Feature extraction from mixed odor stimuli based on spatio-temporal representation of odors in olfactory bulb

In order to clarify the neural mechanism by which olfactory features are extracted from mixed odor stimuli, we present a model in which each constituent molecule of odor is encoded into a spatial firing pattern in the olfactory bulb and the order of mixing ratio of the molecule is coded into the order of temporal sequence of the spatial patterns. That is, quality and intensity of each odor are encoded into a limit cycle attractor in the dynamical network of olfactory bulb. It depends on types of temporal fluctuation of constituent odor intensity what kinds of limit cycle attractors are formed under application of mixed odor stimulation. When the fluctuation of each odor in the mixture is independent of those of the other odors, each odor is encoded separately into each attractor. However, some odors with coherent fluctuation are encoded into a single limit cycle attractor, that is, recognized as a single feature