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Ralph Greenspan


Dr. Greenspan’s research is broadly concerned with genetic aspects and approaches to studying brain and behavior in Drosophila, informed by the recognition that many of the problems require a systems level approach. One aspect of this is a set of new apparatuses and strategies for recording real-time activity in the brains of behaving flies. The first is a light-field microscopy technique for recording from the entire fly brain at all levels simultaneously. In order to probe more sophisticated tasks while the fly is performing cognitive tasks and record the accompanying brain activity, we use 2-photon recording from the fly brain during a visual attention task. The recordings show activation in specific brain regions that track the formation and duration of the visual memory trace, and its more rapid fading if a distracting stimulus intervenes between stimulus presentation and behavioral testing. In 2011, he was one of the small team of scientists that produced the white paper for the White House Office of Science and Technology Policy that eventuated in the BRAIN Initiative, and in 2014 spearheaded the effort to establish the state-funded Cal-BRAIN program and serves as its Co-Director. In addition to research papers, he has authored: Fly Pushing: The Theory and Practice of Drosophila Genetics, An Introduction to Nervous Systems, and How Genes Influence Behaviour (with Jonathan Flint and Ken Kendler).

Select Publications

  • Grover DH, Chen J-Y, Xie J, Li J, Changeux, JP, Greenspan RJ. (2022) Differential neural mechanisms underlie visual trace and delay conditioning in Drosophila. Feb 16. doi: 10.1038/s41586-022-04433-6. PMID: 35173333.
  • Grover D, Chen J-Y, Xie J, Li J, Changeux J-P, Greenspan RJ. Differential mechanisms underlie trace and delay conditioning in Drosophila. Nature (In press)
  • Shultzaberger RK, Johnson SJ, Wagner J, Ha K, Markow TA, Greenspan RJ. (2019) Conservation of the behavioral and transcriptional response to social experience among Drosophilids. Genes Brain Behav. 18: e12487. PMID: 29797548 DOI: 10.1111/gbb.12487
  • Gold DA, Katsuki T, Li Y, Yan X, Regulski M, Ibberson D, Holstein T, Steele RE, Jacobs DK, Greenspan RJ. (2019) The genome of the jellyfish Aurelia and the evolution of animal complexity. Nat Ecol Evol. 3: 96-104. PMID: 30510179.
  • Grover D, Katsuki T, Li J, Dawkins TJ, Greenspan RJ. (2020) Nat Commun. Imaging brain activity during complex social behaviors in Drosophila with Flyception2. 11: 623-633. PMID: 32001689
  • Aimon S, Katsuki T, Jia T, Grosenick L, Broxton M, Deisseroth K, Sejnowski TJ, Greenspan RJ. (2019) Fast near-whole-brain imaging in adult Drosophila during responses to stimuli and behavior. PLoS Biol. 17: e2006732. PMID: 30768592
  • Wu ST, Chen JY, Martin V, Ng R, Zhang Y, Grover D, Greenspan RJ, Aljadeff J, Su CY. (2022) Valence opponency in peripheral olfactory processing. Proc Natl Acad Sci U S A. 119: e2120134119. PMID: 35091473.
  • Grover D, Chen JY, Xie J, Li J, Changeux JP, Greenspan RJ. (2022) Differential mechanisms underlie trace and delay conditioning in Drosophila. Nature. 603:302-308. PMID: 35173333.


Dr. Ralph J. Greenspan has worked on the genetic basis of behavior and brain function in fruit flies (Drosophila melanogaster) almost since the inception of the field, studying with one of its founders, Jeffery Hall, at Brandeis University in Massachusetts, where he received his Ph.D. in biology in 1979. He is currently Director of the Center for Brain Activity Mapping of the Kavli Institute for Brain and Mind at the University of California San Diego, and Professor in the Division of Biology's Neurobiology Section.

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