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Neglect behavior of experimental animals with unilateral posterior cortical lesions improves with the placement of a second lesion in the contralesional superior colliculus or in the intercollicular commissure. Given that the retinotectal fibers are mainly crossed, it has been speculated that ipsilesional eye patching, by depriving the contralesional superior colliculus of its main facilitatory visual input, might achieve similar results, and thus be used as a remediation maneuver in patients with neglect. From six patients with severe persistent neglect, only one showed an unequivocal beneficial effect from ipsilesional eye patching. We discuss the factors which possibly underlie success and failure with this procedure, and the place for it in neglect rehabilitation.

Experimental animals with large posterior-cortical lesions develop disturbances of visual perception and visually-guided behavior in the contralateral space, resembling the syndrome of unilateral spatial neglect (USN) in humans. The visuo-motor performance in the ignored space is recovered some time following additional lesion inflicted to the contralesional superior colliculus or section of the intercollicular pathways. Based on the model that explains this recovery by disinhibition of the ipsilesional superior colliculus (the ‘Sprague effect’) Posner and Rafal [37] proposed that ipsilesional monocular occlusion could possibly reduce the ‘tone’ of contralesional collicular neurons thereby removing an important contributor of hemineglect. A group of twenty-six right-hemisphere-damaged patients with USN was given a cancellation task under binocular and monocular (left and right) viewing conditions. Thirteen patients showed amelioration of left hemineglect in conditions of left-monocular viewing, as compared to the baseline binocular state. Although this result superficially resembles the Sprague effect, two patients benefited from right-monocular viewing whereas eleven patients showed no significant change in either right or left viewing conditions. The possible role of structures mediating interocular differences in target detection in cases of right hemisphere damage is discussed. It is suggested that even if the Sprague effect contributes to the salubrious influence of monocular viewing it is hardly the single factor involved.

Experimental animals with large posterior-cortical lesions develop disturbances of visual perception and visually-guided behavior in the contralateral space, resembling the syndrome of unilateral spatial neglect (USN) in humans. The visuo-motor performance in the ignored space is recovered some time following additional lesion inflicted to the contralesional superior colliculus (SC) or section of the intercollicular pathways. Based on the model that explains this recovery by disinhibition of the ipsilesional SC (the ‘Sprague effect’) Posner and Rafal [37] proposed that ipsilesional monocular occlusion could possibly reduce the ‘tone’ of contralesional collicular neurons thereby removing an important contributor of hemineglect. A group of twenty-six right-hemisphere-damaged patients with USN was given a cancellation task under binocular and monocular (left and right) viewing conditions. Thirteen patients showed amelioration of left hemineglect in conditions of left-monocular viewing, as compared to the baseline binocular state. Although this result superficially resembles the Sprague effect, two patients benefited from right-monocular viewing whereas eleven patients showed no significant change in either right or left viewing conditions. The possible role of structures mediating interocular differences in target detection in cases of right hemisphere damage is discussed. It is suggested that even if the Sprague effect contributes to the salubrious influence of monocular viewing it is hardly the single factor involved.

Voeller and Heilman (1988a) have produced evidence suggesting a right-hemisphere dysfunction associated with attention-deficit hyperactivity disorder (ADHD): ADHD-related hemineglect. The present study is a constructive replication, using carefully screened children with ADHD for a number of compromising factors (e.g., no lateralized brain damage, handedness, eyedness). Each child received two tests: Line Bisection and Visual Target Cancellation Test. In addition, their performance was assessed in both binocular and monocular viewing conditions. While the ADHD children performed generally worse than the controls on target cancellation (i.e., exhibiting higher inattention), there was no evidence for hemineglect. To complicate matters, a reversed right-left imbalance was tapped using a structured task array for this test, for left-eye dominant ADHD children not on medication. Besides drawing attention to the role of the dominant eye in the scanning of children with ADHD, we suggest that no firm conclusions regarding an ostensible ADHD-related hemineglect may be drawn.

Summary The parieto-occipital (PO) index of the VEP alpha-afterdischarge (AD) was assessed bilaterally in normal subjects in three successive sessions separated by one-three weeks with two within-session retests. Correlations between PO values and asymmetries of occipital and parietal width, mastoid area, basal angle, cephalic, and plagiocephaly indices were established in simple correlation and stepwise multiple regression analysis. Occipital width, notably in the right hemisphere correlated reliably with the PO index in relaxed wakefulness and the vigilance task. The population having normal and reversed occipital brain width is predicted to have different parieto-occipital AD distribution. Some errors of lateral EEG measurements introduced by slant cranial deformity are discussed in order to call attention to the fact that anatomy-related lateral EEG changes may masquerade as cognition-related asymmetries.

Neglect behavior of experimental animals with unilateral posterior cortical lesions improves with the placement of a second lesion in the contralesional superior colliculus or in the intercollicular commissure. Given that the retinotectal fibers are mainly crossed, it has been speculated that ipsilesional eye patching, by depriving the contralesional superior colliculus of its main facilitatory visual input, might achieve similar results, and thus be used as a remediation maneuver in patients with neglect. From six patients with severe persistent neglect, only one showed an unequivocal beneficial effect from ipsilesional eye patching. We discuss the factors which possibly underlie success and failure with this procedure, and the place for it in neglect rehabilitation.