30 March 2011

Reading in the Brain (Stanislas Dehaene)

The boyfriend's brother and sister-in-law got me Reading in the Brain for Christmas, theorizing that since they didn't know my favorite authors but knew I loved books, a meta-book would work. And they were so right, because this book was awesome.

Studies into the neuroscience of reading, says Dehaene, have identified a particular part of the brain that handles word forms: the "brain's letterbox," in the left occipito-temporal region; one of his central questions is how this is even possible...reading is too recent an invention for the human brain to have actually evolved the ability to do so, and yet the brains of readers the world over show that this "letterbox" is where written words are processed before being semantically understood. He hypothesizes a process called "neuronal recycling," in which the incredible plasticity of the primate brain repurposes "old" neurons for novel uses.

The real strength of this book is that it manages to be accessible without seeming at all dumbed down. Dehaene lays out the case for the brain's letterbox in exhaustive detail, starting with its discovery in the 19th century in the autopsy of a man who--after a stroke--lost the ability to read, though he could still write, still understand letters traced out on his hand, and even read out strings of digits: but letters were lost to him. This condition is called pure alexia, and it's beaten out alien hand syndrome on the list of incredibly rare malfunctions I am petrified of getting. Through ever more sophisticated imaging technology (PET, MRI, electrodes implanted in the brains of epileptics), neurologists have stacked up loads of evidence for the existence of this specialized brain area. There's repetition in this section, but that's science, you know? Confirming and reconfirming.

Dehaene also goes into the invention of writing and the development of alphabets, the process of learning to read and how it literally changes the brain, and what dyslexia can tell us about how reading works. It's all fascinating stuff: like how children often confuse letters with left-right symmetry (p & q, d & b) or mirror-write easily, because our brains are so used to generalizing from that kind of symmetry (that's why we can see a person in right profile and still recognize them in left profile, even if we haven't seen them from that angle before) that we actually have to unlearn this incredibly useful skill to understand the alphabet. It's a book that just makes you want to buttonhole people on the subway and share facts with them, and a great, great gift for anyone bookish in your life.

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