Brain’s Visual Dictionary Responds Differently to Words, Objects and Faces
Posted in News Release
WASHINGTON— Neuroscientists say new research confirms the presence of a specialized brain area that processes written words called the visual word form area (VWFA), and that the neurons in this so-called “visual dictionary,” are selective for words compared to faces or objects. The Georgetown University Medical Center (GUMC) scientists’ results also explain previous conflicting findings about the existence of the visual word form area.
Skilled readers can recognize words at lightning fast speed because they have been placed in their visual dictionary, say the GUMC neuroscientists. The visual dictionary idea rebuts the theory that the VWFA responds to many visual objects acting more as an integrator of visual and reading related language functions. The scientists explain that the conflicting findings about the VWFA are a result of the method used to identify it.
This VWFA finding, reported in the July 2 issue of the Journal of Neuroscience, is important because unraveling how the brain solves the complex task of reading can help in uncovering the neural basis of reading disorders such as dyslexia, say the scientists.
“Our study confirms that the VWFA responds selectively to written words,” says the study’s lead investigator, Laurie Glezer, PhD, a postdoctoral research fellow. She works in the Laboratory for Computational Cognitive Neuroscience at GUMC, led by Maximilian Riesenhuber, PhD, who is a co-author.
Glezer and her colleagues tested word recognition in 53 volunteers using fMRI. Participants viewed words, faces, and objects. When the researchers identified the VWFA in each subject, they observed that words activated the region significantly more than objects and faces, but that this word selectivity was washed out when the VWFA was defined based on the averaged brain activity. The scientists say this explains why other studies failed to find word selectivity in the VWFA.
“We show that there is quite a bit of variability in terms of the size and location of each person’s visual dictionary,” she says.
The authors report no personal financial interests related to the study. This study was funded by the National Science Foundation (1026934 and 0449743).
About Georgetown University Medical Center
Georgetown University Medical Center is an internationally recognized academic medical center with a three-part mission of research, teaching and patient care (through MedStar Health). GUMC’s mission is carried out with a strong emphasis on public service and a dedication to the Catholic, Jesuit principle of cura personalis — or “care of the whole person.” The Medical Center includes the School of Medicine and the School of Nursing & Health Studies, both nationally ranked; Georgetown Lombardi Comprehensive Cancer Center, designated as a comprehensive cancer center by the National Cancer Institute; and the Biomedical Graduate Research Organization (BGRO), which accounts for the majority of externally funded research at GUMC including a Clinical and Translational Science Award from the National Institutes of Health.