From the recent announcement of President Obama's BRAIN Initiative to the Technicolor brain scans ("This is your brain on God/love/envy etc") on magazine covers all around, neuroscience has captured the public imagination like never before.
Understanding the brain is of course essential to developing treatments for devastating illnesses like schizophrenia and Parkinson's. More abstract but no less compelling, the functioning of the brain is intimately tied to our sense of self, our identity, our memories and aspirations. But the excitement to explore the brain has spawned a new fixation that my colleague Scott Lilienfeld and I call neurocentrism -- the view that human behavior can be best explained by looking solely or primarily at the brain.
Sometimes the neural level of explanation is appropriate. When scientists develop diagnostic tests or a medications for, say, Alzheimer's disease, they investigate the hallmarks of the condition: amyloid plaques that disrupt communication between neurons, and neurofibrillary tangles that degrade them.
Other times, a neural explanation can lead us astray. In my own field of addiction psychiatry, neurocentrism is ascendant -- and not for the better. Thanks to heavy promotion by the National Institute on Drug Abuse, part of the National Institutes of Health, addiction has been labeled a "brain disease."
The logic for this designation, as explained by former director Alan I. Leshner, is that "addiction is tied to changes in brain structure and function." True enough, repeated use of drugs such as heroin, cocaine, and alcohol alter the neural circuits that mediate the experience of pleasure as well as motivation, memory, inhibition, and planning -- modifications that we can often see on brain scans.
The critical question, though, is whether this neural disruption proves that the addict's behavior is involuntary and that he is incapable of self-control. It does not.
Take the case of actor Robert Downey, Jr., whose name was once synonymous with celebrity addiction. He said, "It's like I have a loaded gun in my mouth and my finger's on the trigger, and I like the taste of gunmetal." Downey went though episodes of rehabilitation and then relapse, but ultimately decided, while in the throes of "brain disease," to change his life.
The neurocentric model leaves the addicted person (Downey, in this case) in the shadows. Yet to treat addicts and guide policy, it is important to understand how addicts think. It is the minds of addicts that contain the stories of how addiction happens, why they continue to use, and, if they decide to stop, how they manage. The answers can't be divined from an examination of his brain, no matter how sophisticated the probe.
It is only natural that advances in knowledge about the brain make us think more mechanistically about ourselves. But in one venue, in particular - the courtroom - this bias can be a prescription for confusion. The brain-based defense ("Look at this fMRI scan, your Honor. My client's brain made him do it.") is now commonplace in capital defenses. The problem with these claims is that, with rare exception, neuroscientists cannot yet translate aberrant brain functions into the legal requirements for criminal responsibility -- intent, rational capacity and self-control.
What we know about many criminals is that they did not control themselves. That is very different from being unable to do so. To date, brain science cannot allow us to distinguish between these alternatives. What's more, even abnormal-looking brains, have owners who are otherwise quite normal.
Looking to the future, some neuroscientists envision a dramatic transformation of criminal law. David Eagleman of the Baylor College of Medicine's Initiative on Neuroscience and Law, hopes that "we may someday find that many types of bad behavior have a basic biological explanation [and] eventually think about bad decision making in the same way we think about any physical process, such as diabetes or lung disease."
But is this the correct conclusion to draw from neuroscience? If every troublesome behavior is eventually traced to correlates of brain activity that we can detect and visualize, will we be able to excuse it on a don't-blame-me-blame my-brain theory? Will no one ever be judged responsible?
Eagleman's way of thinking represents what law professor Stephen Morse calls the "psycho-legal error," our powerful temptation to equate cause with excuse. Morse notes that the law excuses criminal behavior only when a causal factor produces an impairment so severe that it deprives the defendant of his or her rationality. Bad genes, bad parents, or even bad stars are not an excuse.
Finally, what are the implications of brain science for morality? Although we generally think of ourselves as free agents who make choices, a number of prominent scholars claim that we are mistaken. "Our growing knowledge about the brain makes the notions of volition, culpability, and, ultimately, the very premise of the criminal justice system, deeply suspect," contends biologist Robert Sapolsky.
To be sure, everyone agrees that people can be held accountable only if they have freedom of choice. But, there is a longstanding debate about the kind of freedom that is necessary. Some contend that we can be held accountable as long as we are able to engage in conscious deliberation, follow rules, and generally control ourselves.
Others, like Sapolsky, disagree, insisting that our deliberations and decisions do not make us free because they are dictated by neuronal circumstances. They say that, as we come to understand the mechanical workings of our brains, we'll be compelled to adopt a strictly utilitarian model of justice in which criminals are "punished" solely as a way to change their behavior, not because they truly deserve blame.
Although it's cloaked in neuroscientific garb, this free-will question remains one of the great conceptual impasses of all time, far beyond the capacity of brain science to resolve. Unless, that is, investigators can show something truly spectacular: that people are not conscious beings whose actions flow from reasons and who are responsive to reason. True, we do not exert as much conscious control over our actions as we think we do. Every student of the mind, beginning most notably with William James and Sigmund Freud, knows this. But it doesn't mean we are powerless.
The study of the brain is said to be the final scientific frontier. Will we lose sight of the mind, though, in the age of brain science? While the scans are dazzling and the technology an unqualified marvel, we can always keep our bearings by remembering that the brain and the mind are two different frameworks.
The neurobiological domain is one of brains and physical causes, the mechanisms behind our thoughts and emotions. The psychological domain, the realm of the mind, is one of people -- their desires, intentions, ideals, and anxieties. Both are essential to a full understanding of why we act as we do.