Healthy Manhattan: This Is Your Brain on Coke or Pepsi

Which do you like better, Coke or Pepsi? You may be surprised by the answer.

The Pepsi Challenge TV commercials from the ’70s and ’80s featured people blind-tasting Pepsi or Coke. Not surprisingly, people chose Pepsi. Yet Coke continued to outsell Pepsi.

In 2003, neuroscientist Read Montague decided to repeat the Pepsi Challenge with subjects lying in a functional magnetic resonance imaging (fMRI) machine, which tracks changes in blood flow related to neural activity in the brain.

Most subjects in Montague’s study chose the Pepsi sample as better tasting, and Pepsi tended to produce a stronger response in the brain’s ventral putamen, a region thought to process feelings of reward. But in a second test when subjects

were told which brand they were drinking, more said they preferred Coke.

Montague observed that their brain activity also changed. The knowledge that they were drinking Coke increased activity in the medial prefrontal cortex, an area of the brain associated with thinking and judging. This seemed to validate the claims of marketers that they can influence consumers’ decisions. Neuro-marketing was born.

Marketing is only one field in which neuro-imaging is applied. Studies done in labs across the world provide researchers with new insight into how our brains work. This knowledge could help in the treatment of diseases such as Alzheimer’s or Parkinson’s, say neuroscientists. It could also help in the treatment of mental illnesses, such as anxiety disorders and depression. Neuro-imaging reveals what parts of the brain are involved in some of the most fundamental human attributes, such as faith, hope, fear, grief and love. As scientists learn more about how humans make decisions, new interdisciplinary fields of study are emerging, like neuroethics, neuro-law and neuro-economics.

Since the early 1990s, fMRI has become the most widely used brain mapping tool. By the mid-’90s it had changed the way researchers “think about the mind-body interface,” according to Joy Hirsch, director of the Program for

Imaging and Cognitive Sciences at the Columbia University Medical Center.

“And so we really have in our hands about 15 years for this period of transformation, of understanding mind events in terms of the underlying working parts, that is, the underlying physiology of the brain,” Hirsch said.

When neural cells are active they consume more energy. More blood flows to regions of increased neural activity, and the fMRI machine measures the blood flow in the brain, providing researchers with information on brain activity.

Using fMRI, researchers can observe the brain while a subject performs an assigned task, seeing how the brain reacts to stimuli or works during mental processing. By learning about how people’s brains function, researchers can begin to understand decisions or emotions in more scientific ways.

“That’s what’s amazing here,” said Hirsch, “we objectify sciences that have been subjective in the past.”

Before fMRI, psychologists could ask patients questions and use their answers to assess their mental conditions. Researchers can now ask the same questions while observing the conscious and subconscious neural processes in the brain that mediate emotion and cognition.

Scott Huettel, the director of the Center for Neuroeconomic Studies at Duke University, conducts studies in his lab to better understand the basic mechanisms that underlie decisionmaking, and how those mechanisms may differ from person to person.

“So the working hypothesis is that the decisions reflect the interactions of a range of different brain systems; that an understanding of brain function will also predict which a monthly advertising supplement individuals make what sort of decisions,” Huettel said in a telephone interview.

Individuals make different decisions and will adopt different strategies to cope with various situations. Huettel believes that those differences represent differences in the brain. By understanding those differences, scientists could then predict how people will behave under specific circumstances.

Recently, I took part in a study at the Columbia Program for Imaging and Cognitive Science at the Columbia University Medical Center. I was asked to perform a task inside the fMRI machine, which costs between $3 million and $4 million and looks like a regular MRI machine. Lying on my back in the tunnellike center of the device, I could see a screen through goggles I adjusted over my eyes by turning various knobs.

I was asked to perform visual tasks by closely observing images flashing on the screen. For one of the tests, I had to look for a ball with lines angled to the right or left, and to indicate what I thought I saw by pressing buttons on a pad placed under my hand.

In the next room, Michelle Umali, a Ph.D. candidate conducting the study, could see my brain activity on a screen. She wanted to know if certain images influenced my performance at the tasks.

After an hour in the fMRI machine, I was anxious for the study to end. The inside of the machine feels like being stuck in a narrow tunnel, so some people get claustrophobic. Most fMRI experiments last between 15 minutes and an hour.

At the end of the study, I viewed images showing activity in various regions of my brain. The colors on the images meant little to me, but I was glad to hear that everything seemed to be in working order.