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New Study Reveals Neural Basis for Tip-of-the-Tongue Experiences

You’ve known the person for years but you just can’t think of their name. You know it’s not Mark but sounds something like that. It’s just on the tip of your tongue…

Tip-of-the-tongue (TOTs) experiences are a common language phenomena which dramatically interrupt normally effortless speech. They cause significant discomfort and frustration at any age, but TOTs increase with age, and older adults report TOTs as their most frequent and troubling cognitive problem.

Prof. Deborah Burke’s newest research, published in the December issue of the Journal of Cognitive Neuroscience, identifies for the first-time a neural basis for word-finding failures, those situations where people are temporarily unable to produce a word they are certain they know.

The research project involved magnetic resonance images (MRI) of healthy participants between 19 and 88 years old and used voxel-based morphometry (VBM) to measure grey matter density throughout the brain. In a separate session, participants named celebrities cued by pictures and descriptions, indicating when they had a TOT, and completed the Raven’s Progressive Matrices, a non-verbal test of cognitive ability.

The number of TOTs increased with age and also with grey matter atrophy in the left insula, an area implicated in phonological production. The relation between TOTs and left insula atrophy could not be attributed to the correlation of each variable with age because TOTs were related to insula atrophy even with age effects removed. Moreover, errors on the RPM increased with age, but performance did not correlate with grey matter density in the insula.

“Because there is considerable brain atrophy with age,” explains Burke, “our finding that the number of TOTs is related to the amount of insula atrophy has the greatest significance for older adults and their age-related increases in TOTs. However, TOTs are related to the size of the insula even in younger adults, it's just that the variation in the insula here is smaller, and so is the variation in number of TOTs.

THE GOOD NEWS
“While age-related atrophy in the brain is currently irreversible,” says Burke, “the good news is that you can have atrophy in one area of the brain but other areas can pick up those functions.”

“The best way to strengthen those connections is to exercise your language skills, use language and use words,” says Burke. “I urge older adults to do things like read aloud, talk to people at dinner and play games like Scrabble which exercise their language skills. Playing games like bingo, poker or bridge, require little language and thus would probably not aid in word finding, though if you analyze your game with other players and socialize before and after playing, it should strengthen word production.

THE EXPERT
Burke, the W.M. Keck Professor of Distinguished Service and a professor of psychology and linguistics and cognitive science at Pomona College, is a five-time winner of the Pomona College Wig Distinguished Professor Award for Excellence in Teaching. She has received research support for her work on memory and language from the National Institutes of Health since 1989 and has discussed her research with a variety of media outlets over the years, including BBC Radio and National Public Radio.

The article, “On the tip-of-the-tongue: Neural correlates of increased word-finding failures in normal aging,” was co-authored with Meredith Shafto ’96 and Phyllis P. Tam ’04 (both from Pomona College and Cambridge University), and Emmanuel A. Stamatakis and Lorraine Tyler (from Cambridge).

JOURNAL OF COGNITIVE SCIENCE WEBSITE:
http://jocn.mitpress.org