The olfactory system in insects has evolved to process the dynamic changes in the concentration of food odors or sex pheromones to localize the nutrients or conspecific mating partners. Experimental studies have suggested that projection neurons (PNs) in insects encode not only the stimulus intensity but also its rate-of-change (input gradient). In this study, we aim to develop a simple computational model for a PN to understand the mechanism underlying the coding of the rate-of-change information. We show that the spike frequency adaptation is a potential key mechanism for reproducing the phasic response pattern of the PN in Drosophila. We also demonstrate that this adaptation mechanism enables the PN to encode the rate-of-change of the input firing rate. Finally, our model predicts that the PN exhibits the intensity-invariant response for the pulse and ramp odor stimulus. These results suggest that the developed model is useful for investigating the coding principle underlying olfactory information processing in insects.

Graduate School of Frontier Sciences The University of Tokyo Kashiwa 277 8561 Japan; Mathematics and Informatics Center The University of Tokyo Tokyo 113 8656 Japan; JST PRESTO Saitama 332 0012 Japan

Institute of Physiology Czech Academy of Sciences Prague 142 20 Czech Republic

Research Center for Advanced Science and Technology The University of Tokyo Tokyo 153 8904 Japan

School of Engineering The University of Tokyo Tokyo 113 8656 Japan

Citace poskytuje Crossref.org