How tastes turn into feelings

Don Katz, in front of a picture of a cerebellum, believes that taste aversions are emotional, even social. (Dominic Chavez/Globe Staff)

In a lab at Brandeis University, Don Katz is trying to recreate spring break in rats. Or at least a particular spring break experience that, being March and all, is playing out at this very moment: college kid goes to warmer climate and drinks too much tequila; college kid gets very sick; when college kid tries to drink tequila again, his or her brain triggers a bad emotional response. This stuff, the brain says, tastes awful.

Katz, an assistant professor who studies the neurobiology of taste, thinks his rats may be a little better at listening to their brain than some college kids. He'll let the rats gorge on all the sugar water they can drink, then make them feel sick to their stomach by spinning them on a turntable. When presented with sugar water again, the rats pass because they associate the taste with a bad emotion. College kids - well, they're college kids.

Katz arrived in the relatively new field of taste research because he believes the way most neuroscientists study the brain is flawed. He thinks focusing on a particular part of the brain and ascribing some role to it - such as disgust - is wrong because it ignores the input of other regions of the brain.

"The whole purpose of the sensory system is to interact with its environment," he said, which is why, unlike most of his peers, he chooses to study animals while they are awake and alert. "Taste is incredible in that regard. Even the simplest taste means something. It forces a reaction. You can't put something in your mouth without having an emotional response."

By placing electrodes on different parts of the brain, Katz studies how the animals respond neurologically to a particular taste, what fires and what doesn't when they don't like something (yes, even rats do that thing where they stick their tongues out). And by looking at the brain's response over time - from when it recognizes there is something on the tongue, identifies it, and then decides whether it likes it or not - he is hoping to get some clues about how the verdict on good or yucky can change (see: tequila, the morning after).

The ability of the brain to trigger warnings about bad foods is "how we were able to eat and survive before the grocery store," Katz said. Once the brain has determined that a particular taste brings bad results, Katz has found that the emotional center will take control over the cortex and make the decision. This reaction is called a taste aversion, and Katz said most people have one, even to foods that aren't harmful to them (His is coconut).

He believes these taste aversions are emotional, and even social, and that's what he's currently studying in his lab. The rats didn't get sick from the sugar water; they felt sick because Katz made them feel sick, and the rats' brain made an emotional connection. He thinks a similar thing happens with chemotherapy patients - particularly children - who find their taste sensation has flipped on a food they once liked. The parents take the kid for a favorite meal before chemo, and then the child's brain forms a negative emotional connection between the two.

"If we can understand how this works, and understand how to set up the child's environment to make a clear distinction between the chemo and the food," he said, "then we can help the child keep them apart."

Diego Restrepo, the director of the neuroscience program at the University of Colorado-Denver School of Medicine, said that what distinguishes Katz is his willingness to step out of conventional thinking. "The idea of studying temporal sequences is new in taste," Restrepo said. "And that's what I like about him . . . He doesn't make assumptions; he brings new ideas to bear on a problem."

Katz, who looks younger than his 40 years and can get hopped up like a rat on sugar water when talking about his work, said that his taste research has drawn him to a larger conclusion about the neuroscience field.

"There's a big problem," he said. "We're studying sensation and emotion separate from each other. It just doesn't make sense.

"Neuroscience is afraid of consciousness, so we study the brain like it's a computer. But there's no computer like this," he said as he pointed to his own brain. "Everything is emotional."

Hometown: Canton, N.Y.; lives in Somerville

Education: Got a bachelor's degree in cognitive science from Brown University in 1989; earned a PhD in clinical psychology and neuroscience from the University of Indiana-Bloomington in 1997.

Family: Wife, Teresa, is a developmental psychologist at UMass Medical School. The couple is currently trying to adopt.

Hobbies: "I play saxophone in a bad band," he said. He and his wife also like to scuba dive.