Drosophila connectome
The Drosophila connectome, once completed, will be a complete list of the roughly 135,000 neurons in the brain of the fruit fly Drosophila melanogaster, along with all of the connections (synapses) between these neurons. As of 2013, the Drosophila connectome is a work in progress, being obtained by the methods of neural circuit reconstruction. Portions of two of the 76 compartments of the Drosophila brain have connectomes available, and others are subjects of ongoing study.
Why Drosophila
Connectome research (connectomics) has a number of competing objectives. On the one hand, investigators prefer an organism small enough that the connectome can be obtained in a reasonable amount of time. This argues for a small creature. On the other hand, one of the main uses of a connectome is to relate structure and behavior, so an animal with a large behavioral repertoire is desirable. It's also very helpful to use an animal with a large existing community of experimentalists, and many available genetic tools. Drosophila looks very good on these counts:
- The brain contains about 135,000 neurons,[1] small enough to be reconstructed in the near future.
- The fruit fly exhibits many complex behaviors. Hundreds of different behaviors (feeding, grooming, flying, mating, learning, and so on) have been qualitatively and quantitatively studied over the years.
- The genetics of the fruit fly are well understood, and many (tens of thousands) of genetic variants are available.
- There are many electrophysiology, calcium imaging, and other studies ongoing with Drosophila.
Current status
A high-level connectome, at the level of brain compartments and interconnecting tracts of neurons, exists for the full fly brain.[2] A version of this is available online.[3]
Detailed circuit-level connectomes exist for the lamina[4][5] and a medulla[6] column, both in the visual system of the fruit fly.
References
- ↑ Alivisatos, A Paul and Chun, Miyoung and Church, George M and Greenspan, Ralph J and Roukes, Michael L and Yuste, Rafael (2012). "The brain activity map project and the challenge of functional connectomics" (PDF). Neuron. Elsevier. 74 (6): 970–974. doi:10.1016/j.neuron.2012.06.006. PMC 3597383
. PMID 22726828. - ↑ Chiang, Ann-Shyn and Lin, Chih-Yung and Chuang, Chao-Chun and Chang, Hsiu-Ming and Hsieh, Chang-Huain and Yeh, Chang-Wei and Shih, Chi-Tin and Wu, Jian-Jheng and Wang, Guo-Tzau and Chen, Yung-Chang; et al. (2011). "Three-Dimensional Reconstruction of Brain-wide Wiring Networks in Drosophila at Single-Cell Resolution". Current Biology. Elsevier. 21 (1): 1–11. doi:10.1016/j.cub.2010.11.056.
- ↑ "FlyCircuit - A Database of Drosophila Brain Neurons". Retrieved 30 Aug 2013.
- ↑ Meinertzhagen, IA; O'Neil, SD (1991). "Synaptic organization of columnar elements in the lamina of the wild type in Drosophila melanogaster". Journal of comparative neurology. Wiley Online Library. 305 (2): 232–263. doi:10.1002/cne.903050206. PMID 1902848.
- ↑ Rivera-Alba, Marta and Vitaladevuni, Shiv N and Mishchenko, Yuriy and Lu, Zhiyuan and Takemura, Shin-ya and Scheffer, Lou and Meinertzhagen, Ian A and Chklovskii, Dmitri B and de Polavieja, Gonzalo G (2011). "Wiring Economy and Volume Exclusion Determine Neuronal Placement in the Drosophila Brain". Current Biology. 21 (23): 2000–2005. doi:10.1016/j.cub.2011.10.022.
- ↑ Shin-ya Takemura; Arjun Bharioke; Zhiyuan Lu; Aljoscha Nern; Shiv Vitaladevuni; Patricia K. Rivlin; William T. Katz; Donald J. Olbris; Stephen M. Plaza; Philip Winston; Ting Zhao; Jane Anne Horne; Richard D. Fetter; Satoko Takemura; Katerina Blazek; Lei-Ann Chang; Omotara Ogundeyi; Mathew A. Saunders; Victor Shapiro; Christopher Sigmund; Gerald M. Rubin; Louis K. Scheffer; Ian A. Meinertzhagen; Dmitri B. Chklovskii (8 August 2013). "A visual motion detection circuit suggested by Drosophila connectomics". Nature. 500 (7461): 175–181. doi:10.1038/nature12450.