Picturing Personhood

Brain Scans and Biomedical Identity

Joseph Dumit

• Publisher: Princeton University Press
• Year: 2021
• ISBN:
  9780691236629
• Topic: Medicina
• Subtopic: Diagnostica per immagini

By showing us the human brain at work, PET (positron emission tomography) scans are subtly--and sometimes not so subtly--transforming how we think about our minds. Picturing Personhood follows this remarkable and expensive technology from the laboratory into the world and back. It examines how PET scans are created and how they are being called on to answer myriad questions with far-reaching implications: Is depression an observable brain disease? Are criminals insane? Do men and women think differently? Is rationality a function of the brain?
Based on interviews, media analysis, and participant observation at research labs and conferences, Joseph Dumit analyzes how assumptions designed into and read out of the experimental process reinforce specific notions about human nature. Such assumptions can enter the process at any turn, from selecting subjects and mathematical models to deciding which images to publish and how to color them. Once they leave the laboratory, PET scans shape social debates, influence courtroom outcomes, and have positive and negative consequences for people suffering mental illness. Dumit follows this complex story, demonstrating how brain scans, as scientific objects, contribute to our increasing social dependence on scientific authority.
The first book to examine the cultural ramifications of brain-imaging technology, Picturing Personhood is an unprecedented study that will influence both cultural studies and the growing field of science and technology studies.

Chapter 1

Introduction

Probably one of the most important initiatives we have ever undertaken is our support for positron emission tomography (PET), an intriguing new research technique. . . . With PET we will be able to examine what happens functionally, in the living human brain, when a person speaks, hears, sees, thinks. The potential payoffs from this technique are enormous.

—Dr. Donald B. Tower, Director of the National Institute for Neurological and Communicative Disorders (from the NIH Record, 1980)

In science, just as in art and in life, only that which is true to culture is true to nature.

—Ludwig Fleck

Sitting in a paneled conference room at the University of California, Los Angeles, with framed brain images on the wall, I am talking with Dr. Michael Phelps, one of the fathers of positron emission tomography (PET) scanning (figure 1.1). As I explain my project on the history and anthropology of PET brain images, he interrupts to turn the question back to me:

PHELPS: What is it? If I am just an ordinary person and I ask you, “What is PET?”

DUMIT: It is a device that is like a CT [computed tomography] scanner but isn’t. With PET, you take some molecule or drug that you want to image—water or glucose, for example. You attach a radioactive isotope to it and inject it into your body, and what you image is where the tagged molecule or drug goes. You image the radioactivity through time; you capture it with a ring of detectors. What you get is an image of a slice and are able to reconstruct where the radioactivity is in one slice that gives a cross-sectional view of where something is through time. You can use it to find out where in the body and with what amounts the molecule is.

FIGURE 1.1. Principle of positron emission tomography (PET) using example of ¹⁸F-fluorodeoxyglucsoe (FDG) to image glucose metabolism in the human brain. (Michael E. Phelps 1991)

PHELPS: You know, another way to approach the explanation is to forget about PET initially and focus on the problem: That is to be able to take a camera and just watch. Inside the body is all this biology that we know is going on. You take food in, you eat it, and it becomes nutrients for your cells.

Your body looks like it is a physical, anatomical substance, but inside there are all kinds of cells that are metabolizing things, or moving around and doing things, signaling to each other. We’d like to be able to watch this action. That is the objective. You know the activity is there, and you’d like to be able to build a camera that can watch it. Well, one way to do that is first to say, “Well, if I was really little, I could go in there, move around, and watch those things.” But since you can’t go in there, you can send a messenger. So you do that. You say, “Well, I want to look at one portion of this.” So you take a molecule that will go and participate in that portion. The molecule will go through that process. You take that molecule and put a source on it that will emit back to you. So you inject it into your bloodstream, and it goes on this journey. It goes throughout your body with the flowing blood, and depending on that molecule, it will go into some organ that uses it. And you have a camera and can sit there now and watch that molecule, watch it go through the blood supply, go into the brain, go into the tissue of the brain, and actually go through the biochemical process. So you have a camera that allows you actually to watch some of that, watch the biology of the body. So that is really the objective. Forget about the particulars of the instruments. I know that inside this being there is a whole bunch of stuff going on, the biological activity of the body, the body’s chemistry. It gives me a way to watch that. This is really what PET does. It reveals to us something that we know is going on inside your body, but that we can’t get to. And it does it in such a way that does not disturb the biology of the body’s chemistry. This molecule is in such trace amounts that it—the body—goes on about its business. The molecule is apparent to us but transparent to the body.

