NEW YORK, USA, August 5, 2008: At the International Symposium on Olfaction and Taste held in San Francisco late last month, Dr. Herz and other researchers discussed the many ways our sense of smell stands alone.
On the one hand, said Jay A. Gottfried of Northwestern University, olfaction is our slow sense, for it depends on messages carried not at the speed of light or of sound, but at the far statelier pace of a bypassing breeze, a pocket of air enriched with the sort of small, volatile molecules that our nasal-based odor receptors can read. Yet olfaction is our quickest sense in evoking reactions. Whereas new signals detected by our eyes and our ears must first be assimilated by a structural way station called the thalamus before reaching the brain’s interpretive regions, odiferous messages go through along dedicated pathways straight from the nose and right into the brain’s olfactory cortex, for instant processing.
The olfactory cortex is embedded within the brain’s limbic system and amygdala, where emotions are born and emotional memories stored. That’s why smells, feelings and memories become so easily and intimately entangled, and why the simple act of washing dishes recently made Dr. Herz’s cousin break down and cry. “The smell of the dish soap reminded her of her grandmother,” said Dr. Herz, author of “The Scent of Desire.”
Many mammals are clearly nosier than we. Consider that our olfactory epithelium, the yellowish mass of mucous membrane located some three inches up from our nostrils, holds about 20 million smell receptors designed to detect odor molecules. The nasal membranes of a bloodhound, by contrast, sustain an olfactory army 220 million receptors strong.
Numerous studies have shown that smell memory is long and resilient, and that the earliest odor associations we make often stick. “With a phone number, if you get a new one, a week later you may have forgotten the old one,” Dr. Herz said. “With smells, it’s the other way around. The first association is better than the second.”
In another presentation, Maria Larsson, an associate professor of psychology at Stockholm University, described the power of smell to serve as an almost magical time machine, with potential for treating dementia, depression, the grim fog of age. Johan Willander and others in her lab have sought to give firm empirical foundation to the idea that smells and aromas, like the famed taste of a madeleine dipped in tea, can help disinter the past.
[HPI note: In ancient Yoga texts, Hindu wisdom long ago associated the sense of smell with memory and the Muladhara chakra.]