American Scientist

TOUCHING A NERVE: The Self as Brain. Patricia S. Churchland. 304 pp. W. W. Norton, 2013. $26.95.

We are what we are because our brains are what they are. That connection between self and brain—obvious yet endlessly elusive—lies at the foundation of some of life’s most profound questions. What part of our body thinks our thoughts and binds us to morals? Is there a soul? An afterlife? How do we know what is real? Addressing such matters requires taking an outside view of an organ that we are all forced to experience from the inside. Making headway toward answers requires thinking simultaneously like a philosopher and a neuroscientist.

Fortunately, Patricia Churchland is both: a philosopher turned neuroscientist, who once taught a course called neurophilosophy to undergraduates at the University of California, San Diego. She begins her new book by walking the reader through her three-point organizational logic. This section is not a page-turner, but it sets the foundation for all that follows. Point one: Integrating reality into our state of mind allows us to avoid danger (for example, by preventing disease) and improve our world (by finding cures). Two: Wishful fantasy may be enjoyable, but it is temporary. Conversely, knowledge of what is true and real may be repugnant, but facts will triumph, as Churchland illustrates through the case of Galileo and the Catholic Church. Third: We can control how we use science. An excess of knowledge does not hurtle us to Armageddon.

Touching a Nerve is not a neuroscience textbook; it is accurate, without the burden of excessive scientific detail. Instead, Churchland crafts a big-picture discussion of how the brain engineers human consciousness, thought, and behavior, presenting the underlying science in a conversational tone that’s lively and engaging. She aims to make science relevant, exciting, accessible.

When Churchland explores the origins of moral behavior, she lays out the thesis that the mammalian brain is wired for self-care and the care of others. And yet, as she notes, the people we love often provoke us to anger. Paradoxically, an individual can shift from a state of mind we call love to one that allows him or her to commit an “honor killing.”

Churchland devotes another chapter to aggression and sex, digging deeply as she engages some enduring mysteries. What is the lure of hatred and aggression? Why are we so predisposed to frame interactions as “us versus them”? Churchland outlines her intriguing belief that hate and aggression are linked to the brain’s sensation of pleasure. (Why else would gossip be so enjoyable?) This chapter is an interesting sausage of overlapping topics that could easily fill many more pages. Here the author mixes her personal experience with science, an effective approach for such potent subject matter. The reader almost feels part of the conversation.

I was initially apprehensive when I got to the part of the book where Churchland takes on the contentious topic of “testosterone poisoning.” The term suggests that iconic masculine behavior may be ridiculed as a hangover from prehistory. Would Churchland be condescending here, I wondered, presenting feminine traits as more progressive and enlightened, even a new unisex norm? No. Instead, she gives a balanced view of why so much of human behavior extends from the deep biological roots of distinctly different female-brain and male-brain behaviors.

Churchland explains that the brain makes mating and survival in a hostile world possible, and doing so requires it to be energized and cunning. A state of aggression is exciting, and it reinforces the collective strength of bonding within the social group or pack. Deep roots of aggression can be found in today’s gang violence and is ritualized in team sports. Yet baiting and gossip are forms of aggression, too. Whether violence is physical or verbal, our brains do link it to pleasure.

As this section of the book delves into the brain anatomy and chemistry underlying sex and aggression it becomes a real page-turner. Here Churchland explores charged issues such as how the balance between estrogen and progesterone in females modulates whether the brain will be feminized or masculinized, and how levels of testosterone influence male-brain sex and aggression. The chemistry is not simple, but the author highlights the impact of an assortment of key factors, such as different ratios of testosterone and stress hormones (cortisol, for example) and variable expressions of neurotransmitters and neuromodulators, including serotonin, dopamine, nitric oxide, and vasopressin.

Churchland also brings plainspoken reason to what is often called gender identity, which decades of science have not been particularly effective in illuminating for large segments of society. Simply put, gender is not as simple as XX and XY. Chemicals such as gonadotropin-releasing hormone can cause a disconnect between a person’s gonadal gender and brain gender—hence, men who feel trapped in a woman’s body and women who feel trapped in a man’s. Normal is a far more elusive concept than once thought.

In the final chapters of Touching a Nerve, Churchland returns to more philosophical territory. After taking on mating, aggression, and sexual identity, perhaps it is logical that she progresses to a discussion of genocide and war, exploring the claim that humans are genetically predisposed to war. Ultimately she exposes it as a fallacy, viewing the argument as an excuse for bad behavior. Self-control is necessary for making good decisions, she argues, and neuroscience provides a general, if not yet well-resolved, understanding of how connectivity between different brain structures underlies self-control.

Churchland moves on to address free will, crime, intent, and punishment. The interpretation of a person’s intent and state of mind lies at the core of determining if someone is criminally responsible for a socially harmful act. She discusses the attempted murder of President Reagan as a product of John Hinckley’s obsession with Jodi Foster, explaining how that fixation produced a collision between common sense, the legal matter of volition, and the weight of scientific evidence.

Toward the end, Churchland explores hidden cognition and the unconscious self and wraps up this very entertaining book with a discussion of the conscious life. Her closing discussions of warfare, criminal law, justice, and free will may stray beyond the boundaries of rigorous science, but Churchland’s brand of neurophilosophy serves a great need: It provides a framework for objective reflection on matters of real importance in today’s world.

Richard Wiggins is editor of Ingenuity: Journal of Student Engineering and Science Research, a Sigma Xi online publication currently under development. He previously served as the anatomy department chair at the West Virginia University School of Medicine and director of the neurotoxicology division of the U.S. Environmental Protection Agency.