DUMIT: Like an ideal participant observer.

PHELPS: It is an observer that doesn’t disturb you. That is, what happens would happen with or without that observer there. If you are an observer at the presidential conference and bother the president, then you distort what would have taken place had you not been there. But this molecule is given in such trace quantities that it makes no disturbance. Whatever happens would have happened whether you were there or not.

PET scans are generated by an incredibly complex, expensive, and deeply interdisciplinary set of techniques and technologies. An experimental PET brain scanner, including a requisite cyclotron to produce radioactive nuclides, costs about $7 million to purchase. A PET research project also needs the expertise of physicists, nuclear chemists, mathematicians, computer scientists, pharmacologists, neurologists. The aim is physiological: to gain information about the patterns of molecular flow in the body at specific places over a specific amount of time. PET scanning is the solution to the problem of how to follow a molecular substance like water, oxygen, sugar, or Prozac and see where in the body it goes, how much goes there, and whether it stays or circulates out of the area. With the use of a cyclotron, radioactive isotopes of one of the four common biological atoms (carbon, nitrogen, oxygen, and fluorine, the latter standing in for hydrogen) are substituted for the original atoms in the molecule of interest. This radiolabeled molecule functions exactly like the normal molecule. As it decays, the radioactivity is captured by the scanner and reconstructed in a map of the flow rate of the molecule. The result is a “picture” of the molecular flow in the body. This description is, of course, very general and overlooks many qualifications, assumptions, and variables in PET. This description is also not neutral. It will take the rest of the book to explain how each description of PET by different PET researchers is part of an ongoing attempt to define the meaning and purpose of PET and PET images, to make claims of invention and contribution, and to give ontological structure to the brain.

As an anthropologist, I have observed and interacted with various facets of this community for over 3 years, and I feel PET to be an incredibly important and increasingly powerful technique for producing images of living human brains. On the basis of my research, I have identified an area of PET signification that I believe is critical in debates over the roles of PET in the world today: the visual effect of PET brain images. By attending closely to PET images, I have chosen the most mobile aspect of PET experiments. These images travel easily and are easily made meaningful. Because they are such fluid signifiers, they can serve different agendas and different meanings simultaneously. While representing a single slice of a particular person’s brain blood flow over a short period of time, one scan can also represent the blood flow of a type of human, be used to demonstrate the viability of PET as a neuroscience technique, and demonstrate the general significance of basic neuroscience research.

In this book, we will be exclusively discussing PET brain images of mind and personhood, which are the most prominent PET images in the media. However, they are only one small part of PET’s usefulness. In addition to imaging the brain, PET is used clinically to image the heart, to help determine the ability of the heart to withstand a heart-bypass operation. PET is also extremely useful in whole-body and specific organ scanning to detect different cancer types by using a radiolabeled tracer that is attracted to metastatic and not benign tumors (e.g., it has been approved for Medicare and Medicaid coverage to help stage breast cancer).¹ PET is also used in neurosurgery to identify the precise location of epileptic foci. These other uses of PET are not subject to the same kind of critique we will be applying to PET brain-type images. This is because these other uses of PET can be calibrated directly with their referent. The heart, for instance, can be looked at surgically, and in comparison with the PET image one can learn exactly what signals regularly correspond with different tissue states. But in the case of mental activity and brain-types, there is no corresponding calibration.² In spite of decades of research into schizophrenia and depression, for example, there are no known biological markers for either one (Andreasen 2001), though with Alzheimer’s disease, we may be close. Thus in many cases, though we can say that PET accurately identifies the location of the radiolabeled molecule in the brain, we cannot verify that the additional oxygen flow through the frontal cortex is a symptom of schizophrenia.

Popular Brain Images

The brain scans that we encounter in magazines and newspapers, on television, in a doctor’s office, or in a scientific journal make claims on us. These colorful images with captions describe brains that are certifiably smart or depressed or obsessed. They describe brains that are clearly doing something, such as reading words, taking a test, or hallucinating. These brain images make claims on us because they portray kinds of brains. As people with, obviously, one or another kind of brain, we are placed among the categories that the set of images offers. To which category do I belong? What brain type do I have? Or more nervously: Am I normal? Addressing such claims requires an ability to critically analyze how these brain images come to be taken as facts about the world—facts such as the apparent existence and ability to “diagnose” of these human kinds. Behind our reading of these images are further questions of how these images were produced as part of a scientific experiment, and how they came then to be presented in a popular location so that they could be received by readers like us.

