The human brain is not hard wired for reading; that is, unlike many other activities we do during a given day, there are no specific parts of the brain we can point to as being responsible for reading. As a species, we have not been alive long enough for evolution to have made reading part of our hardware. That we have been reading and writing for about 5,000 years is a mystery that can only be attributed to the brain's remarkable plasticity. It has reused other circuits of the brain to make reading happen. Neuroscientists have been a little vague about which circuits we have refashioned to fit our needs, but new research from neuroscientist Stanislas Dehaene has begun to unravel just what our brains are doing to read, and what we may have lost in the process.
Dehaene scanned the brains of 31 people who learned to read in childhood, 22 who learned in adulthood, and 10 who were illiterate. The individuals who COULD read showed greater activity to written words in parts of the brain that process what we see. Individuals who were illiterate showed little brain response to the visual image of words words. Dehaene previously argued that part of the brain where the left occipital and temporal lobes join is an important area for reading. In literate people, looking at words triggered brain activity in parts of the left temporal lobe that respond to what we see. In addition, Dehaene's research suggests that reading uses brain circuits that we already use for spoken language. Interestingly, researchers also found that in people who learned to read early in life, a smaller area of the left occipital-temporal cortex responded to images of faces than in the illiterate group. Is it possible that reduced recognition of faces is our payoff for the ability to read? Maybe, but we'll have to wait for Dehaene's results to find out.
Read a summary of Dehaene's research.
Tuesday November, 16, 2010 at 11:27AM