A novel multicomponent stimulus device for use in olfactory experiments

Olfactory studies have expanded beyond the study of single compound odor perception to explore the processing of complex mixtures and blends. The spatiotemporal presentation of blend stimuli is a challenging task requiring volatiles with diverse chemical and physical properties to be presented as a unified stimulus. This not only necessitates accurate control of the timing and homogeneity of the odor stream, but requires attention to the concentration of each blend component presented. We have developed a novel, multicomponent stimulus system for use in olfactory experiments that is capable of presenting up to 8 different odors simultaneously or in sequence at defined concentrations and time scales. Each odor is separated to minimize physical or chemical interactions, and stimulations are performed from a saturated headspace of the odor solution. Stimulus concentrations can be measured empirically or estimated using common gas laws. Photoionization detector measurements show that stimuli could be presented as cohesive blends or single components at frequencies of at least 10 Hz without leakage or contamination. Solid phase microextraction measurements also show that the concentration of each component could be equilibrated through regulation of each component line's flow rate based on the different partial vapor pressures of the odorants. This device provides a unique method for introducing complex volatile mixtures for olfactory studies in a variety of animal taxa and allows for accurate control of odor intensities in both time and space.

Research highlights▶ Development of a multicomponent stimulus system capable of presenting up to 8 odors. ▶ Components can be presented separately or simultaneously as a unified odor pulse. ▶ Stimulus pulses are separated at frequencies of at least 10 Hz with little bleed or contamination. ▶ Component concentrations are regulated according to odorant partial vapor pressures. ▶ Device is suitable for a variety of olfactory tasks such as behavior, electrophysiology, or functional imaging.