Brain processes written words as unique ‘objects,’ GUMC neuroscientists say

Brain diagramWashington, DC – Neuroscientists at Georgetown University Medical Center have found that an area known to be important for reading in the left visual cortex contains neurons that are specialized to process written words as whole word units. Although some theories of reading as well as neuropsychological and experimental data have argued for the existence of a neural representation for whole written real words (an "orthographic lexicon"), evidence for this has been elusive.

"Reading relies on neural representations that are experience dependent," says senior author Maximilian Riesenhuber, PhD, of the GUMC Laboratory for Computational Cognitive Neuroscience. "Evolution did not provide each of us with a little dictionary in our heads."

Because the findings, published in the April 30 issue of Neuron, shed light on how written words are processed in the brain, they also provide clues as to how reading disorders such as dyslexia could arise, Riesenhuber says. "Previous studies have shown that this brain area is affected in reading disorders such as dyslexia, but it is unclear what the mechanisms involved are. Our data suggest that looking at the neuronal selectivity in this area might provide new insight. For instance, we would expect reading difficulties if neurons never become well tuned to words, making reading a slow, arduous process, just like it would be if reading all nonwords."

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