title: Blindsight in children with congenital and acquired cerebral lesions.
abstract: It has been shown that unconscious visual function can survive lesions to optical radiations and/or primary visual cortex (V1), a phenomenon termed "blindsight". Studies on animal models (cat and monkey) show that the age when the lesion occurs determines the extent of residual visual capacities. Much less is known about the functional and underlying neuronal repercussions of early cortical damage in humans. We measured sensitivity to several visual tasks in four children with congenital unilateral brain lesions that severely affected optic radiations, and in another group of three children with similar lesions, acquired in childhood. In two of the congenital patients, we measured blood oxygenation level dependent (BOLD) activity in response to stimulation of each visual field quadrants. Results show clear evidence of residual unconscious processing of position, orientation and motion of visual stimuli displayed in the scotoma of congenitally lesioned children, but not in the children with acquired lesions. The calcarine cortical BOLD responses were abnormally elicited by stimulation of the ipsilateral visual field and in the scotoma region, demonstrating a profound neuronal reorganization. In conclusion, our data suggest that congenital lesions can trigger massive reorganization of the visual system to alleviate functional effects of early brain insults.
authors.affiliation: Department of Psychology, University of Florence, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Tinelli
authors.forename: Guido Marco
authors.initials: GM
authors.lastname: Cicchini
authors.forename: Roberto
authors.initials: R
authors.lastname: Arrighi
authors.forename: Michela
authors.initials: M
authors.lastname: Tosetti
authors.forename: Giovanni
authors.initials: G
authors.lastname: Cioni
authors.forename: Maria Concetta
authors.initials: MC
authors.lastname: Morrone
mesh_terms: D000293:Adolescent; D001766:Blindness / Q000523:psychology*; D001927:Brain Diseases / Q000151:congenital / Q000523:psychology*; D002648:Child; D015350:Contrast Sensitivity; D005260:Female; D006423:Hemianopsia / Q000151:congenital / Q000523:psychology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D020244:Infarction, Middle Cerebral Artery / Q000151:congenital / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D009039:Motion Perception / Q000502:physiology; D009483:Neuropsychological Tests; D009949:Orientation / Q000502:physiology; D010100:Oxygen / Q000097:blood; D010775:Photic Stimulation; D013028:Space Perception / Q000502:physiology; D020521:Stroke / Q000151:congenital / Q000473:pathology; D016896:Treatment Outcome; D014785:Vision, Ocular / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology; D014795:Visual Pathways / Q000293:injuries / Q000473:pathology; D014796:Visual Perception / Q000502:physiology*
chemical_list: D010100:Oxygen