Taste: Surprising Stories and Science About Why Food Tastes Good (50 page)

Roger and I visited PhD Joy Hirsch at the fMRI center at Columbia University, where she is a professor and director of the Program for Imaging and Cognitive Sciences. I wanted to understand the science behind how fMRIs worked and, while there, have our brains scanned while we experienced food. She agreed to do scans of us looking at pictures of food. This would be interesting. Roger and I make such different choices when it comes to eating that I thought there would surely be a neurological explanation.

We each chose photographs of food that we loved as well as those we hated. My loves: tomatoes, crusty bread (I knew an image of Tartine Bakery’s sourdough would light me up like a Christmas tree), Maryland steamed crabs, sweet potato fries, and Champagne. Roger’s were steak, steak, and steak, as well as baby back ribs, ice cream, deviled eggs, burgers, mashed potatoes, and strawberries.

Roger went first, and then it was my turn. I was instructed to lie flat on a platform while the technicians positioned my head in place so they could get a
good image. Then someone hit a button and I was conveyed into the fuselage like a duffel bag on a belt.

Meanwhile, Roger sat inside a glass-walled booth talking to the technician who operated the fMRI machine.

“What are you doing?” he asked as the man adjusted some settings on his computer screen.

“Resizing the image field to fit her brain,” he said to Roger. I imagine Roger’s eyes widening at this.

“Really?” he said, “Whose brain is bigger?”

“Hers.”

Roger later told me that my brain was bigger, also having to confess that, yes, he’d asked. Bless his heart.

Of course there is no correlation between human brain size and intellect, I graciously reminded him.

Above me inside the fMRI was a mirror cleverly positioned so that I could see a computer screen while on my back. A technician told me to focus on the screen, and then a slide show of my favorite foods flashed before my eyes, one at a time, slowly enough that they would register in my brain. Then we stopped, the technicians changed the slide show, and I saw my most-hated foods (eggs, pine nuts, liver, and so on).

According to Hirsch, we both showed robust activity in the fusiform gyrus, an area that is activated when bird-watchers look at birds, or car lovers look at cars. She told us that the data indicated we both had a strong interest, and perhaps even an expertise, in food. The rest of the slides showed one huge difference between the two of us. Roger showed much more robust activation when looking at pictures of his favorite foods.

“He’s got an emotional attachment to these foods that he likes,” said Hirsch. “This suggests to me that what drives his love of food is really a
love
of food. He’s driven by his likes, not his dislikes.”

I, on the other hand, showed the brain of a restrained eater. I eat what I like and allow myself an occasional indulgence, but I definitely watch how much and what I eat. I restrain my diet. My brain, compared with Roger’s, showed much less activity when I looked at the food I loved, and more activity when I looked at the food I dislike (versus his brain when he looked at food he dislikes).

“You seem to be more controlled, more emotionally involved with foods you
don’t
like,” Hirsch said.

This crushed me. Does Roger live in a happier world than I do simply by
not putting any restraints on his diet? Does having a guilt-ridden psyche rob me of some of the joy that Roger experiences daily? And then I wonder whether his HyperTaster tongue has anything to do with this. How much more sensory input does he get than me and, more important, does this translate into more pleasure? Does he get more out of the food he loves than I do?

Hirsch was careful not to read too much into the data.

“It suggests that the individual differences in our brain responses are key to our individual personality differences. It fascinates me that one can look at brain patterns and make inferences in behavioral patterns,” she told me before revealing one last truth. “Your brain’s a little smaller than Roger’s,” she said.

“Really?” I asked.

“Female brains usually are smaller than male brains. It’s quite proportional to body size,” she said.

I should have slipped that fMRI technician a twenty for lying so convincingly to Roger.

Think about the most rewarding food you could eat. For many, this would be chocolate. Chocolate lights up the same part of the brain—the reward center—that is activated by gambling and cocaine. Dr. Hans Breiter of Massachusetts General Hospital writes, “The same neural circuitry is involved in the highs and lows of winning money, abusing drugs, or anticipating a gastronomical treat.”

