PRISM ADAPTATION TO A RIGHTWARD OPTICAL DEVIATION REHABILITATES LEFT HEMISPATIAL NEGLECT

A large proportion of right-hemisphere stroke patients show hemispatia l neglect-a neurological deficit of perception, attention, representat ion, and/or performing actions within their left-sided space(1), induc ing many functional debilitating effects on everyday life, and respons ible for poor functional recovery and ability to benefit from treatmen t(2). The frequent parietal locus of the lesion producing neglect refl ects the impairment of coordinate transformation used by the nervous s ystem to represent extrapersonal space. Given that adaptation to a vis ual distortion can provide an efficient way to stimulate neural struct ures responsible for the transformation of sensorimotor coordinates, t he aim of our study was to investigate the effect of prism adaptation on various neglect symptoms, including the pathological shift of the s ubjective midline to the right. All patients exposed to the optical sh ift of the visual field to the right were improved on their manual bod y-midline demonstration and on classical neuropsychological tests. Unl ike other physiological manipulations used to improve neglect, this im provement lasted for at least two hours after prism removal and thus c ould be useful in rehabilitation programmes. The positive effect found for both sensorimotor and more cognitive spatial functions suggests t hat they share or depend on a common level of space representation lin ked to multisensory integration.