Read: how a smell travels from nose to memory

Okay, nerd moment: I finally read the Wikipedia article on the sense of smell properly.

Smell molecules bind to receptors on nerve cells in the lining of the nose, the signal passes through the olfactory bulb, and from there it reaches the parts of the brain that handle memory and emotion, the amygdala and the hippocampus among them. Mammals have about 1,000 genes for smell receptors, and humans actually have fewer working ones. Buck and Axel got the 2004 Nobel Prize for cloning those receptors. Rant over.