Spatial Representation and Updating: Evidence from Neuropsychological Investigations

How spatial information is represented and updated over time and over changes in the position of the stimulus and/or observer is considered in the context of a population of patients who have impairment in spatial perception. We present data both from our own research with patients suffering from hernispatial neglect as well as from studies in the literature. Taken together, these studies suggest that spatial information is coded in more than one spatial frame of reference simultaneously and that the choice of reference frame depends on the demands of the tasks. Once the stimulus is located, however, the patients are able to update the position of the stimulus dynamically when walking or when undergoing passive rotation. The insights obtained from this neuropsychological population provides converging evidence for the psychological and neural mechanisms which mediate spatial representation and dovetail well with existing single unit recording and functional imaging data.