期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2009
卷号：106
期号：46
页码：19219-19226
DOI：10.1073/pnas.0910592106
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：With Manduca sexta as a model system, we analyzed how natural odor mixtures that are most effective in eliciting flight and foraging behaviors are encoded in the primary olfactory center in the brain, the antennal lobe. We used gas chromatography coupled with multiunit neural-ensemble recording to identify key odorants from flowers of two important nectar resources, the desert plants Datura wrightii and Agave palmeri, that elicited responses from individual antennal-lobe neurons. Neural-ensemble responses to the A. palmeri floral scent, comprising >60 odorants, could be reproduced by stimulation with a mixture of six of its constituents that had behavioral effectiveness equivalent to that of the complete scent. Likewise, a mixture of three floral volatiles from D. wrightii elicited normal flight and feeding behaviors. By recording responses of neural ensembles to mixtures of varying behavioral effectiveness, we analyzed the coding of behaviorally "meaningful" odors. We considered four possible ensemble-coding mechanisms--mean firing rate, mean instantaneous firing rate, pattern of synchronous ensemble firing, and total net synchrony of firing--and found that mean firing rate and the pattern of ensemble synchrony were best correlated with behavior (R = 41% and 43%, respectively). Stepwise regression analysis showed that net synchrony and mean instantaneous firing rate contributed little to the variation in the behavioral results. We conclude that a combination of mean-rate coding and synchrony of firing of antennal-lobe neurons underlies generalization among related, behaviorally effective floral mixtures while maintaining sufficient contrast for discrimination of distinct scents.
