Pointing straight ahead: Reversed patterns of performance in right-brain-damaged patients with or without extensive parietal lesion

In order to study the effect of an extensive parietal lesion on the positio n of the egocentric reference in right-brain damaged patients, 33 unselecte d patients with right hemisphere focal lesions and 22 normal controls parti cipated in a straight-ahead pointing task. The results showed a significant effect of the presence of a right parietal lesion on pointing performance, with an ipsilesional deviation of the egocentric reference in patients suf fering from a lesion involving extensively the parietal lobe and a contrale sional deviation in patients with lesions that substantially spared the rig ht parietal lobe. These results can help explain some dissociations between left neglect signs and ipsilesional deviation of the egocentric reference, and raise some questions about the links among lesion location, neglect si gns and egocentric frame of reference. (C) 1999 Academic Press.