The people who have the best olfactory vocabularies are those who use their nose to make a living: wine critics, perfume designers, and the like. These experts, too, tend to name odors by connecting them to things with a similar smell (perhaps that Bordeaux was redolent of graphite, black currents, and camphor?). Their descriptions don’t always translate for the rest of us, especially when they reach for abstract terms. When Parker identifies a wine as “austere,” “brawny,” or “decadent,” do you know what he means? (If you think you do, try a blind taste test).
At Northwestern, Gottfried has been studying people at the other end of the spectrum, patients with a type of dementia called primary progressive aphasia, who are especially bad at naming smells. Unlike people with Alzheimer’s disease, their problems involve language more than memory.
These patients were just abysmal at naming common odors like rose, onion, and gasoline, getting it right only about 23 percent of the time, compared to 58 percent accuracy for a group of control subjects, Gottfried and colleagues reported last year in Brain. However, when the researchers gave the same aphasia patients a list of four odor names to choose from, they performed nearly as well as controls. That suggests to Gottfried that a) their sense of smell is intact, and b) they know the right words despite their aphasia. Rather, he says, it must be the connections between the olfactory and language parts of the brain that are impaired.
That study also had a brain imaging component: using MRI scans, the researchers found that the people with the biggest odor-naming deficit tended to have damage to the anterior pole of the frontal lobe. A human brain viewed from the side looks a little like a mitten; this region would be the tip of the thumb.