Unilateral Spatial Neglect
Abstract
Unilateral spatial neglect is a neuropsychological syndrome, more frequent after damage to the right cerebral hemisphere, featuring an impaired ability to orient toward the contralateral left side of space and the body, and the inability to detect and report events from that side, of which patients are not aware. In addition to these defective manifestations, patients may show gratuitous behaviors, which include additional productions, unrelated to the task’s demand, such as drawings and repeated marks (perseveration) in exploratory target cancellation tasks. Neglect is a multi-component deficit, whose diverse manifestations share a divide between the attended ipsilateral and the neglected contralateral sides of space. Different pathological mechanisms contribute to neglect, including perceptual and premotor impairments, that may be specific to sensory modality, sector of space, and mental images. Neglect may manifest in different coordinate frames with reference to the body and body parts, and objects (egocentric and allocentric neglect). Spatial neglect is a severely disabling disorder, which interferes with functional recovery from stroke. The neural correlates of neglect include cerebral cortical regions surrounding the sylvian fissure. The posterior inferior-parietal cortex, the temporo-parietal junction, the posterior-superior temporal and the frontal premotor cortices, subcortical gray nuclei and white matter fiber tracts connecting these regions. Neglect is independent of, and cannot be traced back to, sensory and motor deficits, and may be interpreted as a derangement of multiple networks, primarily based in the right hemisphere, supporting spatial attention and representation of space and objects in it.
