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Rosenberg, Roger N. MD

Book Review: Infobytes

Dr. Rosenberg is the Zale Distinguished Chair and Professor of Neurology at the University of Texas Southwestern Medical Center in Dallas.

The Ethical Questions of Our Times through the Prism of Neuroscience

225 Pages • Dana Press • 2005

When should we call an embryo or a fetus “one of us?” What is normal brain aging, and should we simply aspire to live longer, no matter what our brain state might be? Should we be free to make a better brain by means of genetics, pharmacology, and training? What do more powerful brain imaging technologies mean for privacy and for self-incrimination?

These questions and debates are addressed in The Ethical Brain, a new book by Michael S. Gazzaniga, PhD, Director of the Center for Cognitive Neuroscience at Dartmouth College, a member of the President's Council on Bioethics, and a founder of the discipline of cognitive neuroscience.

Gazzaniga first became prominent through his research in the California Institute of Technology laboratory of Roger W. Sperry, who won the Nobel Prize in Medicine in 1981 for his work on split brain studies as a result of corpus callosotomy in the primate. Sperry and Gazzaniga showed that in monkeys and humans, when the corpus callosum was cut, each cerebral hemisphere operated independently and was unaware of perceived experiences in the contralateral hemisphere.

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Gazzaniga has continued this legacy of brilliance in writing The Ethical Brain. In the initial section, “Life-Span Neuroethics,” he comes to grips with the fierce debate regarding when an embryo shows evidence of human life. He elicits questions: Up to what time point is it ethical to perform therapeutic cloning by nuclear transfer? When is it necessary to attribute the same moral status to a human embryo as is attributed to a newborn baby or to any living human? The development of embryo stem cell research depends on a resolution of these issues and many firm, deeply felt, divergent and polar positions have been taken.

Gazzaniga argues that before the fourteenth day of development, the embryo has no discernable brain. The nervous system does not develop until after that time and thus he argues that “the fourteen-day cutoff employed by researchers to be a completely acceptable practice.” His bold and highly reasoned position on this matter keeps the reader riveted to the debate.



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“Better Brains through Genes” discusses the ethics of genetic enhancements to increase intelligence, or specific behavioral advantages – from math to musical skills – through eugenics by introducing these behavioral-enhancing genes during embyrogenesis.

Through pre-genetic screening, neurological genetic diseases could be detected and treated by gene therapy or, if necessary, the pregnancy terminated, Gazzaniga contends. Eugenics would be moral and ethical if these techniques were applied voluntarily and could be shown to improve the welfare of society at large.

Clearly, this is a contentious perspective that brings into focus the murderous eugenics of Nazi Germany, the rights of the unborn, and the dehumanizing of human dignity. Gazzaniga tells it forthrightly and lets the reader balance all the facts. Is it ethical to create a smarter brain? The worry is that a smarter brain may be programmed in subtle ways to be an impersonal brain and thus lose or diminish our precious human legacy for sensitivity, humility, and compassion.

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In the highly provocative section, “My Brain Made Me Do it,” Gazzaniga lays out the neuroscience behind the brain's evolutionary development of highly efficient analytical systems for logical deciphering and complex problem solving. The brain automatically integrates these analytical systems. However, we have free will, he points out, to make moral and ethical decisions using the data and answers provided by these systems.

He writes: “Brains are automatic but people are free” and “the brain is determined, but the person is free.”

Gazzaniga concludes that deterministic arguments that manipulate neuroscience and thereby diminish human responsibility have no place in the courtroom. Is Gazzaniga correct in this position? It becomes more complicated when the arena of brain incrimination is introduced.

Gazzaniga points out that neuroimaging and evoked potential studies can detect a person's disposition to a belief or knowledge of an event. Involuntary self-incrimination by reading brain regional activations for truth-telling, lying, or deception is an active area of neuroscientific research – and the ethical dilemmas that emerge by potentially infringing on a person's privacy and constitutional rights are vividly depicted.

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Finally, in “Toward a Universal Ethics,” Gazzaniga 's neuroethical philosophy and scholarship come together. He emphasizes that the willingness to act on a moral belief is a direct result of an organic process: the emotional part of the brain becomes activated in considering the moral question.

Further, he argues, that our ‘mirror neurons’ are monitoring the behavior of others as their ‘mirror neurons’ are monitoring our behavior. We seek to be altruistic and moral because these behaviors have selective and survival value. Ethical behavior has as its substrate the unconscious mechanisms we evoke or choose not to evoke by free will “that keeps our species, over the long haul, from destroying itself.”

Gazzaniga has written a seminal and brilliant book about the neurological basis of human ethical behavior. It is remarkably clear and clean in its exposition of ideas, and its scientific impact will be appreciated far into the future.

©2005 American Academy of Neurology