Severity of neglect predicts accuracy of imitation in patients with right hemisphere lesions

Goldenberg [Goldenberg, G. (1996). Defective imitation of gestures in patients with damage in the left or right hemisphere. Journal of Neurology, Neurosurgery, and Psychiatry, 61, 176-180] proposed that the vulnerability of the imitation of meaningless gestures to right or left brain damage depends on the body parts that are involved in the gestures. Whereas imitation of hand postures was disturbed only in patients with left brain damage, imitation of finger postures was affected to similar degrees in left and right brain damage. Subsequent studies confirmed the selective vulnerability of hand postures to LBD but failed to replicate the severe disturbance of finger postures in RBD. In contrast to Goldenberg's studies, these studies excluded RBD patients with neglect. The present investigation aimed to explore the relationship between spatial neglect and imitation of finger postures in RBD patients. Presence and severity of spatial neglect and accuracy of imitation of hand and finger postures were tested in 50 RBD patients. Disturbance of imitation was much more severe for finger than hand postures and was tightly correlated with severity of neglect. The number of errors was higher for fingers which from the patient's perspective were located on the left side of the examiner's demonstrating hand but this spatial bias was not sufficient to explain all errors. Possible causes for non-lateralized errors could be a general narrowing of the focus of attention and reduced capacity for processing of visual information which have been postulated to be regular companions of the lateral displacement of attention in spatial neglect.