Brain plasticity: Distinguishing "p"s from "q"s

A book review of “Reading in the Brain” (authored by French cognitive scientist Stanislas Dehaene) gives a very good illustration of our brains' partial plasticity:

[Dehaene] argues that the primate brain has evolved to treat symmetrical shapes, like the letter pairs p and q, or b and d, as if they were the same. This explains why children, and dyslexics, have so much trouble distinguishing these letters. It also explains our extraordinary ability to “mirror-read” and “mirror-write.” Many children spontaneously reverse not just single letters but whole paragraphs of text.

But if reading is so tightly constrained by innate brain structure, we’d expect that we would simply never use letters like b and d at all. Instead, Dehaene shows how the reading brain has developed a new ability to discriminate these symmetries, even at the neural level. A developing brain that is exposed to symmetrical letters with different meanings will rewire and overcome its natural symmetry-blindness.

I highly recommend to anyone interested in brain plasticity The Brain That Changes Itself, which shows how the longstanding neurological theory of “localization” and fixed brain structures has been overturned — or, at least, highly qualified — by fascinating research proving that our brains evolve and restructure themselves continually, in response to everything we do and see and hear.

Plasticity enables cultural evolution, which gives us real hope that we can make our world a better place, as the book review suggests:

We are born with a highly structured brain. But those brains are also transformed by our experiences, especially our early experiences. More than any other animal, we humans constantly reshape our environment. We also have an exceptionally long childhood and especially plastic young brains. Each new generation of children grows up in the new environment its parents have created, and each generation of brains becomes wired in a different way. The human mind can change radically in just a few generations.

Posted by James on Monday, January 04, 2010