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Does Brain Equal Behavior? Experts Offer Diverging Perspectives

Despite some divergent perspectives on the roots of human behavior, two experts — a neuroscientist and a neuroethicist — agreed at a AAAS event that humility is in order when scientists study or attempt to manipulate the human brain. This is true now more than ever as advances in research outrace society's ability to resolve related questions of free will, ethics and morality, they said.

The two squared off in friendly discussion of the topic "Did My Brain Make Me Do it? Neuroscience and Morality," at an 11 December event at AAAS.

The speakers indicated they would present differing interpretations of the latest findings in order to stimulate thinking on the human brain, which one called "the single most complex thing we know about in the universe," and on related issues that entail philosophy and metaphysics and which have eluded resolution over the centuries. The session was presented by the AAAS' Dialogue on Science, Ethics and Religion.

Anthony-Samuel LaMantia, director of the George Washington Institute of Neuroscience, and professor in GWU's Department of Pharmacology and Physiology, said that research shows an absolute equivalence between the structure of a brain and that individual's behavior, especially complex behavior. "Brain equals behavior," he declared.

Not so fast, countered Paul Root Wolpe, director of the Center for Ethics at Emory University, professor of bioethics and Distinguished Research Chair in Jewish Bioethics, and a senior bioethicist with NASA. "Insofar as brains generate behavior, it's not through structure alone," he said.  "We fill brains with stuff [through learning], and the stuff we fill brains with is profoundly important in terms of how we tend to behave."

For his talk, LaMantia first redefined his vocabulary. Instead of "moral" and "immoral," which he said were "far too much for a simple neuroscientist to consider," he preferred "adaptive" — i.e. of benefit to an individual — and "maladaptive," because those terms are "more biological."

Research shows that brains can "go bad," tending toward maladaptive behavior, in two main ways, he said:  First, they can malfunction after years of working nicely, and second, they can be "built wrong" from the outset.

His Exhibit A was the celebrated case of Phineas Gage, a Vermont railroad construction foreman. On Sept. 13, 1848, an iron tamping rod, almost 4 feet long, shot through Gage's eye and out the top of his head.  The accident transformed him from "upstanding" to mean, profane and "at times pertinaciously obstinate." To his friends, he was "no longer Gage." The case altered thinking on the role of the brain in personality and behavior.

More recently, John Grimsley, a pro football linebacker, died in 2008 at age 45 after enduring multiple concussions. Boston University researchers, studying his donated brain, found that Grimsley had chronic traumatic encephalopathy — a disease associated with memory loss, aggressive behavior, depression and dementia — which has been recognized as an issue in boxers as well as football players.

Genetics can be crucial in brain malfunction. In fact, LaMantia suggested, "genes equal brain equal behavior." About 70 percent of the human genome (some 14,000 genes) is deployed in the brain.  And yet just one mutant gene can cause early onset dementia.

The second category — brains badly constructed — is more subtle and "far more challenging," LaMantia said. His laboratory has studied a common disorder caused by the deletion of a small piece of chromosome 22. One hundred percent of individuals with this mutation will exhibit some form of autism, ADHD, schizophrenia or anxiety disorder, he said. It therefore provides "the strongest genetic association we have with this spectrum of behavioral difficulties."

Researchers confirmed the linkage by introducing the mutation into mice. The animals showed the same physical abnormalities as those seen in humans, and they exhibited diminished ability to learn how to snag a food reward.

To "overlay" such practical advances onto society's ongoing struggles with issues of morality and free will, the field of neuroethics has emerged, with Wolpe as one of its pioneers.  He warned against "hubris." Consider the history of attempts to diagnose and change the brain, he said. "It's a pretty sad one" with many "horrific activities" such as forced lobotomies.  "Behind it always was a vision of . . . how we need to change the brain so that people will conform to some moral vision."

Wolpe challenged LaMantia on several points, including:

  • The notion that "moral" equals "adaptive." Moral behavior can be maladaptive, Wolpe said.  Say you live under a dictator who threatens to execute you if you don't do something you consider reprehensible. Behaving "morally" will get you killed.
  • The importance of genes: Do we really believe our 20,000 genes could "micro-control" the 215 trillion synaptic connections we have at birth, Wolpe wondered.  "It doesn't make a lot of sense." He said research on identical twins supports him on this, by showing that influences beyond their genes can create profound differences between their brains.

Wolpe also questioned controversial claims, highlighted at a recent meeting of the International Neuroethics Society in this same building, that neurons firing in a person's cerebral cortex might command his actions "preconsciously," a few hundred milliseconds before he consciously "decides" and that therefore he is not responsible for those actions. Wolpe said this is merely a new twist on an ancient question and "the issue of responsibility remains the complicated problem it has always been."

Wolpe has long been dissatisfied with the language of neuroscience, he said.  "If we believe that 'my brain' equals 'myself,' then saying 'my brain' is like saying 'brain's brain.'" This remains a deep philosophical conundrum for neuroscience, he said. If you ask the question, "'Did my brain make me do it?' then who is the 'me' that has the brain?"

In the end, the speakers agreed that deciphering what mechanisms account for complex behaviors remains daunting, and that ultimately the explanations must take into account both the brain and the remarkable range of individual human behaviors that, for now, defy easy understanding.