An Evening at the Rubin Museum: Attached to Touch

When I think of grated mountain yam (also known as “tororo”), my mind goes back eight years to when I first tried it in Japan. My great-aunt sent a large cardboard box from the countryside filled with potatoes, carrots, beans, a sack of rice wrapped in cloth, and mountain yams—all harvested that morning. My grandmother grated the tororo over a bowl until it was filled with the slimy, white paste, which we ate over rice. It was refreshing and bizarre—and so delicious that I became obsessed.

If you were to ask Tom Colicchio (renowned chef and celebrated judge on Bravo TV’s Top Chef) what he thinks of grated mountain yam, he would picture the same bowl of slimy paste and cringe with disgust. In fact, that’s exactly what he did on Wednesday evening when Dr. David J. Linden asked if there was a specific texture in food that he couldn’t stand. Unfortunately, Colicchio did not elaborate on his memory of mountain yam; though it must have been pretty bad judging by the way he shuddered. We make associations with certain smells, textures, and tastes the first time we experience them, and these associations greatly affect the way we respond when we encounter them again, Dr. Linden said.

As the first event of the Rubin Museum’s eighth annual Brainwave series, the Top Chef and Johns Hopkins University neuroscientist paired up to discuss the importance of the basic five senses –including hearing, seeing, smelling, touching, tasting—in the kitchen. They also discussed how genetics play a major role in the foods we favor or disdain, and why human evolution has changed the way our bodies react to certain flavors.

Tom Colicchio (left) speaking with David J. Linden (right). Photo courtesy of the Rubin Museum of Art.

Tom Colicchio (left) speaking with David J. Linden (right). Photo courtesy of the Rubin Museum of Art.

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Acquiring Taste and Smell

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From left, panelists Kathryn Morgan, Gary Beauchamp, and Joan Marrinan listen to Susan Watterson describe getting a sense of the flavors of foods as she’s cooking.

Last night’s Neuroscience and Society series event was a feast for the senses and the mind, from hearing stories of training noses and palates to trying to train or at least understand our own.

The session, “How Your Brain Distinguishes Tastes and Aromas,” started with a quick science primer by Gary Beauchamp, director and president of Monell Chemical Senses Center. In broad strokes, our conscious taste perception involves the tongue, palate, and part of the throat, while odor perception has two paths: sniffing (orthonasal) or swallowing food, which drives the smell upward to olfactory sensors in the nasal cavity (retronasal).

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Primer on the Senses

We
traditionally refer to five senses: sight, hearing, taste, smell, and touch.
But it’s not that simple. Our new primer, on the senses, delves into the complex systems
that enable us to connect to the world.

It’s a dynamic process. The brain is not
simply a receiving station for sensory signals, and what we see, hear, and feel
are constantly shaped by emotions, memories, moods, and beliefs. Our sense of
the world is a creation of the brain, and the same physical sensation may be
experienced quite differently at different times of life, and even from day to
day.

Read Part I of the primer now; Part II will post on the Dana
Foundation homepage
 on Monday,
August 26.

–Ann L.
Whitman

Scentsing Reality

I had my first colorblindness test in seventh grade. Well, it wasn’t really a formal colorblindness test so much as a side effect of a science class in which we were discussing vision.

“Look at the picture in your textbook,” the teacher requested. “What number do you see?”

“17,” we answered in near-unison.

“No…” started one boy hesitantly. “It’s a two.”

You can imagine what happened next. As middle schoolers are all too wont to do, we each turned simultaneously to stare at him, our mouths agape. After further clarification that he really did see a 2 despite trying his hardest to see the 17, our teacher confirmed what we already suspected.

“Erik, I think you’re colorblind.”

He looked as if he were about to cry, and I can imagine why. He had just discovered (in front of all his peers, no less) that he was markedly different—that there was something wrong. Something wrong with him. But in reality, nothing was wrong with him, per se. Most likely, a gene on the X chromosome of his ancestral line had mutated decades ago and had been passed down through generations until it manifested itself in him as anomalous trichromacy, a mild color-blindness disorder that primarily affects males. But despite the innocuous nature of color blindness, it has serious implications for his perception of reality. After all, he saw an image that nobody else in that room could perceive. And what is reality, really, if not our perception of sensory information?

