Olfaction

It has been hypothesized that the brain uses combinatorial as well as temporal coding strategies to represent stimulus properties. The mechanisms and properties of the temporal coding remain undetermined, although it has been postulated that oscillations can mediate formation of this type of code. We use a generic model of the vertebrate olfactory bulb to explore the possible role of oscillatory behavior in temporal coding. A number of mechanisms, including synaptic inhibition, slow self-inhibition and input strength, mediate formation of a temporal sequence associated with specific odorants within the oscillatory response. The sequence formed depends on the relative properties of odorant features and thus may mediate discrimination of odorants activating overlapping sets of glomeruli. Modeling results also suggest that period doubling transitions may be driven through excitatory feedback from a portion of the olfactory network acting as a coincidence modulator.