The computational rules followed by the brain to encode complex, multi
dimensional stimuli such as natural odors are not well understood. In
this review, we summarize results obtained in the olfactory system of
an insect and present a hypothesis for odor representation in the brai
n. We propose that individual odors are represented by ensembles of ne
urons that are distributed both in space (the specific identities of t
he neurons forming an ensemble) and in lime (the time at which each ne
uron participates in the ensemble response), In addition, we discuss t
he potential roles that periodic synchronization (oscillations) might
play in this complex process.