On Wednesday night, Dr. Richard Axel of Columbia University began a talk, part of a lecture series presented by the Columbia University Mind Brain Behavior Initiative and sponsored by the Dana Foundation, by arguing just that. He opened with an idea that is, at first, a hard pill to swallow. “Your reality does not exist outside of your brain.” It may seem simple on the surface, but thinking deeply about this question makes me very uncomfortable. How is my world different from everyone else’s? What am I incapable of perceiving? What am I perceiving incorrectly? Am I living a lie?! (OK, perhaps a bit dramatic.)

Axel explained that information from our environment enters our brain through our five senses. Our brain synthesizes this information to create a reflection of the outside world—this synthesis is our reality. And if our brain is constructed based on instructions issued by our genes, then it follows that we are trapped in terms of the type of reality we can perceive. We don’t choose our genes, and because of genetics, Erik could perceive something I could not and vice-versa. Pythons, Axel pointed out, have an extra sensory system—infrared—that allows them to perceive things in the environment that we cannot.

Axel studies one particular sense, olfaction, to attempt to address the question of how the brain uses sensory information to form our subjective realities. Humans sense odors through olfactory receptors located in our noses, just below the spot where a pair of sunglasses would sit. We have approximately 400 functional genes that encode around 1,000 different types of olfactory receptors (note that 1,000 represents the number of variations of receptors; we have approximately five million receptors in total). And here’s the thing: Those 1,000 types of receptors are identical from person to person. We all have the same receptors that are stimulated by the same odors with the same molecular structures. Furthermore, those odors activate certain parts of the brain in exactly the same way from person to person.

So why can one person hate one smell while another loves it? Take, for example, vanillin. Vanillin is a phenolic aldehyde that is composed of eight carbon atoms, eight hydrogen atoms, and three oxygen atoms, but it is more commonly recognized as a smell of scented candles or the flavor of vanilla ice cream. Its structure is easily recognized and therefore easily quantifiable. When I smell vanillin, it activates my olfactory system in precisely the same way that it activates yours. I love the smell, but I know people who can’t stand it.

Axel said he will spend the rest of his life trying to find out how the brain blurs and distorts objective sensory input (like the shape of an odor molecule) into a subjective sensory experience (“Whoa, that smells terrible.”). Unfortunately he had no answers for us at last night’s lecture, but some interesting questions lingered. While loving one smell and hating another might seem bland, there are other aspects of our environment to consider—what sensory abilities do we lack? Why can animals sense an oncoming natural catastrophe? What is there that we can’t see? How different is my reality from yours?

On the other hand, you can simply ignore these questions and continue living comfortably. After all, it’s your world—I just live in it.

–Caitlin Schneider

Blindness and Sensory Perception

Ever since studying Oedipus Rex and The Odyssey in tenth-grade English class, I’ve been exposed to the idea of the blind seer. From at least the heyday of ancient Greece, people have thought that with loss of sight comes a heightening of other senses (which, in literature, means extraordinary perception and foresight, usually resulting in tragedy. Oedipus, do you really want Tiresias to tell you who killed your father?).

Recent research has found that many blind people do, in fact, experience a heightened sense of touch. But this may not occur merely due to blindness, but from increased use.  

Scientists at McMaster University tested 28 profoundly blind people and compared them to 55 seeing adults. When asked to identify the textured patterns pushed against their fingertips, blind participants performed better than sighted participants. Braille readers performed better still, especially when researchers tested their reading finger.

But when the textured patterns were pushed against the participants lower lips, there was no difference in the performance of participants. Therefore, concludes the study authors, use improves skill.

How can blindness impact the other senses?

Let’s look at smell: A study from researchers at the University of Copenhagen compared the olfactory responses of normally sighted study subjects to those blind from birth. Functional magnetic resonance imaging revealed more blood flow to primary and secondary olfactory areas in the congenitally blind subjects. A study from the University of Montreal—comparing odor detection abilities of 11 congenitally blind and 14 normally sighted study subjects—concluded that the blind participants had better senses of smell only in areas relating to environmental assessment.

Compensatory sensory perception appears to result from use, which can lead the brain’s connections to change and reorganize. A “third eye” of the blind may therefore exist in some neuroplastic fashion—but not in the way presented by Sophocles and Homer.

–Johanna Goldberg

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