The principal aim of the proposed studies is to examine the role of the nonspecific thalamus in brain information processing. It is well-known that cognitive disturbances may arise from either structural or functional disturbances of the nonspecific thalamus as seen in several neurological disorders. To examine the cellular basis of these disturbances two primate models are proposed. In the propose studies visual processing is chosen as an assay to examine the role of the nonspecific thalamus in cortical information processing and visually guided behavior. In the first study, receptive fields of primary visual cortical neurons (Vl cells) will be studied before, during and after 3/s spike and wave complexes generated by stimulation of nonspecific thalamic structures (either intralaminar nuclei or median dorsalis). This experiment will exploit the advanced knowledge of V1 receptive field properties and the growing understanding the thalamocortical relationships. The second study proposes a primate model of thalamic neglect induced by reversible deactivation of the intraliminar nuclei. In this model behavior will be carefully studied with characterization of general behavior, oculomotor function and perceptual processing. The two projects form a comprehensive training in methods necessary for future independent investigation of the role of the nonspecific thalamus in cognitive disorders. The long-range goals of these studies to lay the foundation for eventual therapeutic intervention for cognitive dysfunction following stroke or head trauma.