Spatial neglect: a new technique for examining the neural correlates of visual processes involved in neglect

Spatial neglect is a complex neurological syndrome in which patients appear to experience a variety of attentional deficits across sensory modalities. The syndrome does not involve impairment in sensory processing, nor in cortical processes involved in the primary sensory cortices (primary visual cortex, primary auditory cortex, and so on). Instead, the syndrome manifests following damage to a range of cortical regions centred around the lateral parietooccipital border in the right cortical hemisphere. The lateral parieto-occipital border contains a number of visual cortical processing areas, and visual inattention is a dominant feature of many patients neglect. Using the "tuning properties" of visual cortical cells in that area we have developed a tool that can be used to explore the nature of visual processes occurring in the neglected hemi-field, that will probe the level of processing at which those deficits first arise, and which can be used to examine a new treatment for neglect - prism adaptation. Our data illustrate the sensitivity of the tool and show that the stimuli used for testing do examine the cortical locus affected by prism adaptation.