1 The Emergence of the Neurosociety Brain Imaging: Peering into Bertino's Brain As a first step in appreciating the impact of social neuroscience, it helps to understand the power of imaging techniques to provide a window into events happening within the brain. The earliest techniques capable of revealing the brain's inner processing carried a definite risk of injury and sometimes even death. Consequently, they were restricted to patients suffering from various brain diseases. As a result of this emphasis on disease, we presently know more about the functioning of abnormal brains than we know about normal ones. As a neurologist, I'm especially aware of this paradox. Ask me about the brain dysfunctions associated with strokes or autism or even some forms of learning disability and I can explain the difficulties in more detail than you probably want to hear. But ask me how the brain of a genius differs from that of his or her less intellectually gifted counterparts and the explanation isn't going to take long at all. Not that we can't learn a lot about the normal brain on the basis of studying abnormal brains.
Even a study of the diseased brain often provides some helpful insights toward furthering our understanding of the normal brain. My favorite example of this comes from the observations of the late-nineteenth-century Italian experimenter Angelo Mosso. In the course of his research Mosso encountered a peasant, Bertino (no last name is recorded), who several years earlier had suffered a head injury severe enough to destroy the bones of the skull covering his frontal lobes (located immediately behind the forehead). The resulting opening, covered only by skin and fibrous tissue, provided Mosso with a window through which he could directly observe the pulsations of Bertino's brain. Similar pulsations can be observed in a newborn baby during the first few weeks of life prior to the growth and fusion of the skull bones. When the baby cries or strains, the pulsations increase; when the baby sleeps, the pulsations subside. One day when Mosso was observing the pulsations he noticed a distinct increase in their magnitude coincident with the ringing at noon of the local church bells. At this point Mosso, in an act of inspiration, asked the peasant if the ringing of the Angelus reminded him of his obligation to silently recite the Ave Maria.
When Bertino responded yes, the pulsations increased again. Intrigued at this sequence, Mosso asked his subject to multiply eight by ten. At the moment Mosso asked the question, the pulsations increased and then quickly decreased. A second increase occurred when Bertino responded with the answer. From this simple but elegant experiment Mosso correctly concluded that blood flow in the brain could provide an indirect measurement of brain function during mental activity. Inspired by Mosso's findings with Bertino, students of the brain during the early and middle parts of the twentieth century developed more accurate techniques for measuring blood flow and metabolism in the human brain. For instance, dyes and radioactive substances injected into the arteries leading to the brain help pinpoint the relevant structures responsible for vision, movement, and sensation. But one important limitation lessened the usefulness of these probes into the brain's functioning: All of them were intrusive, dangerous, and on occasion fatal.
While undergoing one of the tests the subject could suffer a stroke, blindness, even death. Fortunately, that problem is now a thing of the past thanks to the safety of newer techniques, which carry little risk. Current imaging techniques are often described using a kind of alphabet soup terminology: "The patent's CAT was normal but a contrast-enhanced MRI showed a small SOL in the frontal lobes later confirmed by PET." Such a sentence isn't very helpful to anyone other than a doctor or someone else trained in the use of this off-putting terminology. In place of acronyms and obfuscation, here's a simplified way of thinking about brain imaging. Basically, imaging techniques are either structural or functional. If you've ever undergone a CAT (shorthand for computerized axial tomography) scan or an MRI (magnetic resonance imaging) scan, the doctor ordering that scan was interested in capturing an image of your brain's structure. Perhaps your doctor thought that you might have suffered a stroke or developed a brain tumor.
Tumors and strokes can be recognized by the alterations that they bring about in normal brain anatomy. CAT scans and MRI scans provide a picture of those alterations. Functional imaging, in contrast, depicts what the brain is doing over a certain period of time ranging from seconds to minutes. All of the functional imaging techniques (functional MRI, or fMRI, PET scans, and SPECT scans are the most common) are based on a simple principle: Brain activity leads to changes in blood flow (as with Bertino), electrical discharges, and magnetic fields. As I'm writing this sentence an fMRI would show increased activity in those areas of my brain associated with thought (especially the frontal areas), vision, and the movement of my fingers across the keyboard of my word processor. An fMRI of your brain would show activation of the visual areas, which process the words on this page, along with the frontal areas, which grasp the meaning of the sentences, and the motor areas, which control the movement of your hand as it reaches up and turns the page. Ideally, an imaging technique should accurately pinpoint both the structure and the function, the "where" and the "when" of brain activity. On the "where" scale currently available techniques are accurate within millimeters.
But the "when" determinations leave a lot to be desired. The temporal resolution of PET (positron-emission tomography) scans is tens of seconds or even minutes. The most technologically advanced fMRI does a bit better, with a resolution on the order of a tenth of a second. But even that is woefully insufficient as a measurement of how rapidly things are happening in the brain. To give you some perspective, consider that an activation originating in the motor neurons of your brain takes only about 150 milliseconds (thousandths of a second) to reach the muscles of your forefinger when you press a doorbell. Or consider that you can accurately identify an object that suddenly enters your field of vision within a few hundred milliseconds. In short, in order to establish meaningful relationships between our mental lives and events occurring in our brain, it is important to achieve a temporal resolution of milliseconds. But here's the sticky point.
The most accurate technique for doing that involves inserting a tiny needle into the brain and then threading it into a single brain cell. While Dr. Strangelove might consider this invasive, potentially risky procedure acceptable in healthy brains, most others would consider it totally unacceptable. To further appreciate the challenges in depicting brain activity, think back for a moment to the Heisenberg uncertainty principle in quantum physics: You cannot simultaneously determine the position and the velocity of a particle because of the effect created by the act of measurement ("The more precisely the position is determined, the less precisely the momentum is known in this instant, and vice versa," Heisenberg wrote in 1927). Neuroscientists also encounter a kind of uncertainty principle when studying the brain: They have to choose between achieving either an accurate positional fix (within millimeters) or an accurate temporal fix (within fractions of a second). So far no single technique exists that can provide both; only the use of multiple techniques can make possible the desired integration of spatial and temporal information. To further complicate matters, the brain's operation can't be understood by measuring one neuron at a time; instead, we must focus on thousands of neurons firing together to form "circuits." Everything You'll Need to Know About the Brain Although a lot will be said about the brain in this book, a detailed knowledge of that incredibly complex structure won't be required.
Indeed, all that you'll need is to remain mindful of two useful distinctions. The first is between controlled and automatic processes. As an example of a controlled process, recall the last time you worked on your income tax or balanced a budget. Your thoughts followed each other in a sequential manner; you remained consciously aware of what you were doing; if requested, you could explain your thought processes to somebody else. In addition, if you continued your efforts long enough you were likely to experience fatigue or boredom. As an example of an automatic process, think back to the last time you took an immediate dislike to someone you had just met. Or an occasion when you discerned a hint of condescension in a coworker's voice as she explained a new procedure to you. Or an afternoon when you paused while walking down a street and looked appreciatively as an attractive person passed by.
If asked at the time about such occurrences, you would have come up with various explanations to justify your impressions, but these would only have been guesstimates. That's because with automatic processes things just happen. You can't really explain why you disliked the new acquaintance while everybody else liked him. Nor why you were the only person who perceived condescension in the coworker. Nor why other people.