Campus Connection

Issue date: 9/15/09 Section: Perspectives

Human nature has been a favorite focus of deep philosophical thought since the earliest of times. The phrase, "Know thyself," inscribed at the entrance of the Temple of Apollo at Delphi, which dates back to 4th century B.C., is early evidence of the uniquely human fascination with ourselves. And over the centuries questions of human nature have increasingly overlapped with questions of the human brain. Many of us know the phrase coined by the 17th century philosopher Rene Descartes: "I think, therefore I am." But perhaps we are a little less familiar with what prompted him to utter those famous words. As he delved into the idea of doubt, Descartes came to the conclusion that whereas he could not be certain of the existence of his body, he could be certain of the existence of his mind, simply by the fact that he had the capacity to think -hence his realization of "I think, therefore I am." Thus, he built upon the philosophy of dualism, formulating the concept of a mind-body dichotomy, where the mind interacts with, but exists separate from the body, and thus the brain. This was a powerful idea and one that remains prevalent in our society today. After all, not many of us actually consider the emotions we experience to be preprogrammed by our brains. Instead, we (including neuroscientists, like the graduate student I once engaged in a discussion on this subject, who asked, "but what about the intangibles, like love?"), prefer to believe that what we feel and how we think are phenomena that can't just be explained away by cells, molecules, and genes. Nonetheless, some of today's cognitive scientists are fighting the latter instinct in favor of the former point of view, which is perhaps a sign that the days of Cartesian dualism may be numbered. One example is a recent study in the journal Science that investigated the influence of genes on cognitive abilities. Ten sets of siblings, each consisting of a pair of male identical twins and a non-twin brother had their brains scanned using functional magnetic resonance imaging (fMRI) while they performed a memory task. The siblings were asked to memorize a short span of digits. Then they were then given a "distraction" task to disrupt that memory: either a simple arithmetic problem (2 + 4 = 7, yes or no?) or instructions to categorize a picture of an object. They were then shown a number and asked if it was among the numbers in the memory task. The team, led by Jan Willem Koten Jr. of RWTH Aachen University in Germany, found that the men used two different strategies to retain the digits in their memory. Some used brain areas associated with language while others used the visual-spatial memory system, something like counting on fingers. They found that the memory task took longer when the language pathways were employed. But more importantly, they noted that the pairs of twins (sharing 100% of their genes) used the same strategy more often than their non-twin brothers (sharing only 50% of their genes), indicating the presence of a strong genetic component to thought processes. Normally, during fMRI studies, the data on brain activation is averaged across groups. But the Koten study suggests that such a strategy can overlook individual differences in how brains accomplish a task. More importantly, by not appreciating the variability between individuals, we are likely missing an opportunity to learn about the relationship between genes and brain activity. This idea, that the genetics of the brain predetermine the processes of the mind, might be very anti-Cartesian, but it has been catching on in the neuroscience community for some time. Eric Kandel, a Columbia University neuroscientist and Nobel laureate, noted (in one of my all-time favorite quotes!): "What we commonly call the mind is just a set of operations performed by the brain." He elaborated on this point in his book, In Search of Memory: The Emergence of a New Science of Mind, where he argued that we should reconsider the word "mind" not as a noun but as a verb. The brain does something - "to mind" is the job of the brain. To refer to the mind-as virtually all of us do-is to imply that there exists something separate from the brain that allows us to remember numbers or, if we're lucky enough, to fall in love. But perhaps, that separation does not actually exist. Understandably, many people are uncomfortable with the idea that our genes are in part responsible for how our brains function; that how smart, violent, ambitious, shy, benevolent, or republican we are may be beyond our control. But such concerns shouldn't discourage us from studying whether or not-or how-genes are involved. In fact, this knowledge can only serve to enhance our understanding of ourselves, which is precisely what Descartes strove to do. Now, the only question is: who should take the lead on this research, our scientists our philosophers?

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