Odor-background segregation of unknown odorants based on stimulus onset asynchrony in honey bees

Animals use olfaction to search for distant objects. Unlike vision, where objects are spaced out, olfactory information mixes when it reaches olfactory organs. Therefore, efficient olfactory search requires segregating odors that are mixed with background odors. Animals can segregate known target odors by detecting short differences in the arrival of odorants from different sources (stimulus onset asynchrony). However, it is unclear whether animals can also use stimulus onset asynchrony to segregate previously unknown odorants that have no innate or learned relevance. Using behavioral experiments in honey bees, we here show that stimulus onset asynchrony also improves odor-background segregation of unknown odorants. The stimulus onset asynchrony necessary to behaviorally segregate unknown odorants is in the range of seconds, which is two orders of magnitude larger than the previously reported stimulus asynchrony sufficient for segregating known odorants. We propose that for unknown odorants, odor-background segregation requires sensory adaptation to the background stimulus.