The purpose of the studies proposed here is to provide evidence for spatial influences on language function and to explore the anatomic and functional bases of these effects. In Part 1, subjects with single hemispheric infarctions will be tested on a battery of language tasks in which the location to which they attend will be systematically manipulated. Objectives of this component of the investigation are to determine the prevalence of spatial effects on language function and to define the anatomic bases of these effects by correlating performance with lesion site as defined by neuro-imaging studies. Those patients who demonstrate significant spatial effects on this test battery will serve as subjects in a second series of studies aimed at defining the mechanisms that underlie these effects. These studies, motivated by our provisional account of spatial effects on cognitive function (the spatial registration hypothesis), will examine the integrity of mechanisms involved in spatial representation and attention. In Part 2 we propose to examine spatial effects in normal language processing. In addition to providing converging evidence for spatial influences on language function and establishing the domain over which such influences apply, these studies will help to constrain interpretation of the data from studies of brain lesioned subjects in Part 1. The proposed investigations have both clinical and theoretical significance. From a theoretical standpoint, these studies should increase our understanding of the role of spatial information in maintaining distributed brain systems in registration, as well as of the brain mechanisms that support this binding function. The potential clinical significance of this work is also clear. If patients with brain injury do indeed demonstrate significant spatial effects in language processing, it may be possible to improve patients' functional capacity simply by controlling the site and/or side to which they attend or act.