As readers, all of the processes of translation of facts, from one location and form of presentation to another, should be imagined when we critically assess a received fact. We should try to become as aware as possible of the people who interpret, rephrase, and reframe the facts for us (the mediators). We should also critically assess the structural constraints of each form of representation—peer review, newsworthiness, doctor presentations to patients (the media). In the case of the brain, these processes of fact translation are caught up in a social history that includes how the brain came to be an object of study in the first place, and what factors—conceptually, institutionally, and technically—were part of its emergence as a fact. When did it first become possible to think of the brain as having distinct areas that can break or malfunction? How and when did the brain come to have “circuits”? How did techniques and technological metaphors like telegraphs and electricity make it possible to pose the problem of brain imaging? In turn, what disciplinary and institutional funding mechanisms were available to make the questions posed answerable?³ Some human kinds that we are starting to take for granted, such as “depressed brains,” require attending to broader social and institutional forces in order to understand how it is that we look to the brain for an answer.

An early appearance in the popular media of brain images can be seen in a 1983 article in the fashion magazine Vogue (see Plate 1). Entitled “High-Tech Breakthrough in Medicine: New Seeing-Eye Machines . . . Look Inside Your Body, Can Save Your Life,” the piece was accompanied by a simple graphic: three similar, oval-like blobs each filled with dissimilar patterns of bright colors (Hixson 1983). Above each shape is a white word in bold font standing out from the black background: NORMAL, SCHIZO, DEPRESSED. The article does not need to be read to be understood. The juxtaposition of words and images brings home quite forcefully that the three colored ovals are brain scans, and that the three brains scanned are different. These images insist that there are at least three kinds of brains. Presumably, these brains belong to different people—who are three different kinds of persons because their brains are not the same. The cultural and visual logics by which these images persuade viewers to equate person with brain, brain with scan, and scan with diagnosis are also the subject of this book.

Facing the brain images in Vogue, there appears to be something intuitively right about a brain-imaging machine being able to show us the difference between schizophrenic brains, depressed brains, and normal ones. This persuasive force suggests that we ignore the category question of whether three kinds of brains means three kinds of people. How could there not be a difference in these three kinds of brains if there are such differences in the three kinds of people, schizophrenics, depressed, and normals? And after seeing the different brain images, how could one not perceive a difference between these three “kinds” of people? The images with their labels are part of the process of reinforcing our assumptions of difference and making them seem obvious and normal. Rationally, we may still remember that this is a category mistake, a substitution of a small set of scan differences for the universal assumption of differences in kind. Thus, the effect of such presentation of images is to produce an identification with the idea that there is a categorical difference between three kinds of humans that corresponds essentially to the three kinds of brains—or brain-types. So we see, too, that in our encounters with brain images we come face-to-face with an uncertainty regarding our own normality and “kinds” of humans that we and others are. Alongside the social and institutional components of brain-fact production, we must face this question of how cultural identification and intuition coincide with these representations of reality so that we are persuaded to take them as true.

What does it mean to encounter “facts” like brain images in popular media? How are “received facts” like these used in other contexts and by other people—in courtrooms, in doctors’ offices, before Congress? The labels and stories accompanying the image may be far removed from the careful conclusions of the original scientific journal article, and the news story may include comments deemed “indefensible” by the original researchers. Nevertheless, popularization is not a simple one-way process of corrupting by dumbing down a scientific message. In many cases, the researchers will continue to participate with journalists in constructing these stories because there are not many other ways to get the facts out. Publicity in all of its forms, with all of the transformations it conducts on the facts, is how we come to know facts about ourselves (Myers 1990; Nelkin 1987; Prelli 1989). In any case, like scientists, as scientists, we supplement our knowledge with facts, knowing full well that the facts almost always have qualifications. This does not stop us from incorporating these facts, however, and from assuming them and acting on them (Hess 1997; Martin 1994).

Many researchers have pondered how risks, danger, and stereotypes (notions of human kinds) are best explained in cultural terms. Ranking uncertain dangers, acting in the face of contradictory facts, and imagining human kinds and attributes are culturally and historically variable practices (Douglas and Wildavsky 1982; Gilman 1988). Borrowing a term from psychology and semiotics, we can characterize our relationship to culture as identification. Rhetorician Kenneth Burke defined identification as the “ways in which we spontaneously, intuitively, even unconsciously persuade ourselves” (Burke 1966, p. 301). As in analyses of ideology, the rightness of facts seems to emerge from our own experience.⁴ This notion of self-persuasion helps us keep in mind both the persuasive action of received facts (e.g., from a magazine) and the form...