Objective: To quantitate a size distortion involving the side of space contralateral to the lesion (contralesional) in two right-brain-damaged patients. Methods: We studied two right-brain-damaged patients with lesions sparing the occipital lobe and a mild left neglect on target cancellation or line bisection. The lesions involved the temporoparietal region ( Patient 1) and the basal ganglia and the insula (Patients 1 and 2). Patients were given drawing tasks and tasks requiring perceptual and visuomotor judgments of horizontal extent. Results: In drawing objects such as a daisy both from memory and by copying, patients exhibited a disproportionate enlargement of the left-hand side of objects and added more left-sided petals to the drawn daisy. This pathologic behavior persisted when the patients were blindfolded and was likely to reflect a perceptual, rather than premotor, size distortion. In a task requiring the perceptual matching of two rectangles, patients underestimated the left-sided stimulus. In a visuomotor task requiring the reproduction of the horizontal extent of a segment, patients exhibited a hyperextension, when a leftward movement was required. Conclusions: We showed a disordered representation of extrapersonal space, possibly involving a contralesional relaxation of the spatial medium. The deficit does not arise at the level of retinotopic coordinate frames and is independent of unilateral spatial neglect.
Rode, G., Michel, C., Rossetti, Y., Boisson, D., Vallar, G. (2006). Left size distortion (hyperschematia) after right brain damage. NEUROLOGY, 67(10), 1801-1808 [10.1212/01.wnl.0000244432.91915.d0].
Left size distortion (hyperschematia) after right brain damage
Vallar, G
Membro del Collaboration Group
2006
Abstract
Objective: To quantitate a size distortion involving the side of space contralateral to the lesion (contralesional) in two right-brain-damaged patients. Methods: We studied two right-brain-damaged patients with lesions sparing the occipital lobe and a mild left neglect on target cancellation or line bisection. The lesions involved the temporoparietal region ( Patient 1) and the basal ganglia and the insula (Patients 1 and 2). Patients were given drawing tasks and tasks requiring perceptual and visuomotor judgments of horizontal extent. Results: In drawing objects such as a daisy both from memory and by copying, patients exhibited a disproportionate enlargement of the left-hand side of objects and added more left-sided petals to the drawn daisy. This pathologic behavior persisted when the patients were blindfolded and was likely to reflect a perceptual, rather than premotor, size distortion. In a task requiring the perceptual matching of two rectangles, patients underestimated the left-sided stimulus. In a visuomotor task requiring the reproduction of the horizontal extent of a segment, patients exhibited a hyperextension, when a leftward movement was required. Conclusions: We showed a disordered representation of extrapersonal space, possibly involving a contralesional relaxation of the spatial medium. The deficit does not arise at the level of retinotopic coordinate frames and is independent of unilateral spatial neglect.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.