Since ancient times, people have yearned to attribute human behaviors to a physical source within the head. Recently, neuroimaging technologies have given us the technical ability to look at the living brain, its structures, and some of its functions without the need for invasive procedures. However, the . science has a long way to go before these technologies can allow us fully to appreciate the anatomical and physiologic underpinnings of human thoughts, states of mind, motives, will, or behaviors.
In this Article, we use an historical overview to introduce the various new technologies for imaging the brain. Today, the goal of medical science is the same as it has always been: to make medical technologies valid, useful, effective, and safe; and to guide appropriate uses while protecting the public from the misuse of them. Brain images are particularly vulnerable to misuse because they are so visually attractive. This visual power can easily result in misunderstanding about what the images show and what they mean. History shows, however, that legitimate science and unfettered showmanship have always proceeded on parallel tracks. Currently, there is great need for guidance on the appropriate uses of brain imaging within medicine, but also in fields outside of medicine, and particularly in the courtroom in aid of judges who must determine whether the images, and expert testimony about them, can be admitted into evidence. In Part II of this Article, we discuss the discovery and growth of these technologies. In Part III, we discuss some of the dilemmas that have been raised by the use of brain imaging in the courtroom, highlighting criminal cases in which the outcome was strongly swayed by jurors who misinterpreted the meaning of the images. We argue that brain images be admitted into evidence only for the purpose of linking a structural abnormality to a specific deficit, and that functional brain images not be admitted for the purpose of establishing responsibility for, motivation for, or propensity to commit a particular behavior, or to show an inability to control a particular behavior. For example, the current use of fMRI findings to establish the cause of certain behaviors, or responsibility, motivation, or propensity for them, is premature and ignores the complexity of brain function. Indeed, given the current state of medical and scientific knowledge about the brain, once admitted as evidence, the courtroom is an inadequate forum for determining the "truth" of such evidence. The importance to judges of obtaining careful scientific guidance on these technologies cannot be understated, and we argue that professional medical societies could provide invaluable assistance by issuing guidance for judges faced with the task of evaluating the evidentiary value of brain images and the testimony of the expert witnesses who will interpret them. In Part IV, we conclude that a body such as the Institute of Medicine could serve the courts and the public by conducting periodic reviews of current brain imaging research, convening scholarly committees to consider various uses and needs for the technology both within medicine and in related fields. We further suggest that the President's Council on Bioethics continue to serve an educational role as a multidisciplinary advisory body on these issues, and as a forum and resource to the public on the ethical issues raised by the use of these technologies.
II. IMAGING THE MIND: A BRIEF HISTORY OF BRAIN IMAGING
What is Mind?
It does not Matter.
What is Matter?
Since antiquity, scientists have searched for the source of our reason, emotions, and behavior. Hippocrates, a trained Pythagorean, chose the head as the place where reasoning resides because it resembled a globe-the ideal geometric shape.1 Observing that patients with depressed skull fractures had convulsions, Hippocrates hypothesized that certain behavioral disorders were influenced from the head. …