Remembering Smell (18 page)

Spring was coming and with it the lilacs. Lilac time. The word alone—
lilacs
—brought visions of springs past. But no fragrance. I was again reminded that smell differs from hearing and sight in that it cannot be remembered. You can dredge up a tune or picture a long-lost loved one's face, but you can't conjure a scent out of whole cloth, even with the help of a memory. I would never smell spring again, even in my mind's eye.

I
N
Speak, Memory,
Vladimir Nabokov wrote that "nothing is sweeter or stranger than to ponder those first thrills [of childhood]." He remembered how he chewed a corner of a bed sheet "until it was thoroughly soaked" and then wrapped a candy Easter egg in it tightly "so as to admire and re-lick the warm, ruddy glitter of the snugly enveloped facets that came seeping through." Such recollections are unimpeachable, he concluded, because they "possess a naturally plastic form in one's memory which can be set down with hardly any effort." Memories are more elusive if they lack corroboration by all the senses, especially the sense of smell. Without it, "I have to go by comets and eclipses, as historians do when they tackle the fragments of a saga."

Moments lost in a book were still rare as winter wore on. And it would be a long while before a book could put me to sleep. Sometimes I would give up on reading. One night after Cam had fallen asleep I made my way like a sleepwalker, or like one of those ghoulish zombies in a horror film, to my attic office. I turned on the computer and opened a folder on my desktop where I kept pictures of my garden. Minnesota winters are so long, you forget what summer looks like.

The first photo was of my back porch. I'd trained the fragrant American Beauty rose to a trellis on one of the posts, along with several other aromatic vines. The idea was to create an olfactory symphony—composed of notes, just the way perfumers did it—with roses and wisteria as the high and middle floral notes and herbs as the less feminine but zestier and longer-lasting low notes. The potted herbs sat in three rows on the porch steps, like a family having their picture taken. There was the prim mother (a scented geranium on a standard), the paunchy dad (sweet basil in a round ceramic planter), the gaggle of unruly kids (mint, mint, and more mint), the gnarled grandparents (sage and rosemary). There were various aunts and uncles too: lemon oregano, French tarragon, English lavender, and thyme. I had been thinking (then) of sending this out as a Christmas card.

While reading fiction remained difficult, I continued to devour science papers. It was comforting to read that science was trying to cure emotional problems caused by life-changing trauma. Any scientifically proven connection between smell and mood got my attention. I'd read somewhere that sniffing helped lift subconscious smells locked in memory to the level of consciousness. Did one need a working nose for that?

Scientists like Richard Axel call smell the primal sense because of its primary importance to survival in ancient species. In conjunction with the fear response (fight or flight) it was the first line of defense against predators. This role seems to have made the oldest parts of the brain the most stable and resilient; the olfactory cells are the only neurons that repair themselves, and smell is the most unerring of the senses when it comes to attaching an emotion (first and foremost is fear) to an event. This attachment is so strong that the original event is the one most likely to rise from the depths of submerged long-term memory to conscious awareness on the strength of a whiff of an odor. No subsequent event associated with the smell is as quick to present itself as the first one. The emotional power of the event, whether positive or negative, also influences smell's effectiveness as a trigger. First the nose evaluates whether a smell is a threat, based on experience, and then sends an action message (such as fight or flight) to the rest of the limbic system; only then does the mind register the odor's name. In all these ways smell differs from the newer senses of sight and hearing. Rachel Herz thinks humans would not experience emotion at all if it weren't for smell.

Trygg Engen explained in his
Odor Sensation and Memory
that smell has no identifiable attributes of its own but exists as an inherent part of what he calls "a unitary, holistic perceptual event. It is as if the memory of an odor is protected somehow, so that other experiences don't interfere with the memory of it, whereas pictures and sounds don't have that same protective effect." The feelings an odor triggers can change, however. For months after a house fire you might experience intense fear and anguish when exposed to the smell of smoke. As time goes on, the smell will revert to its default position—the pleasure of those long-ago evenings at summer camp when you roasted marshmallows around an open fire. The nose never forgets anything.

