 n
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.
"Results
from fMRI continue to tickle the imagination of researchers and the population
at large."
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: surgery 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. Basically, it does
not make sense at all.
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 electroencephalography and magnetoencephalography,
it does not provide a direct measure of neural or synaptic activity.
"The
higher the color signal on the fMRI image, the better the product must be."
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. | 
August 2005
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Reference: Rinck PA: Rinckside - Functional imaging
leads hunt for 'buy' trigger. Diagnostic Imaging Europe. 2005; 21,8: 25-27.
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