Anterior-posterior interhemispheric differences in the loci of lesions producing visual hemineglect

Five neuropsychological tests designed to measure the presence and severity of visual hemineglect were given to 101 patients with clearly defined unilateral lesions. Of these, visual hemineglect was present in 28 out of a total of 56 left brain damaged (LBD) patients and in 20 out of 45 right brain damaged (RBD) patients. The incidence of hemineglect in these groups did not differ significantly, but the severity of hemineglect was greater in the RBD group than in the LBD group. However, the two groups were found to differ significantly with respect to the loci of the lesions most likely to result in hemineglect. In the RBD group most patients with hemineglect had posterior lesions, and in the LBD group most patients with hemineglect had anterior lesions. Possible reasons for this were discussed first from the point of view of an inattention hypothesis and second in terms of the effects the lateralization of language representation might have on the representation of spatial functions.