Functional imaging leads hunt for 'buy' trigger

In 1990, Dr. Jack Belliveau and colleagues at Massachusetts General Hospital in Boston published the results of a successful experiment designed to observe and image stimulation of the human visual cortex on MRI.¹ Using the first-pass effect after bolus injection of a contrast agent, they demonstrated changes in cortical perfusion upon activation with a photic stimulus.

The use of bolus tracking to study changes in perfusion was an exact analog of previous experiments involving PET or SPECT to observe radioisotope tracers. Performing such a function-related experiment with MRI instead of nuclear medicine techniques offered vastly superior spatial and temporal resolution, without administering radioactive materials. The need for dual injection of contrast, however, posed a problem, especially for studies of brain activation in normal individuals.

This disadvantage was resolved by the BOLD-contrast mechanism, first described by Dr. Seiji Ogawa.² His elegant technique for demonstrating brain activation has led to a rapid proliferation of functional MRI over the past few years. BOLD-contrast relies on the fact that paramagnetic deoxyhemoglobin possesses a far stronger magnetic moment than diamagnetic oxyhemoglobin. Interaction of the bulk magnetization of deoxygenated blood with the external field sets up local field variations in and around blood vessels. These susceptibility effects can be measured using appropriate MRI sequences.

The only energy source in normal brain cells is the oxidation of glucose. Because the glucose storage capacity of brain cells is negligible, the brain depends heavily on a constant supply of glucose and oxygen via the capillaries. This increased demand leads to more blood flowing to the activated area. This, in turn, decreases the local susceptibility effect, which can be visualized with susceptibility-sensitive imaging techniques.

Both approaches try to determine how the brain reacts when certain stimuli reach its owner. Today an increasing number of institutions perform fMRI. Most of this work is done for research purposes, though routine applications are on their way.

fMRI has replaced MR spectroscopy as the favorite MR research modality. MRS fascinated researchers, but this early enthusiasm has faded. Results from fMRI, on the other hand, continue to tickle the imagination of researchers and the population at large because it shows the brain at work and reacting to the environment. MR imaging can detect changes in brain hemodynamics that correspond to mental operations.

fMRI has fascinated me from its very beginning. Suddenly, we had access to a noninvasive safe technique that could be repeated in the same person. One could see almost real-time cerebral responses to a range of activities, including viewing a picture (activation of the occipital lobe), listening to music (activation of the area around the Sylvian fissure in the temporal lobe), and physical interaction (activation mostly in the contralateral temporal lobe).

Today, fMRI maps that show brain regions responsible for speech help presurgical planning. They enable estimation of the risk of postoperative deficits and appropriate selection of treatment: sur-gery versus radiation or chemotherapy.

The technique may also play a role in the assessment of psychiatric disorders. Cognitive scientists are at the forefront of research applying fMRI to better understand brain function. One such study cast doubt on the belief that a group of severely brain-damaged people were unaware of their surroundings. The researchers discovered that these individuals could, in fact, register what was going on around them, but they could not respond.³ The technology could be a powerful tool to help doctors and family members determine whether a person has lost all awareness.

Consumer industries are also harnessing fMRI. Automobile manufacturer Daimler-Chrysler, in collaboration with the University Hospital in Ulm, Germany, discovered that male test subjects tend to use a different thought process than females when navigating a maze. Comparison of fMRI maps revealed that most men try to configure a map of the maze in their mind, while women are more likely to use landmarks for orientation.

Other studies of in vivo brain activity have looked at gamblers and the process of deciding between options. Researchers at Baylor College of Medicine in Houston, Texas, used fMRI to examine the mental activity of people drinking cola. Images indicated that Pepsi activated parts of the brain linked to pleasure, while Coca-Cola activated areas dealing with trust and memory.⁴ In another study, Daimler-Chrysler concluded that the reward centers in men's brains are activated when they look at racy sports cars.⁵

These and similar studies form part of neuroeconomics and neuromarketing, a fascinating offshoot of economic science. Neuroeconomics combines psychology, economics, and the medical neurosciences. James Montier has written an entertaining review of state-of-the-art neuroeconomics.⁶ I decided to read some of the original articles that Montier cited. The authors of one paper describe their results:

"This study examines the bold response one TR (1.5 s) before the results screen, because decision making for cooperation is likely to be salient at this TR independent of the subject's position in the game."⁷

This sentence does not actually describe the results of a study.

