Sniff Olfactometry: Temporal effects on odorant mixture perception in humans

There is evidence in mice and honeybees that signals initiated by odorants at the olfactory epithelium arrive downstream in the olfactory bulb between 10 and 200ms later and that these latencies are ligand dependent. It has recently been proposed that these latencies could be used by mice to identify or classify. Here we demonstrate that humans are sensitive to the timing of individual of odorant presentation. Using a two-alternate forced choice (2AFC) paradigm—subjects chose which odorant they recognized first after they experienced two 70ms puffs separated in time by some interval in the range of -450ms to +450ms. All subject recognition probabilities yielded the same linear function of latency (p<0.05) even though they differed in their recognition thresholds for the components and their recognition probability to detect them in binary mixtures. These results indicate that temporal structure of odor delivery affects human odor perception and sniff olfactometry (SO) has the temporal resolution necessary to measure these effects.