If you know even a little about the olfactory system, you get the general idea that at the very beginning of any perceptible smell are numerous events in which odorous molecules bind to receptor proteins. This ultimately results in a neural signal being transmitted into the brain via the olfactory bulb. This was my starting point, too, but I decided it would be interesting to know how all that actually happened.
A universal truth that keeps popping up in my search of the literature is that nothing is as simple as it seems. A sniff seems just a simple movement of air, but it’s actually way more than that: it’s a psychomotor event. One crucial function is to synchronize the olfactory receptor cells with the olfactory bulb and other smell-related brain regions, especially the primary olfactory processing center, the piriform cortex. This allows different regions to communicate with each other…
Beer is more complex than any other beverage known. No one’s keeping the master list of odor chemicals, but it’s huge. Hops alone contain more than 1000 terpenoids with citrus, floral and other aromas, with many other chemicals, too. In malt, Maillard and other browning processes create hundreds more. Fermentation and subsequent maturation creates a third enormous family of aromas, yet there are more. Add them all up and you get far in excess of the widely quoted number of 600–1000 odor chemicals in wine.