[On the hemispheric asymmetry of unilateral spatial neglect]

Many investigators were interested in unilateral spatial neglect (USN) and studied it in various respects. Especially the between-hemispheric difference of USN has been broadly argued. It can be considered as a well accepted fact that there is a difference of frequency of USN between left and right brain-damaged patients, however, there is no consistent opinion whether there are differences of severity and quality. To settle this dispute, 239 right-handed unilateral brain-damaged subjects were investigated on USN. 125 subjects suffered from left hemisphere lesions and 114 from right hemisphere lesions. Two tests; copy of drawings and finger imitation; were performed. On copying of drawings, each patient was required to copy line drawings of cubes, complex two-dimensional geometrical figures and simple two-dimensional geometrical figures. Those who failed to complete either the left- or right-hand side of any one of these drawings were classified as showing USN. Then failures of USN were divided into two different patterns; unilateral omission and unilateral distorsion. Again imitation of various finger patterns was tested with the hand homolateral to lesions. These items were presented by two methods. The subjects saw the dorsal side of the examiner's hand in the first, and palmar side in the second. On the copying of drawings, right brain-damaged subjects had about twice higher incidence of total USN than left brain-damaged subjects. As for omission alone, the incidence with the right hemispheric group was three times as high as the incidence with the left hemispheric group.(ABSTRACT TRUNCATED AT 250 WORDS)