Researchers at the State University of New York have shown in animal studies that the memory center in the brain is like a reusable storage disk, thanks to an enzyme called protein kinase M zeta, which preserves long-term memories through persistent strengthening of synaptic connections between neurons. By manipulating kinase M zeta, the researchers believe they can effectively wipe out negative memories in human subjects without putting other data or the storage device itself (the hippocampus) at risk. Bad memories encompass a broad landscape, from the terrifying images (smells and sounds as well as sights) that haunt people with posttraumatic stress disorder to phantom sensations. Alzheimer's patients may also benefit from the discovery of the enzyme, which is bound up in the tangles that destroy existing memory and block memory storage.

I fantasized about teaching myself a whole new way to call up my stored memory of plants through using touch. Plants have exquisite textures. Some are like velvet and others prickly; some feel almost liquid to the touch and some are as smooth as glass. Leaves can be as soft as a baby's cheek, furry, or bristly. There are even plants that feel like sandpaper. Ruminating on the mysteries of smell science, I pondered fresh quandaries, such as why touch sensations, so like smells in that they run the gamut from pleasant to painful, lack the emotional component that makes smelling a rose so romantic and smelling a dead animal so rank. Why did evolution decide not to route touch through the limbic system? Touch lacks smell's influence over whom a person falls in love with and what risky situations to avoid. What determined that the nose should be given power and influence that even the eyes and ears do not possess?

We'll probably never know. Whether olfaction's special ability—the power to heal its own neurons (called neurogenesis)—might exist in the rest of the brain remains unclear. But we do know that the brain is plastic and rewires itself in response to the demands put on it. People who are blind develop a more discerning auditory system. Pianists train their fingers to perform feats of physical coordination that far exceed the innate potential of even an Oscar Peterson. I decided that I would retrain my insensitive, clueless, brain-dead fingers. I would teach them to smell.

That night in my attic office, holding that thought, I turned off the computer and entered the still, dark hallway. I didn't have my nose to guide me as it used to when I stayed up late working, making the darkness familiar—my smelly old house. Now I consciously ran my open palm along the rough plaster walls, over the cool, smooth banisters. So familiar and so novel at the same time. Before brushing my teeth I let the tap water caress my wrists and tried to deconstruct
wet
as if it were ... what? I was reminded once again that there are no words that specifically describe odors, only allusions to other things. A rotten-egg smell. The smell of sour lemons. Whereas objects painful to the touch are described as
scalding, sharp, jagged.

The next morning I tried to explain to Cam this new project I'd come up with, but, like so many predawn epiphanies, it dissolved the instant I put words to it. My smell-touch idea couldn't stand the light of day, that much was clear. Touch is not smell. It cannot be rewired to become smell. Touch is touch. I went to the refrigerator to get out the coffee beans and then noticed that apparently the dregs of yesterday's coffee were still in the pot. I mumbled an apology. Cam pulled a mug out of a cupboard and emptied the contents of the coffeepot into it.

"I made it twenty minutes ago," he said, smiling. "Guess you can't smell it."

He
was making progress, anyway. He would be over this in no time. He'd accept anosmia for what it was, stop fighting the diagnosis, and move on. Easy for him. For me the casualty numbers kept climbing. Over tasteless coffee and slimy cereal I told Cam that I couldn't seem to write. Gardening was an impossible topic. Reading didn't take me out of myself, not really, unless I was reading a printout of an article that had appeared in
Cell, Science, Nature Neuroscience, Neuron, Chemical Senses,
or some other science journal. Or an e-mail from someone whose name was attached to one of those articles and who had been kind enough to answer a question from a nonscientist.

As the weeks and months went by and my nose did not improve, I began to count my blessings. For real. Dr. Cushing had been correct when he told me that being a writer without smell was better by far than being a chef without it. I was finding that I could forget all about my nose for minutes, hours, even days by immersing myself in smell science.

But I was not my old self. I'd lost my memory not of how the past looked, which is mutable and untrustworthy, but of how it smelled, which is inviolate.

