Left size distortion (hyperschematia) after right brain damage.
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
G
Université de Lyon, Université Lyon 1, Inserm UMR-S 534, Bron, France.
Michel
C
C
Rossetti
Y
Y
Boisson
D
D
Vallar
G
G
D001479:Basal Ganglia / Q000473:pathology / Q000503:physiopathology; D001921:Brain / Q000473:pathology / Q000503:physiopathology*; D001925:Brain Damage, Chronic / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D002540:Cerebral Cortex / Q000473:pathology / Q000503:physiopathology; D002544:Cerebral Infarction / Q000150:complications / Q000473:pathology / Q000503:physiopathology*; D003221:Confusion / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010468:Perceptual Disorders / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology; D013028:Space Perception / Q000502:physiology; D014057:Tomography, X-Ray Computed