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Cognitive & Behavioral Neurology:
doi: 10.1097/WNN.0b013e3181f22448
Original Studies

Interhemispheric Differences in Knowledge of Animals Among Patients With Semantic Dementia

Mendez, Mario F. MD, PhD*,†; Kremen, Sarah A. MD*; Tsai, Po-Heng MD*; Shapira, Jill S. RN, PhD*

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Objective: To investigate interhemispheric differences on naming and fluency tasks for living versus nonliving things among patients with semantic dementia (SD).

Background: In SD, left-temporal involvement impairs language and word comprehension, and right-temporal involvement impairs facial recognition. There may be other interhemispheric differences, particularly in the animate-inanimate dichotomy.

Method: On the basis of magnetic resonance imaging (MRI) ratings of anterior temporal atrophy, 36 patients who met criteria for SD were divided into 21 with left-predominant and 11 with right-predominant involvement (4 others were too symmetric for analysis). The left and right-predominant groups were compared on naming, fluency, and facial recognition tests.

Results: Consistent with greater language impairment, the left-predominant patients had worse naming, especially inanimate and letter fluency, than the right-predominant patients. In contrast, difference in scores suggested selective impairment of animal naming, animal name fluency, and semantic knowledge for animate items among the right-predominant patients. Proportionally more right than left-predominant patients misnamed animal items and faces.

Conclusions: These findings support interhemispheric differences in animal knowledge. Whereas left-predominant SD equally affects animate and inanimate words from language involvement, right-predominant SD, with greater sparing of language, continues to impair other semantic aspects of animals. The right anterior temporal region seems to make a unique contribution to knowledge of living things.

© 2010 Lippincott Williams & Wilkins, Inc.


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