Making Sense of Scents: Why Odors Spark Memory

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Wendy Suzuki is a professor of neural science and psychology in the Center for Neural Science at New York University (NYU). A popular speaker, she is a regular presenter at the World Science Festival and TEDx, and is frequently interviewed on television and in print for her expertise regarding the effects of exercise on brain function. Her first book, "Healthy Brain, Happy Life" (Dey Street Books, 2015), will be released in May. Suzuki contributed this article to Live Science's Expert Voices: Op-Ed & Insights

While vision is arguably the sense scientists have studied the longest and most deeply, the human sense of smell is more complicated, more ancient, and more difficult to describe and observe. But science's understanding of olfaction, the sense of smell, is finally starting to catch up to the science of vision, particularly following the work of neuroscientists Linda Buck of the Fred Hutchinson Cancer Research Center and Richard Axel of Columbia University.

In 1991, Buck and Axel were the first to identify the genes that encode the odorant (smell) receptors in the brain. Receptors can be thought of as the specialized "doors" or "entryways" into brain cells that give particular substances, like the chemicals that make up odors, access to the inner workings of olfactory brain cells. That discovery sparked a renaissance of research into the sense of smell , and Buck and Axel won the Nobel Prize for their work in 2004.

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The new understanding of the sense of smell, focusing on those key olfactory receptors , is arguably one of the hottest areas of sensory neuroscience research today. Yet the science of smell goes far beyond just an understanding of the olfactory receptors. It is a fascinating and mysterious sense that contains many areas to explore, including the powerful link between the sense of smell and evocative emotional memories.

Everyone has had that experience of catching a chance whiff of an odor that transports you back to a very specific time and place in your life. For me, it happened when returning to Lake Tahoe, California, for a conference a few years ago. One deep breath of that crisp mountain air, tinged with that tiny bit of propane, immediately transported me back to lazy summer camping vacations with my family in the woods around that lake. I could feel what it was like to lay in the sun on big rocks by the water, and the delectable flavor of campfire-roasted marshmallows in the evenings.

For my latest episode of Totally Cerebral (part of the Transistor series) called "What’s That Smell?," I wanted to explore the emotional underbelly of people's sense of smell. So I reached out to renowned colleagues, including neuroscientist Howard Eichenbaum, who is an expert on olfactory memory at Boston University; executive chef Anita Lo of Annisa restaurant in New York City; and NYU chemist Kent Kirshenbaum, the co-founder of the university's experimental cuisine collective.

Anatomically, Eichenbaum explained, the olfactory system has unique connections with two key regions in the brain's temporal lobe: the hippocampus, which is critical for laying down new long-term memories, and the amygdala, critical for processing emotions. Unlike all the other senses (i.e., vision, touch and hearing), which require many connections — synapses — to reach the hippocampus and amygdala, olfactory information has immediate access to those systems. It therefore has the ability to lay down long-lasting memories linked to particular times and places (a specialty of the hippocampus) and to include deep emotional resonance associated with those memories (processed by the amygdala).

For a different perspective on the importance of the sense of smell, Kirshenbaum and I talk to Lo at her restaurant. We get the chance to eat some of her award-winning dishes, and Lo talks about how she plays with the power of smell to evoke emotion and memory. Through food, sense of smell plays an essential part in some of the most pleasurable parts of people's everyday lives. Because food so often works to bring people pleasure and connection with each other, this makes the sense of smell an even more powerful tool to evoke the memories of key, food-centered pleasures in people's lives.