PROJECT SUMMARY The study will investigate how visual information is represented in the prefrontal cortex, the brain area involved with higher cognitive functions, before and after training to perform a working memory tasks. Monkeys will be trained in cognitive tasks that require them to observe and remember displays with multiple visual stimuli. Neurophysiological recordings with an array of microelectrodes as training progresses will allow us to determine the patterns of neuronal activation that determine the expected improvement in behavioral performance and working memory capacity. The experiments will uncover the nature of changes that take place in the prefrontal cortex during training to perform a working memory task.