This is all due to dopamine. When you eat chocolate—or throw dice at a craps table or use drugs—dopamine floods your brain. It’s what makes you respond the way you do to pleasurable activities like eating. Recent research on the brain’s reaction to food has lead to a number of theories about why some people overeat and others don’t.

One theory says that when the dopamine system works, the result is a very simple cause and effect. Treat: reward. Treat: reward. If you are lean, it’s likely that this system is functioning properly. But someone deficient in dopamine receptors may not get a proper reward signal from eating chocolate. It might go something like this—Treat: almost-reward. Treat: almost-reward. When the reward doesn’t feel complete, this person may keep going back for more of the chocolate, trying desperately to get a full-fledged reward.
Some obese people lack dopamine receptors, so this is one theory explaining why they overeat.

Another theory says that obese people get
more
pleasure from eating than lean people do. In this model, their system rewards them handsomely for delivering a treat, so that they are more motivated to eat the chocolate (or any food) again and again. A third theory says that obese people may
expect
a greater reward, and this expectation keeps them eating long after they are full.

This learning just barely scratches the surface of the brain’s role in why some people tend to gain weight and others do not. It’s a burgeoning area of science, given the enormous societal costs of obesity and overweight. But it’s just now coming together with research on the chemical senses. Our brain is so damn smart, so damn complicated, and so damn inscrutable that we know very little about how it processes most eating.

We know that the Basic Taste sweet shows more action in the brain than the other Basic Tastes, perhaps because it’s so important for us to ingest calories. We know that smell lights up more widely dispersed areas of the brain than taste. This makes logical sense since there are an almost unlimited number of smells and only five Basic Tastes.

We know that the sense of taste is more entwined with the sensation of being full and with eating disorders than smell is. Monell’s Johan Lundström writes, “The sense of taste might be a good stepping stone, by itself or in conjunction with other senses, in our struggle to understand the explosion in obesity rates and eating disorders.”

If we know little about the senses of taste and smell, we know even less about how the sense of touch works in our brain. These days, scientists are most intrigued by the integration of the three senses that combine to form flavor. When we put a barbecued rib in our mouth, we don’t experience it separately as the taste, the smell, and the texture. Instead we integrate the information into one perception: the flavor of the rib. What that flavor looks like and where it happens in the brain are still a bit of a mystery. Add vision and hearing to the equation and you’re really pushing the boundaries of current scientific knowledge. Lundström is working on a study that will use the fMRI technique to map the brain while a subject is simultaneously tasting, smelling, feeling, hearing, and watching a stimulus food. Of course it won’t be exactly the same as eating the food normally, since the subject will be lying in a tomb-like tunnel, with an olfactometer up his nose and a taste tube in his mouth, but it will be as close as we can get within the limits of today’s neurogastronomy.

One study mapped the brains of expert wine tasters. It showed that the way their brains responded to wine was tremendously different from the brains of novices. There was “higher cognitive processing” of the wine while it was in the mouths of the experts, as well as after they swallowed and experienced mouth-smelling. Experts’ practice in the course of their professional wine careers (and ostensibly at the dinner table and elsewhere) made more areas in their brain light up, specifically those in the neocortex.

Not only do tasting experts use more areas of the brain, they can enjoy the processing better than novices. Says Baba Shiv, professor of marketing at Stanford University, “An expert is a person who knows how to derive maximum pleasure from the consumption experience.”

Humans are drawn to the odd, the unique, the unusual. When it comes to taste, there are a few foods that fit this bill, namely the artichoke, the miracle berry, and the Szechuan button.