I still wanted to believe that a clinical approach to understanding olfaction would help me stop obsessing on catastrophic (outlandish) consequences—such as this new one I was chewing on:
You have only so much time to gather up all your memories and write them down, capture them somewhere (in the computer?) before your brain presses the Delete key.
If you think that's crazy, I said to my husband, how do you account for Proust? How did his brain suddenly give him back his lost childhood after he tasted a madeleine soaked in tea? Why couldn't that happen in reverse? I was worried I'd forget what people, places, and things looked (and sounded and felt) like if I didn't have smell to pack things together for storage in the hippocampus. Surely they'd become disconnected, scattered, and inscrutable.

Northwestern University neuroscientist and smell researcher Jay Gottfried described smell as a paradox in that it's both speedy and sluggish. Vision is speedy; a person can recognize a face in one-tenth of a second because the information from sight goes straight to the thalamus and high brain. Smells end up in the orbitofrontal cortex, the same place in the high brain that allows humans to recognize faces; it just takes an odor longer to get there. When this region is damaged, both face and odor recognition are lost. Professional wine tasters in France demonstrated the lag time between sight and smell when they were fooled into mistaking dyed-red white wines for red burgundies. Imagine their embarrassment when told
mais non!
They'd been tricked by a timing issue. The visual was signaling
red
in the thinking brain while the white-wine smells (lemon, straw, melon, toast, and grass) were still hung up in the limbic system.

Smells may be slow to register cognitively, but they operate with superb efficiency subliminally. Ever notice how swiftly your dog makes the dash to the door when he sniffs an unfamiliar dog outside? Compare that to his response to a passing car. He'll go to the window, but with nowhere near the same vase-toppling intensity. In humans too, smells carry potent emotional messages. This is partly why elderly people with dementia can still summon old memories with remarkable clarity even though more recent ones won't stick. An emotion-laden, long-ago fragrance can put an old man right back in the grove of cedars where he built forts as a kid; it can put an old woman into the '56 Chevy where she kissed a boy for the first time (his Old Spice and tobacco breath may be all that's left of him).

Then, too, smell-induced memory triggers weaken not with time but with overuse. The brain becomes desensitized by repetition. That's why sitting down to the fabulous pasta you learned to make on a recent trip to Italy doesn't have the emotional impact of pulling up a chair in front of a bowl of Chef Boyardee. It's been decades since you last smelled that inimitable blend of plasticky sweet ketchup and oversalted meat. A whiff of Bolognese sauce may take you into orbit, but it won't take you back in time.

Don't imagine that those old memories are authentic, though. The brain does not photocopy the past. Memories are remade with each act of remembrance. So while the same smell triggers the memory, the remembered events of the past are revised. They are reinterpreted, if you will, by subsequent incidents and emotional responses. Why? Memory's evolutionary purpose was to enable learning; thus, it
must
be highly flexible and subjective.

Richard Axel concluded his speech to the Nobel committee with a nod to Proust's remarkable insight that only smell can make the past present. Scientists and literature scholars alike have been pondering "the Proust phenomenon" ever since
In Search of Lost Time
was published in 1928. Proust knew intuitively that "olfactory sensory maps must be plastic," Axel said, "with our genes creating only a substrate upon which experience can shape how we perceive the external world." The great French novelist wouldn't have chosen quite those words, but
In Search of Lost Time
makes the point again and again.

The phenomenon is more complex than it seems. Researchers who assumed they could resurrect old memories in subjects by exposing them to fifteen familiar smells were disappointed. An odor has to be intricately detailed and nearly one-of-a-kind to unlock a memory. Proust's happy childhood memories came on a whiff of a tea-soaked cookie. This wasn't just any cookie but a madeleine whose buttery-sweet fragrance had been re-leased through chewing and swept up through the retronasal passage. There it was joined by the aroma of, again, not just any tea but the one already present (having infused the cookie's taste), now rushing its smell of lime-scented linden flowers to the brain by way of the nose.