The combination of medical sciences (particularly imaging) and economics has created a hybrid discipline that lacks a solid scientific basis. Economic theories are based on observations, and, in this respect, they are close to history and philosophy. Economic science uses mathematics to create models of social processes or speculative predictions of the stock markets. Such models are prone to failure. If you take "scientifically created" pictures, however, people believe that the pictures show something relevant. The higher the color signal on the fMRI image, the better the product must be. Yet, unlike electroencephalog-raphy and magnetoencephalography, it does not provide a direct measure of neural or synaptic activity.

Good luck with this idea. Some people even believe that fMRI can be used to read thoughts, allowing market researchers to pry a little. Companies regard the chance to find out what their customers really think as a great opportunity. But fMRI does not show what people think. Most people do not remember which product or person is featured in a given commercial.

When confronted with a certain endeavor, I sometimes ask myself whether it is scientifically sound and whether I would invest my personal money in it. Neuroeconomics is not at all scientifically sound. The combination of a reasonably exact science with a "rubber" science will always produce nonscientific results. On the other hand, people will invest in it.

Nearly 50 years ago, Vance Packard wrote in his best-selling book The Hidden Persuaders:

"This book is about the large-scale efforts being made, often with impressive success, to channel our unthinking habits, our purchasing decisions, and our thought processes by the use of insights gleaned from psychiatry and the social sciences. Typically these efforts take place beneath our level of awareness; so that the appeals, which move us, are often, in a sense, 'hidden.' The result is that many of us are being influenced and manipulated, far more than we realize, in the patterns of our everyday lives.⁸

"We still have a strong defense against such persuaders: we can choose not to be persuaded. In virtually all situations we still have the choice, and we cannot be too seriously manipulated if we know what is going on. It is my hope that this book may contribute to the general awareness. As Clyde Miller pointed out in The Process of Persuasion, when we learn to recognize the devices of the persuaders, we build up a 'recognition reflex.' Such a recognition reflex, he said, 'can protect us against the petty trickery of small-time persuaders operating in the commonplace affairs of everyday life, but also against the mistaken or false persuasion of powerful leaders."

Packard knew nothing about "reading the brain" with fMRI. Yet he predicted that what you see in those images might not really reflect the "buy button." His book is still worth reading today. Only the scientific toys have changed. But even methods like fMRI and PET will not create a major step forward in understanding how the human brain deals with marketing.

PROF. DR. RINCK is a visiting professor at the University of Mons-Hainaut, Mons, Belgium. He can be reached at peter.rinck@umh.ac.be

References

1. Belliveau JW, Rosen BR, Kantor HL, et al. Functional cerebral imaging by susceptibility-contrast NMR. Magn Res Med 1990;14(3):538-546.

2. Ogawa S, Lee TM, Nayak AS, Glynn P. Oxygenation-sensitive contrast in magnetic resonance image of rodent brain at high magnetic fields. Magn Res Med 1990;14(1):68-78.

3. Schiff ND, Rodriguez-Moreno D, Kamal A, et al. fMRI reveals large-scale network activation in minimally conscious patients. Neurology 2005;64(3):514-523.

4. Jakobson L. Tech watch: mental marketing. Neuromarketers believe medical technology can help them understand what consumers really think about products. Incentive Magazine, Sept. 20, 2004 (http://www.incentivesatwork.com/incentive/search/article_display.jsp?vnu_content_id=1000629432).

5. Blakeslee S. If your brain has a 'buy button,' what pushes it? The New York Times, Oct. 19, 2004. (reprinted in international Herald Tribune, Oct. 21, 2004.)

6. Montier J. Emotion, neuroscience and investing: investors as dopamine addicts. Global Equity Strategy. Dresdner Kleinwort Wasserstein Securities, Jan. 20, 2005.

7. McCabe K, Houser D, Ryan L, et al. A functional imaging study of cooperation in two-person reciprocal exchange. PNAS 2001;98(20):11832-11835.

8. Packard V. The hidden persuaders: what makes us buy, believe and even vote the way we do? New York: D. Mackay & Co, 1957;7:295.