Visual-spatial selective attention is an essential brain function that enables human observers to select and process relevant information. The parietal lobes have long been implicated in this function. Although many studies have contributed significant information about the behavioral impairments in patients with parietal damage, little is known about the locus of information processing deficits in these patients. The experiments described in this proposal will investigate the role of the parietal lobes in the initial sensory processing of information as well as attentional modulation and orienting. To this end, patients with focal lesions will be tested in spatial attention paradigms. It is hypothesized that attentionaI deficits in these patients are manifest in part by impairments in the ability to attentionally modulate sensory information. Event-related potentials as well as response times will be recorded to index the precise processing stages during which these impairments occur.
