Reviews: Rewiring the Brain

If old dogs haven’t been able to learn new tricks, maybe that’s because no one has known how to teach them properly. Until quite recently orthodox neuroscience held that only the brains of young children are resilient, malleable, and morphable—in a word, plastic.This neuroplasticity, as it is called, seems to fade steadily as the brain congeals into its fixed adult configuration. Infants can sustain massive brain damage, up to the loss of an entire cerebral hemisphere,and still develop into nearly normal adults; any adult who loses half the brain, by contrast, is a goner. Adults can’t learn to speak new languages without an accent, can’t take up piano in their fifties then go on to play Carnegie Hall, and often suffer strokes that lead to permanent paralysis or cognitive deficiencies. The mature brain, scientists concluded, can only decline.