Prism adaptation has been used for over a century to investigate sensory-motor
plasticity and control. Recently, adaptation to rightward-shifting prisms, resulting in a leftward orienting after-effect, has demonstrated promise for producing persisting and broadly generalised improvements in hemispatial neglect
('neglect'). Also, neglect-like patterns of performance have been reported in healthy participants after adaptation to leftward-shifting prisms. This thesis explores the higher-level cognitive effects of prism adaptation in healthy participants and neurological patients. There was no change in the symptoms of twelve patients with acute neglect following single sessions of prism adaptation (Chapter 2), suggesting that neglect chronicity may influence the potential for gaining benefit from the technique. In contrast, observations in patients with chronic lesions demonstrate, for the first time, that 1) right spatial neglect is reduced by adaptation to leftward-shifting prisms (Chapter 2); and 2) adaptation to rightward-shifting prisms reverses the local processing bias in patients with lesions to the right temporo-parietal junction (Chapter 4). Experiments in healthy participants demonstrate a neglect-like withdrawal bias (Chapter 3) and a reduced global processing bias (Chapter 5) after adaptation to leftward-shifting prisms. Therefore, a major outcome of this thesis is that the higher-level spatial influence of prism adaptation in both healthy and brain-lesioned participants is not limited to lateralised spatial attention, but also extends to non-lateralised fw1ctions. Finally, Chapter 6 describes prism adaptation treatment of
Complex Regional Pain Syndrome, an enigmatic disorder of neurogenically
maintained pain and distorted body representation. The results of this thesis suggest that perturbation of parietal lobe function by prism adaptation modifies lateralised and non-lateralised spatial deficits including spatial attention, hierarchical processing and body schema. These novel findings have implications for the rehabilitation of neglect and other disorders of right hemisphere dysfunction.