How does odor concentration change the strength of a smell signal sent to the brain?

In the olfactory system, the strength of a smell signal sent to the brain is directly influenced by the concentration of odor molecules present. As the concentration of an odorant increases, two primary physiological events occur:

• Increased Receptor Occupancy: A higher number of receptor molecules within individual olfactory cells become bound by odorant molecules at the same time.
• Recruitment of Cells: A larger total number of olfactory receptor cells are stimulated.

These combined effects lead to the generation of more action potentials (nerve impulses) across a greater number of receptor cells. Consequently, the cumulative signal transmitted to the brain is strengthened, which is why a scent may be perceived as ranging from barely perceptible to overpowering depending on its concentration.1