Simulating unilateral neglect in normals using prism adaptation: implications for theory

• Published in: Neuropsychologia Vol. 41; no. 1; pp. 25 - 39
• Main Authors: Michel, Carine, Pisella, Laure, Halligan, Peter W, Luauté, Jacques, Rode, Gilles, Boisson, Dominique, Rossetti, Yves
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.01.2003; Elsevier Science; Elsevier
• Subjects: Adaptation, Physiological; Adolescent; Adult; Analysis of Variance; Anatomical correlates of behavior; Behavioral psychophysiology; Biological and medical sciences; Bisection; Female; Functional Laterality - physiology; Fundamental and applied biological sciences. Psychology; Humans; Lenses; Life Sciences; Male; Middle Aged; Neurons and Cognition; Neuropsychological Tests; Perceptual Disorders - diagnosis; Perceptual Disorders - physiopathology; Perceptual Disorders - rehabilitation; Photic Stimulation; Plasticity; Prism adaptation; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Psychomotor Performance - physiology; Space Perception - physiology; Space representation; Spatial neglect; Vision, Ocular - physiology; Visual Fields; Visuomotor; Prism adaptation; Visuomotor; Bisection; Space representation; Spatial neglect; Plasticity; Human; Perceptual adaptation; Healthy subject; Cognition; Experimental study; Sensorimotor coordination; Prism; Spatial representation; Bisection task
• DOI: 10.1016/S0028-3932(02)00135-5
• ISSN: 0028-3932

Rightward deviation on line bisection is considered one of the most classic clinical signs of unilateral visual neglect—a cognitive disorder of spatial processing that commonly follows right brain damage. Recently, short-term adaptation to wedge prisms has been shown to significantly reduce neglect on this and other conventional diagnostic tasks. Our previous study has shown that visuomotor adaptation in normals produces a similar pattern of directional bias on a line bisection task. Based on the good working knowledge of how neglect patients perform on different versions of the standard diagnostic task, we showed here that using leftward-deviating prisms in normals, it is possible to produce: (1) a reliable bias on line bisection, (2) a rightward specific deviation, (3) a modulation of rightward deviation, which depends on the relative spatial location of the target lines and (4) a line length effect. A final experiment confirmed that these after-effects are specific to prism adaptation rather than passive prism exposure. Collectively, these findings confirm that adaptation to left-deviating prisms in normals produces a reliable right-sided bias and as shown by a previous visuospatial judgement task, these findings cannot be adequately explained by the symmetric sensori–motor effects of prism adaptation. Taken together with the improvement of spatial neglect shown by right-deviating prisms only, the present study suggests that low level sensori–motor adaptations play a greater role in right hemisphere organisation for spatial cognition than previously thought.