Monday, November 21, 2005

Neurobiology of human values I


Modern brain science has made a big impact on numerous issues, not the least on health care. The invention of psychopharmacological agents was the first break-through in human history in the treatment of psychiatric diseases.

The consequences of neuroscience may, however, be felt most at all in our self-conception, in how we view human nature. A very clear example of how profound investigations into the brain have upset very deep seated convictions about human nature is the research started by Thomas Willis and his Oxford circle in the 1660’s. By empirically examining both human and animal brains Willis demonstrated that not only bodily, but also cognitive functions, were governed by physical (albeit, at that time, still unknown) processes located in the grey matter of the brain. This conclusion effectively broke with a more than 2000 year old psychological model where bodily and cognitive function were commanded by different parts of the soul – most dramatically in Descartes’ philosophy of mind, where the bodily functions were imagined to be controlled by wholly material forces, whereas “the mind” were seen as non-material. In fact, it is fair to say that this break in our self-image was so powerful that we haven’t really come to terms with it yet. The story of Willis’ groundbreaking work is told masterfully in Carl Zimmer’s informative and very entertaining book The Soul Made Flesh.

In many ways, though, the revolution of Willis pales beside the neuroscientific results obtained in the last 30 years. We are now on the brink of understanding how the very brain processes Willis could only speculate about actually work. Some processes, early vision and memory consolidation for instance, are already quite well understood, even on a molecular level. And the invention of brain imaging techniques – PET, fMRI, MEG, etc. – has made it possible for brain scientists to start digging into even more mysterious and opaque faculties of the human brain such as decision-making, future planning, mathematical reasoning, and language…In short, all the higher-order cognitive faculties we consider the defining and unique traits of the human species. Already, this research is turning out some rather unexpected surprises. Consider, for example, how studies of human economic decision-making have shown the reward and punishment system – the basal ganglia, nucleus accumbens, amygdala, OFC, and other structures – to be critically implicated. Processes in these structures are highly dependent on neurotransmitters such as dopamine and serotonin. As it turns out, these molecules play much the same role in rat and monkey striatum, with dopamine, for instance, contributing to reward-prediction processes. Thus, behaviour such as economic wheelin-n-dealin, hitherto considered a strictly human ability, setting us apart from the rest of the animal kingdom (perhaps even elevating us to a superior, non-animal level of the great chain of being...), has at least some root in neuronal mechanisms that have been around for millions of years and which we share with other animals.

Throughout the last century economic behaviour were explained through mathematical models – utility functions and game theory. Now this approach is being turned on its head…or actually inside the head, as it were! Economics is slowly becoming neuroeconomics. And, similarly, philosophy is becoming neurophilosophy, sociology is becoming social neuroscience, aesthetics is becoming neuroaesthetics, etc., etc. This is perhaps next big revolution brought about by the neurosciences: putting the humanistic sciences on a biological footing, exchanging cultural analysis for neuroscientific experiments!

The coming days I will post discussions of a new book that epitomizes this neurobiological Kehre. Based on a symposium held this January in Paris, Jean-Pierre Changeux, Antonio Damasio, Wolf Singer, and Yves Christen have published a small book called Neurobiology of Human Values. This is really a remarkable title, since more than anything human values have been the foundation that the whole enterprise of a specific “human” science (Humanwissenschaft), in contrast to the natural sciences, have been built on. Human values, the argument runs, cannot be captured by natural laws (since they are changing and subjective), and therefore human behaviour cannot be the subject of the natural sciences but must be investigated by way of a particular “humanistic” methodology. As Changeux et al.’s book shows, this argument no longer holds up to scrutiny. The many experiments reported in the book’s papers demonstrate that it is, in fact, possible to unveil the neuronal processes underlying human values.

At the same time, the book is also important because its authors are almost all very senior and influential neuroscientists – besides the editors, there are chapters by, e.g., Frans de Waal, Richard Davidson, Nobel laureate Daniel Kahneman, Giacomo Rizzolatti, and Stanislas Dehaene. This will lend important credibility to the ongoing study of human values, a research topic which is yet not mainstream in the neuroscientific community. Thus, although it has its shortcomings (most of all, very sloppy copy-editing), Neurobiology of Human Values is a very welcome publication which deserve mentioning.

In coming days I will go through some of issues raised by the book, including aesthetic values, social values, ethical values, and economic values. And what exactly is a value, then? Stay tuned for the answer to that big question!

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