Fig. 1.

Hypothesis: Ephaptic inhibition is sensitive to relative stimulus timing and aids odor source discrimination. In a sensillum (a), co-localized ORNs inhibit each other’s response via ephaptic inhibition. Most natural odor stimuli are transient and fluctuate as a result of dispersion in turbulent plumes in the air. Different odorants (A and B) from a single source (b) arrive synchronously at olfactory receptor neurons (ORN) (c), making the odorant mixture’s neural representation different from the sum of its parts A and B (d). Odorants (A and B) from different sources (e) arrive asynchronously at the ORNs (f). Since ephaptic inhibition is active when the affected ORN exhibits weak or no response, it affects the neural responses less (g). This results in the neural representation of the odorant mixture resembling the sum of its individual components, A and B. Data in (b) and (e) from (Kree et al. 2013), data in (c), (d), (f), and (g) is fabricated.