A pivotal area of neuroscience is to understand how sensory information from the external environment is received, processed, and interpreted by the brain. For example, why does an apple smell like an apple, and an orange like an orange? Our ability to ‘smell’ different odors is tightly linked to our sense of odor perception. Yet little is known about how odor perception is processed in the brain.
The primary goal of the lab is to characterize the anatomy, development, and function of neurons required for olfactory behaviors in Drosophila. Our initial focus is on the projection neurons (mitral/tufted cells in mammals) that connect the antennal lobe to the higher order regions of the fly brain such as the mushroom bodies and lateral horn (See Figure). We first carried out an exhaustive study of PN anatomy with the logic that their stereotyped axonal projections might underlie biological functions. Indeed, we found that ‘fruity odors’, which represent food, and pheromones, which represent sex, signal to distinct regions of the lateral horn. This organization was further respected by lateral horn output neurons. They too showed specificity to either the ‘fruity’ or ‘sex’ regions of the lateral horn. Therefore, the lateral horn region, which to the naked eye looks quite homogeneous, might actually be organized into subdomains according to the biological meanings of the stimuli.
By using neurogenetics, we can label and manipulate small populations of neurons and assay their effects on olfactory behaviors. Such detailed genetic perturbations are possible using the ‘Q-system’ we have developed: a repressible binary expression system, that when used in combination with the GAL4 system, allows for genetic silencing or activation of small neuronal populations. We have also developed a high throughput computer controlled olfactory attraction and repulsion assay. In this assay, hundreds of flies can be tracked simultaneously as they respond to different odorants at many carefully controlled odorant concentrations. From such analyses, we can effectively and efficiently link precisely defined neuronal populations to their respective odorant behaviors.
Current projects in the lab involve:
1) characterizing the function of the projection neurons in relaying odorant information to higher brain centers.
2) characterizing the adult fly’s olfactory system in eliciting stereotyped attractive or repulsive behaviors to discrete odorants.
3) identifying and characterizing additional neuronal circuitry required for olfactory behaviors.
4) developing additional genetic tools for linking neurons to their function.
For more information, please visit our lab site.
Wei X Potter CJ, Luo L, and Shen K. (2012) Controlling Gene Expression with the Q Repressible Binary Expression System in Caenorhabditis elegans. Nat Methods 9:391-395.
Sweeney LB, Chou YH, Wu Z, Joo W, Komiyama T, Potter CJ, Kolodkin AL, Garcia KC, and Luo L. (2011) Secreted Semaphorins from Degenerating Larval ORN Axons Direct Adult Projection Neuron Dendrite Targeting. Neuron 72: 734-747.
Potter CJ and Luo L. (2011) Using the Q system in Drosophila melanogaster. Nat. Protocols 6:1105-1120.
Gohl DM, Silies MA, Gao XJ, Bhalerao S, Luongo FJ, Lin CC, Potter CJ, and Clandinin TR. (2011) A Genetically Convertible Enhancer Trap Platform For Directed Combinatorial Dissection Of Gene Expression Patterns. Nat Methods 8(3):231-237.
, Tasic B*, Russler EV, Liang L, and Luo L. (2010) The Q System: A Repressible Binary Expression System for Transgene Expression, Lineage Tracing and Mosaic Analysis. Cell 141:536-548. *Denotes equal contribution. PubMed Reference
Potter,CJ and Luo L. (2010) Splinkerette PCR for Mapping Transposable Elements in Drosophila. PLoS ONE 5(4):e10168.
Hong W, Zhu H, Potter CJ, Barsh G, Kurusu M, Zinn K, and Luo L. (2009) Leucine-rich repeat transmembrane proteins instruct discrete dendrite targeting in an olfactory map. Nature Neuroscience, 12:1542-1550.
Berdnik D, Fan AP, Potter CJ
and Luo L. (2008) microRNA Processing Pathway Regulates Olfactory Neuron Targeting. Current Biology 18:1754-9. PubMed Reference
Potter CJ and Luo L. (2008) Octopamine Fuels Fighting Flies. Nature Neuroscience 11:989-90.
Jefferis GSXE*, Potter,CJ*, Chan AM, Marin EC, Rohlfing T, Maurer CR, Jr, and Liqun L. (2007) Comprehensive Maps of Drosophila Higher Olfactory Centers: Spatially Segregated Fruit and Pheromone Representation. Cell, 128:1187-1203. *Denotes equal contribution.