PROJECT SUMMARY/ABSTRACT The overall goal of this project is to elucidate the role neutrophils, both peripheral and meningeal, play in CNS homeostasis. Specifically, how neutrophil activity and location may influence the molecular landscape of neurons in learning and memory. During the mentored phase of this project, I will focus on characterizing the neutrophil population within the meninges, the location of these cells in the meninges, and determine whether the meninges act as a non-medullary source of neutrophils (Aim 1). During this period, I will also determine the specific role these cells play in modulating learning and memory in mice (Aim 2). The completion of these aims will help me develop skills in bioinformatics, establishing slice cultures and gain a rudimentary working knowledge of electrophysiological methods. These techniques will be of further use to me in the independent phase of this grant. During the independence phase, I will investigate elucidate the role of peripheral and meningeal neutrophils in different learning paradigms (Aim 2). Upon completion, this project will elucidate new neuromodulatory function of neutrophils and identify the meninges as a source of these cells within the CNS. These results will greatly inform our understanding of the role these cells play in injury and neurodegeneration.