Egocentric and object-based visual neglect

Abstract

Abstract Patients with unilateral neglect characteristically fail to acknowledge or to respond appropriately to information towards their contralesional side, even though initial afferent pathways for such information can be demonstrably intact (see Chapters 2, 3, 7 and 23; Bisiach & Vallar 1988; Driver 1998; Robertson & Marshall 1993). Figure 4.1 provides an example of severe left visual neglect in a copying task. The association of such neglect with lesions centred on the right supramarginal gyrus, in the inferior parietal lobule (see Chapter 2, Fig. 2.1), provides one of the classic links between spatial cognition and the parietal lobe. However, it should be noted that while the area of lesion-overlap across most neglect patients certainly does fall within the right inferior parietal region, each individual case typically has quite extensive damage beyond this area as well, including white-matter. Thus, a rather diffuse network of areas will be impaired in most neglect patients. Correspondingly, recent neuropsychological studies suggest that neglect is a multi-component syndrome, with each neglect patient suffering from a number of problems in accordance with their own particular diffuse brain damage (e.g. Rafa! 1994; Thier & Karnath 1997; Mattingley et al. 1998).