We have known for decades that older adults' memory function declines with age. In the past 15 years, we have learned much about what causes these declines by studying behavioral changes in speed of processing, working memory, and inhibitory function. In the past 15 years, we have learned much about what causes these declines by studying behavior changes in speed of processing, working memory, and inhibitory function. In the past five years, much of the focus on understanding the causes of age-related decline in memory function have shifted to understanding the brain mechanisms associated with age-related cognitive decline,, through the use of functional neuroimaging techniques. The results from this small body of literature have been startling. We now have some evidence to suggest that as we age, neural reorganization occurs so that older adults use more or different brain structures compared to young to perform the same tasks. Thus, older brains may not simply function more slowly or less efficiently, they may function differently from young brains in fundamental ways. There is simply not enough data to known. The use of event-related functional neuroimaging (fMRI) allows us to examine how old brains may work differently from young brains, while processing the same information. The focus of this proposal then is on understanding the neural circuitry associated with encoding and retrieval processes across the lifespan. We restrict our work to the study of picture memory and imagery formation, generation, and manipulation. This task domain is an excellent one to study because it involves the activation of many important brain sties (dorsolateral prefrontal, mediotemporal, and occipital cortices). Moreover, long-term memory for pictures is a task where we have demonstrated in our lab reliably that old and young demonstrate similar performance at the behavioral level. Thus, we can use picture memory tasks to understand whether differences in neural circuitry exist between young and old when they behaviorally evidence the same level of performance on a memory task. We also propose to understand neural activations on image generation and manipulation tasks, tasks where older adults perform more poorly. We also include middle-aged adults in out samples, adopting a true lifespan approach, so that we can understand where in the life-course transitions to different brain activation patterns occur. The experiments we have designed permit us to determine, as well, neural activation associated with remembered and forgotten items in young and old adults and both encoding and retrieval. This will help us understand where there are particular difficulties in memory-at the time the material is studied, at the time it is retrieved, or both. The present studies should greatly enhance our understanding of how behavioral function on cognitive tasks relates to brain organizations across the lifespan.
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