This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
What do you think happens when you read these words?
(And did that thought blow your mind?)
Lobier et al. "The first 250ms in visual word recognition: who is talking to whom?" University of York, 509.18, XX35.
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So how does reading work? Right now, scientists think that when you read words on a page, the sight of the words first goes to the visual areas, then to higher order processing areas like the fusiform gyrus, and then to the language areas, including the inferior frontal gyrus. But some of this pathway doesn't line up. After all, if this all occurred sequentially, the inferior frontal gyrus would see activity last, right?
...it turns out it may see activity first. Or second, anyway.
The authors of this study noticed that the inferior frontal gyrus actually received information when reading awfully quickly, within 250 ms when confronted with a word. So the scientists wondered if this activity was being driven by the visual areas. How do you determine that? Will you take a bunch of brain scans, you do a lot of matching up in terms of time and activity...and you do a lot of math.
When they had people read individual words silently in a scanner and looked at the time at which the individual brain areas saw activity, the authors saw that the primary visual cortex and the inferior frontal gyrus are active at very similar points in time. As well as activating the frontal language areas in sequence with higher order sensory processing, the primary visual cortex can activate the inferior frontal gyrus directly.
And this has some interesting implications for how we process words as we read them. It suggests that reading is truly bottom up, not top down. You don't activate your language areas so you can read, instead the primary visual processing areas can directly activate higher language areas, and they do so very quickly, within 200 milliseconds. While this is cool just knowing HOW we read, it also could potentially help scientists understand what goes wrong in people with reading deficits, which might help them figure out how to help.