Functional MRI of Congnitive Processes

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DESCRIPTION (provided by applicant): The overall goal of the research proposed in this application is to determine the brain activation patterns in the human frontal and parietal lobes during performance of specific spatial cognitive tasks, as revealed by high field strength (4 Tesla) functional magnetic resonance imaging (fMRI). Healthy women and men will be studied. The tasks are designed to test hypotheses of how some higher order spatial cognitive processes are represented in the frontoparietal cortex. The research proposed is centered on route-tracing. This function crucially depends on the integrity of this cortex, as evidenced by its disturbance following cortical damage, e.g. after stroke. The processes involved in route-tracing comprise tracing of route segments as well as turning from one segment to the next. We will test five hypotheses concerning the neural representation of these processes and their specific aspects for which parietal cortex might be instrumental. The first hypothesis is that the direction of tracing of a straight route segment is represented in an orderly fashion, such that there is an orderly map of the direction of tracing. The second hypothesis is that tracing of a complex route (i.e. a route composed of multiple segments) is a spatially distributed process that sequentially engages distinct parts of the frontoparietal cortex, as the process unfolds in time. The third hypothesis is that turning from one segment to the next involves a process of mental rotation between these two segments, such that the intensity of activation will depend on the angle of rotation. The fourth hypothesis is that this dependence of the activation on the angle of directional change will be qualitatively and quantitatively similar to the dependence observed in a stand-alone mental rotation paradigm. Finally, the fifth hypothesis concerns differences between women and men with respect to the brain activation patterns associated with tracing complex sequences and the dependence of activation on the turning angle and mental rotation. The potential achievement of these objectives is within reach, due to the adequate resolution afforded by the fMRI at high magnetic field, even for individual subjects. The data acquired will be analyzed using both traditional as well as specialized spatial statistical techniques. The results to be obtained are expected to provide novel insights into how the brain deals with dynamic, cognitive, visuomotor processes that are commonly disturbed in patients suffering from cortical damage, e.g. after stroke. In addition, they will provide an insight into possible hemispheric asymmetries and differences between women and men, especially with respect to the performance of sequential movement and mental rotation tasks