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Statistical Mechanics in Systems Biology: Villa Orlandi, Anacapri ~ May 29 - June 1, 2012 |
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Thierry Emonet Dept of Molecular Cellular and Developmental Biology and Dept of Physics, Yale University, New Haven, CT (USA) Temporal features of odor stimuli and the encoding of odor identity and intensity by Olfactory Receptor Neurons Odor stimuli are detected by Olfactory Receptor Neurons (ORNs) that project to segregated regions of the brain called glomeruli, where they make synaptic connections with second-order neurons. Different odorants elicit distinct patterns of activity in the population of ORNs as well as in the glomeruli, suggesting that odors are encoded in spatial combinatorial maps. Odors also elicit diverse temporal patterns of activity at several levels of the olfactory system but their origin and role in odor coding remains so far unclear. We performed single sensillum recordings from the Drosophila antenna simultaneously with measurements of the odorant concentration reaching the fly. We found that in several conditions stimulus dynamics depends on odor type before any interaction with the olfactory system occurs. Individual ORNs follow these differences in stimulus dynamics with such precision that a linear-nonlinear model can predict the response of one ORN to different odorants solely from measurements of the stimulus. This suggests that a single response function can be associated to a single ORN and mediates the response to a large set of different odors. Importantly we found that ORN adaptation capabilities maintain response dynamics remarkably similar across a large range of stimulus and background intensities. Hence, irrespective of the odor and receptor type, ORNs can capture information about stimulus dynamics independently from the intensity of the signal. Our results open the question of whether odor-specific dynamics might be used in discrimination tasks and affect odor tracking strategies. |
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