Posterior Parietal Cortex Persistent Activity and Working Memory

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The number of things that humans can hold simultaneously in memory for a short time (our working memory) is remarkably small. The maximum is thought to be seven, as in the number of digits in a phone number, but the average is about only four! The limited capacity of our working memory depends on neural mechanisms that are distributed in the frontal and parietal lobes of our brain, but the current state of our knowledge is far from complete. On the one hand, only basic memory mechanisms have been studied because there exists no adequate animal model to study working memory capacity. On the other hand, nearly all our knowledge about these basic memory mechanisms has been obtained from studies of the frontal cortex despite all the evidence indicating that the parietal cortex also plays an important role. ******In the last tenure of this grant, we have established a new animal model to study working memory by adapting a simple procedure that has been extensively used in humans for that purpose. In this proposal, we will study the mostly unexplored neural substrate of working memory within the parietal cortex. While animals perform our novel working memory task, we will identify the neural signature of working memory from single neurons and small ensembles of neurons using microelectrodes and from large-scale populations of neurons using encephalography. In addition, we will determine the contribution of specific neurotransmitter receptors to working memory by testing the effects of drugs on performance in the behavioral task and on neural activity. ******The results of this research will have implications for the basic study of information processing taking place within and between neurons of the cerebral cortex, which can be applied to other brain functions, i.e., the limits of our perception and attention. In addition, it will allow students with diverse background - such as biology, psychology, engineering, computer and cognitive science - to gain high quality training in several experimental methods. This research experience will prepare them to enter various areas of research as emerging young leaders, thereby helping to satisfy the increasing demand for highly qualified individuals in academia and industries.**