On the Rehabilitation of Hemispatial Neglect

This paper aims to show that hemispatial neglect can be rehabilitated by a treatment that manipulates spatial attention, and elucidates some issues relevant either to theories of hemispatial neglect or to theories of normal spatial attention. The first section deals with theories of neglect. In particular, the representational, arousal and attentional hypotheses are discussed. The attentional hypothesis is considered to be the one that accommodates all the features that characterise the deficit. The second section is devoted to discussing attentional-orienting in normals. The problems addressed are the distinction between covert and overt orienting, the distinction between voluntary and automatic orienting, the relation between attention orienting and eye movements, and whether there is a single mechanism or several modular mechanisms capable of orienting attention. The final section outlines the rationale and the results of our research on the rehabilitation of neglect. In this study spatial neglect was manipulated by the use of either overt or covert orienting but only voluntary attention was trained. Although the treatment was limited to the visual modality, extinction and neglect were tested in both visual and tactile modalities, before and after the treatment. The results showed a clear-cut improvement of visual neglect. Considering that the treatment was based exclusively on manipulating attention, this constitutes strong evidence in favour of the attentional hypothesis. Overt 152and covert orienting were equally effective in improving visual extinction and neglect. This result supports those hypotheses that assume a close relationship between eye movements and attention shifts. No improvement was observed for those tests that involved the tactile modality. This result shows that the mechanisms for shifting of attention in the visual and tactile modalities are largely independent. Therefore the modularity view of attention mechanisms was supported.