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September 2002

Manual Approach During Hand Gesture Imitation

Author Affiliations

From the Departments of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea (Drs Kwon and Na, Mss Kang, Lee, and Chin), and the University of Florida and the Veterans Affairs Medical Center, Gainesville (Dr Heilman). Dr Kwon is now affiliated with the Department of Neurology, Changwon Fatima Hospital, Changwon, Korea.

Arch Neurol. 2002;59(9):1468-1475. doi:10.1001/archneur.59.9.1468

Background  Patients' tendency to draw near or into the target when copying figures, a phenomenon termed closing-in, has been previously described. That the closing-in could occur when copying hand gestures has also been noted.

Objectives  To study a patient with corticobasal degeneration to quantify his manual approach behavior and to test a possible working memory hypothesis.

Methods  The subject of this study is a patient with severe ideomotor apraxia from probable corticobasal degeneration. Fluorine 18–labeled deoxyglucose–positron emission tomographic findings revealed a hypometabolism involving the bilateral parietotemporal and the right frontal lobes. When asked to copy an examiner's (J.C.K.) hand gesture, the patient approached, touched, or grasped the examiner's hand, a behavior mostly consistent with the closing-in behavior previously proposed. To investigate the frequency and severity of closing-in, the patient was asked to copy 20 meaningless hand gestures (10 simple and 10 complex). Copying the 20 hand gestures was performed with either the left or the right hand while the patient was seated opposite the examiner (across condition) or on the same side of the examiner (lateral condition).

Results  Of the 80 trials, closing-in occurred in 43 (53.8%) (35 with approaching, 6 with touching, and 2 with grasping). The closing-in was more frequent and more severe when gesturing with the left than the right hand, but it did not differ between the lateral and across conditions and between simple and complex gestures.

Conclusions  Corticobasal degeneration might be associated with aberrant manual approach behavior. Although our results do not support the working memory hypothesis, frontal dysfunction might have led to a loss of voluntary control of ontologically primitive propensity to move the forelimb in the direction to which one attends.