and invertebrates provide simplistic but convenient models for the mechanisms of the human nervous system. Romanova and Sweedler (2018) highlight six model organisms that have contributed to our current understanding of neuroscience.

Model Organisms in Neuroscience

Romanova, E. V., & Sweedler, J. V. (2018). Animal Model Systems in Neuroscience. ACS Chemical Neuroscience, 9(8), 1869–1870. https://doi.org/10.1021/acschemneuro.8b00380

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