The research supported by this application is concerned with localization of function in the human brain, and encompasses both basic and clinical research objectives. Basic research objectives include the anatomical localization and function characteristics of brain regions involve in the perception and recognition of faces, words, numbers, colors an motion. We also wish to determine the extent to which these brain regions are affected by, or participate in, attentive and memory processes. The major clinical research objective is the identification of critical cortical areas to be spared during removal of abnormal brain tissue. Three techniques will be used to achieve these goals; (1) Event-related potential recording from electrodes placed on the surface or within the brains of patients with epilepsy. This technique provides excellent temporal resolution of brain activity. (2) Cortical stimulation by means of electrode placed on the cortical surface. This technique provides an independent measure fee the importance and role of a stimulated region in the performance of sensory, cognitive and linguistic tasks. (3) Functional magnetic resonance imaging. This technique provides excellent spatial resolution of brain activity and can be carried out in normal subjects as well as neurosurgical patients. We will determine the degree to which the three methodologies yield the same answers with regard to localization of function. Intracranial recordings are carried out in collaboration with the Tale Epilepsy Surgery Program, while the imaging studies will be carried out in collaboration with the Tale Nuclear Magnetic Resonance Physics group.
Specific aims of the proposed studies are to determine the functional properties of the ventral visual pathway (which is important for object and word recognition), the dorsal visual pathway (which is important for the perception of motion and spatial relationships), the dorsal visual pathway (which is important for the perception of motion and spatial relationships), and the hippocampus (which is important for memory function). Several studies are designed to clarify early category-specific processing in the posterior ventral pathway (a region apparently insensitive to contextual and attentional effects), while other studies are designed to clarify late category-specific processing in the anterior ventral pathway (a region sensitive to the effects of priming, work type, and other semantic and contextual manipulations). Other studies will attempt to assess intermediate stages of ventral pathway processing, and to assess interactions of the dorsal and ventral pathways. A related specific aim is to develop better methods of functional imaging and analysis with the goal of minimizing artifact while maximizing the sensitivity of the technique. The proposed work will provide valuable information about how the brain perceives and remembers faces, words, and other important types of visual input, and will also provide clinical information important for preoperative neurosurgical planning.
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