The artichoke I highly recommend. When artichokes are fresh, there’s nothing like them in the world. They have a subtle flavor that’s very mildly sweet and slightly vegetal. The flesh of the defended heart pulls apart with the delicacy of a scallop. The outer leaves are not entirely edible, but the fleshy ends are fun to eat as a sauce, butter, or mayonnaise delivery vehicle. Dip first. Then scrape off with your teeth what little flesh you can get.

Just like every other aspect of our experience with food, an individual’s experience with artichokes varies greatly depending on anatomy and genetics. For some people, immediately after eating a fresh artichoke, everything that follows it tastes sweet. This can be fun if all you’re drinking is water, but it’s less so when you’ve spent good money on a bottle of wine that now tastes wrong. And if you grab your glass of water to cleanse your palate after the too-sweet wine, that could taste wrong, too. This taste magic is due to the cynarin in the artichoke.

Other people find that artichokes make their wine and water taste bitter or metallic. To fix any of the effects of eating artichokes together with wine, Tim Hanni, Master of Wine, suggests “a judicious addition of salt and acidity.” Others
say it’s best not to pair wine with artichokes at all. Douglas Keane of Cyrus restaurant pairs the artichokes on his menu with dry sake.

If you’re not drinking wine with your artichoke, enjoy its lovely flavor and the extra bit of sweetness you get from whatever follows. The good news is that the change in taste perception is short-lived. A palate-cleansing bite of bread is supposed to do the trick. I couldn’t tell you, though, because I don’t experience any magical effects from eating artichokes with wine.

If you eat another taste-tricking fruit, the miracle berry, its magic will last much longer. I cannot recommend this, to be honest. My experience with the wonderful, magical, miracle berry was . . . not so much. The miraculin in the berry is purported to make everything you taste after it sweet. This isn’t entirely true. It makes sour (and some bitter) tastes sweet. You can eat lemons like candy. Tabasco hot sauce tastes like Spicy V8 juice. I found that the sweetness profile tastes more like that of an artificial sweetener such as stevia or sucralose than sugar, with a bitter and artificial lingering taste in the finish. It was cool, but I certainly wouldn’t call it delicious.

I viewed miracle berries as no more than a novelty until I heard that someone tried to commercialize miraculin, the magical compound in the fruit, in the 1970s so it could be used as a sweetener. The company that developed the sweetener applied to the U.S. Food and Drug Administration (FDA) for approval to use it in food. The FDA denied their application, which meant they’d have to do a lot more testing, which would cost a lot more money. At this point, the company simply gave up. A few people in the industry whisper that the “Big Sugar” lobby was behind this, but I couldn’t get anyone to say it on the record.

Szechuan buttons look demure enough: tiny yellow flowers with a bright green stem. You might expect them to taste like kiwi or even the edible flowers, nasturtiums, they’re so darn pretty. But when you chew through the flowery pistils of the Szechuan button, you will first notice that it is irritating. Then you will feel it start to numb your tongue and cheeks. And finally, when it’s in full bloom in your mouth, you will think you can fly to the moon. Well, maybe not that far, but the button certainly is energizing, like touching your tongue to a battery.

The spilanthol in the button is what makes it tingly or numbing, as different people describe it. The effect is similar to eating Szechuan peppercorns but much more pronounced. Michael Nestrud, formerly of the Cornell University Food Science department, notes that the structure of the spilanthol molecule looks suspiciously like that of capsaicin, the active compound in chile peppers. They
both have numbing effects, although the button’s effect comes on much faster and hangs on much longer than that of capsaicin. In some parts of the world, instead of the Szechuan button, it’s known as the toothache plant because of its anesthetic quality.

When I tried Szechuan buttons I most certainly, definitely, positively felt the sensation, which was like nothing I’d experienced before. After the tingle turned into a buzzing numbness, I reached for a glass of water to cleanse my palate. The water spontaneously combusted in my mouth—a sensation so strong it scared me for half a second. Szechuan buttons are an unbelievable sensory experience, but it’s not one I want to experience again. I prefer my food a little less magical.