Your Brain on BookS

Stanislas Dehaene holds the chair of Experimental Cognitive Psychology at the Collège de France, and he is also the director of the INSERM-CEA Cognitive Neuroimaging Unit at NeuroSpin, France’s most advanced neuroimaging research center. He is best known for his research into the brain basis of numbers, popularized in his book, “The Number Sense.” In his new book, “Reading in the Brain,” he describes his quest to understand an astounding feat that most of us take for granted: translating marks on a page (or a screen) into language. He answered questions recently from Mind Matters editor Gareth Cook.

COOK: How did you become interested in the neuroscience of reading?
DEHAENE: One of my long-time interests concerns how the human brain is changed by education and culture. Learning to read seems to be one of the more important changes that we impose to our children's brain. The impact that it has on us is tantalizing. It raises very fundamental issues of how the brain and culture interact.
As I started to do experimental research in this domain, using the different tools at my disposal (from behavior to patients, fMRI, event-related potentials, and even intracranial electrodes), I was struck that we always found the same areas involved in the reading process. I began to wonder how it was even possible that our brain could adapt to reading, given it obviously never evolved for that purpose. The search for an answer resulted in this book. And, in the end, reading forces us to propose a very different view of the relationship between culture and the brain.

COOK: What is this “new relationship”?
DEHAENE: A classical, although often implicit, view in social science is that the human brain, unlike that of other animals, is a learning machine which can adapt to essentially any novel cultural task, however complex. We humans would be liberated from our past instincts and free to invent entirely new cultural forms.
What I am proposing is that the human brain is a much more constrained organ than we think, and that it places strong limits on the range of possible cultural forms. Essentially, the brain did not evolve for culture, but culture evolved to be learnable by the brain. Through its cultural inventions, humanity constantly searched for specific niches in the brain, wherever there is a space of plasticity that can be exploited to “recycle” a brain area and put it to a novel use. Reading, mathematics, tool use, music, religious systems -- all might be viewed as instances of cortical recycling.
Of course, this view of culture as a constrained “lego” game isn't that novel. It is deeply related to the structuralist view of anthropology, as exemplified by Claude Levi-Strauss and Dan Sperber. What I am proposing is that the universal structures that recur across cultures are, in fact, ultimately traceable to specific brain systems.
In the case of reading, the shapes of our writing systems have evolved towards a progressive simplification while remaining compatible with the visual coding scheme that is present in all primate brains. A fascinating discovery, made by the American researcher Marc Changizi, is that all of the world's writing systems use the same set of basic shapes, and that these shapes are already a part of the visual system in all primates, because they are also useful for coding natural visual scenes. The monkey brain already contains neurons that preferentially respond to an “alphabet” of shapes including T, L, Y. We merely “recycle” these shapes (and the corresponding part of cortex) and turn them into a cultural code for language.