Learned odor discrimination in Drosophila without combinatorial odor maps in the antennal lobe.

Journal article

A unifying feature of mammalian and insect olfactory systems is that olfactory sensory neurons (OSNs) expressing the same unique odorant-receptor gene converge onto the same glomeruli in the brain [1-7]. Most odorants activate a combination of receptors and thus distinct patterns of glomeruli, forming a proposed combinatorial spatial code that could support discrimination between a large number of odorants [8-11]. OSNs also exhibit odor-evoked responses with complex temporal dynamics [11], but the contribution of this activity to behavioral odor discrimination has received little attention [12]. Here, we investigated the importance of spatial encoding in the relatively simple Drosophila antennal lobe. We show that Drosophila can learn to discriminate between two odorants with one functional class of Or83b-expressing OSNs. Furthermore, these flies encode one odorant from a mixture and cross-adapt to odorants that activate the relevant OSN class, demonstrating that they discriminate odorants by using the same OSNs. Lastly, flies with a single class of Or83b-expressing OSNs recognize a specific odorant across a range of concentration, indicating that they encode odorant identity. Therefore, flies can distinguish odorants without discrete spatial codes in the antennal lobe, implying an important role for odorant-evoked temporal dynamics in behavioral odorant discrimination.

Authors: Dasgupta, S; Waddell, S

• Journal: Current biology : CB
• Volume: 18
• Issue: 21
• Pages: 1668-1674
• Publication date: 2008-11-01
• DOI: 10.1016/j.cub.2008.08.071
• EISSN: 1879-0445
• ISSN: 0960-9822
• Language: English
• Keywords: Olfactory Perception; Brain; Animals; Discrimination Learning; Olfactory Receptor Neurons; Drosophila Proteins; Drosophila; Receptors, Odorant